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Bioaccumulation of lipophilic substances in fish early life stages
Abstract
Accumulation of 14C-labeled polycyclic aromatic hydrocarbons, naphthalene, phenanthrene, pyrene, and benzo(a)pyrene and polychlorinated biphenyl (PCB) congeners PCB 31 and PCB 105 with a log octanol/water partition coefficient (Kow) range from 3.37 to 6.5 was investigated in eggs and larvae of zebra fish (Brachydanio rerio), and in larvae of cod (Gadus morhua), herring (Clupea harengus), and turbot (Scophthalmus maximus). Significant differences in the uptake and elimination rate constants between eggs and larvae of zebra fish were seen. The low rate of uptake and the lower elimination rate of eggs did, however, lead to bioconcentration factors (BCFs) comparable to those for larvae. As biotransformation of xenobiotics in embryonic and larval stages was indicated to be insignificant compared to juvenile/adult stages, body burdens of readily biotransformed chemicals may be higher in fish early life stages. Because weight and lipid content did not differ much between the investigated species, the main reason for the variability in BCFs between marine species (cold water species) and freshwater species (warm water species) was considered to be caused by differences in exposure temperatures that affect the degree of biotransformation. Due to the smaller size of larvae and thus an increased total surface of the membranes per unit fish weight, steady-state conditions were reached at a faster rate in early life stages than in juvenile/adult life stages. The lipid-normalized bioconcentration factors (BCFL) were linearly related to Kow, but BCFL was, in general, higher than Kow, indicating that octanol is not a suitable surrogate for fish lipids. Differences in bioconcentration kinetics between larvae and juvenile/adult life stages are considered to be the main reason for the higher sensitivity, with respect to external effect concentrations, generally obtained for early life stages of fish.
... In addition, previous studies suggest that the accumulation of lipophilic contaminants can also occur more rapidly at higher temperatures (Sprague 1969;Korn et al. 1979;Petersen and Kristensen 1998), likely due to a combination of increased solubility of contaminants in the water column and increased rate of organismal uptake. The established concept describing the relationship between temperature and toxicity used in biological effects modelling, states that with each increase of 10°C in the environment, organisms are expected to exhibit a 2-4 fold increase in reaction rates (Q10 concept; Lydy et al 1999). ...
... Relationship between elimination and hydrophobicity of PACs -Previous studies have used a regression of ε values and K OW to describe the relationship between elimination rate (ε) and the hydrophobicity of different narcotic chemicals (Spacie and Hamelink 1982;Petersen and Accepted Article Kristensen 1998;Baussant et al. 2001;French-McCay 2002). The relationship was determined using the following equation: ...
... Relationship between elimination and hydrophobicity of PACs -Previous studies have used a regression of ε values and K OW to describe the relationship between elimination rate (ε) and the hydrophobicity of different narcotic chemicals (Spacie and Hamelink 1982;Petersen and Accepted Article Kristensen 1998;Baussant et al. 2001;French-McCay 2002). The relationship was determined using the following equation: ...
Polycyclic aromatic compounds (PACs) present in the water column are considered to be one of the primary contaminant groups contributing to the toxicity of a crude oil spill. Because crude oil is a complex mixture composed of thousands of different compounds, oil spill models rely on quantitative structure activity relationships (QSARs) like the target lipid model (TLM) to predict the effects of crude oil exposure on aquatic life. These models rely on input provided by single species toxicity studies which remain insufficient. Though the toxicity of select PACs have been well studied, there is little data available for many, including transformation products like oxidized hydrocarbons. In addition, the effect of environmental influencing factors like temperature, on PAC toxicity is a wide data gap. In response to these needs, in the present study, stage I lobster larvae were exposed to 6 different understudied PACs (naphthalene, fluorenone, methylnaphthalene, phenanthrene, dibenzothiophene, and fluoranthene) at 3 different relevant temperatures (10, 15 and 20°C) all within the biological norms for the species during summer when larval releases occur. Lobster larvae were assessed for immobilization as a sublethal effect and mortality following 3, 6, 12, 24, and 48 h of exposure. Higher temperatures increased the rate at which immobilization and morality was observed for each of the compounds tested and also altered the predicted critical target lipid body burden (CTLBB), incipient LC50 , and elimination rate. Our results demonstrate that temperature has an important influence on PAC toxicity for this species and we provide critical data for oil spill modeling. More studies are needed so oil spill models can be appropriately calibrated and improve their predictive ability.
... The embryonic and larval period of polar cod is long and the surface area to volume ratio is high compared to adults (Miller and Kendall, 2009), increasing the time and area available to come in contact with a potential oil spill. Generally, fish ELSs are more sensitive to toxicants Petersen and Kristensen 1998), attributed to the relatively underdeveloped organs, lower metabolism during early ontogeny, and altered toxicokinetics compared to adults (Jung et al., 2015;Ingvarsdottir et al., 2012;Petersen and Kristensen ,1998;Paine et al., 1992). Increased bioaccumulation of lipophilic compounds during the prolonged embryo stage, in concert with developmental stage-specific biotransformation rates and high lipid concentrations may elevate the body burden, the internal concentration of the compound(s), of exposed ELSs . ...
... The embryonic and larval period of polar cod is long and the surface area to volume ratio is high compared to adults (Miller and Kendall, 2009), increasing the time and area available to come in contact with a potential oil spill. Generally, fish ELSs are more sensitive to toxicants Petersen and Kristensen 1998), attributed to the relatively underdeveloped organs, lower metabolism during early ontogeny, and altered toxicokinetics compared to adults (Jung et al., 2015;Ingvarsdottir et al., 2012;Petersen and Kristensen ,1998;Paine et al., 1992). Increased bioaccumulation of lipophilic compounds during the prolonged embryo stage, in concert with developmental stage-specific biotransformation rates and high lipid concentrations may elevate the body burden, the internal concentration of the compound(s), of exposed ELSs . ...
Environmental change in the Arctic is occurring at an unprecedented rate with a loss of sea ice and warmer sea temperatures, simultaneously as increased human activity in the Arctic poses a risk of petroleum pollution. The potential future of a key Arctic forage fish, polar cod (Boreogadus saida), was investigated using laboratory simulations of oil spills during sensitive life-history stages: maturation, post-spawning, and early life stages. I hypothesized that exposure to crude oil would result in adverse effects on individual fitness during these sensitive life-history stages. Changes in growth, metabolism, reproduction, and survival were followed to provide an integrated response to determine the risk to individual fitness to deliver more robust predictions for effects at the population and ecological levels. Findings reveal the physiological robustness of mature stages of polar cod chronically exposed to low levels (post-spill concentrations) or acutely to high (present-spill) crude oil concentrations. Effects observed on sperm motility under dietary exposure and gonadal development in females exposed to burned oil residues, an oil spill response action, require follow-up examination, especially in light of the importance of gamete quality to individual fitness. Reduced energy reserves and condition in the post-spawning stage suggests increased physiological sensitivity of this life-history stage. The high sensitivity of eggs and larvae to low levels of crude oil was further amplified by a 2.3°C increase in water temperature. The interactive effects of warmer water and low levels of petroleum pollution demonstrate the vulnerability of polar cod early life stages. Determining how the sentinel species, polar cod, will respond to these environmental and ecological stressors and what influence this will have on the resilience of the Arctic marine ecosystem is the future aim of this research.
... Atlantic cod (Gadus morhua) is a fish species of substantial economic importance, and therefore there is considerable interest in the effects of environmental factors and stressors (such as temperature and xenobiotics) on its life history. The early-life stages of fish are crucial for recruitment of both natural and cultured fish stocks (Kamler, 2008), and are regularly specifically sensitive to chemical stress (see e.g., Petersen and Kristensen, 1998;Massei et al., 2015). Interpreting, understanding and ultimately predicting stressor effects on the life history requires bioenergetic models (Jager et al., 2013). ...
... To apply the model to toxicants, it needs to be extended with a toxicokinetics module; for eggs and yolk-feeding larval stages, this requires special consideration. For example, the rate of chemical exchange for the egg stage is considerably slower than for the larvae post hatching (Petersen and Kristensen, 1998), and yolk and structure may differ in their affinity for chemicals (see Jager, 2016). Furthermore, there may also be stage-specific mechanisms of toxicity in the early life stages (see e.g., Massei et al., 2015). ...
Atlantic cod (Gadus morhua) is a commercially important species, and therefore, understanding the influence of environmental factors and anthropogenic stressors on its early life stages is of considerable relevance. In this contribution, we apply a simple and generic energy-budget framework (DEBkiss) to data for the yolk-feeding stages of cod. The model is capable of explaining the changes in yolk volume, dry weight, oxygen use and body length, simultaneously with a small number of parameters. The calibrated model was subsequently successfully tested with other data sets. Interestingly, the light conditions after hatching affect growth and respiration rates, which is traced to a change in the maintenance costs (linked to swimming activity). Despite the satisfactory performance of the model, several uncertainties remain. Especially the bioenergetics around the point of complete yolk absorption require further attention, which is complicated by the fact that the behaviour around this point differed between data sets. The presented model can be used for exploring effects of stressors on early-life stages of cod, and likely for other aquatic egg-laying species as well.
... Larval exposure to 1.0 µg/l of benzo-apyrene can lead to heritable reductions in egg viability of fathead minnows [14]. Larvae of the different species exposed to phenanthrene and pyrene show slight toxic responses observed as malformation (bilaterally bent chord) toward the end of the exposure period [15]. Early life-stage toxicity to rainbow trout exposed to 9 to 34 µg/l of the C 4 alkyl phenanthrene (1-methyl-3-isopropyl phenanthrene; retene), including hemorrhages (yolk sac, pericardial sac, ocular and cranial tissues), yolk sac edema, skeletal deformities, and mortality [16]. ...
... The types of deformity frequently observed in this study resembled the reported deformities due to certain PAHs that were also detected in WAF of KCO and may possibly be the causative agents as PAHs are known to exert distinct type of abnormalities as described and observed in the present exposure experiments [29]. The embryonic toxicity of PAHs in fish appeared to occur because of sensitivity to planar polycyclic aromatic compounds, high bioaccumulation and limited biotransformation, and exposure during critical developmental periods [15], [37]. ...
Oil pollution in the marine environment is one of the major concerns of the Arabian Gulf States and it can exert a variety of harmful effects in marine organisms and is known to disrupt the embryonic development in fish. Therefore, the lethal and sublethal effects of water-accommodated fraction of Kuwait crude oil (KCO WAF) were examined on embryonated eggs and the larval stages of hamoor (Epinephelus coicoides). The calculated 96h LC 50 was 0.48g oil/l seawater. WAF of KCO produced no adverse effect on hatching of hamoor embryontaed eggs, whereas larvae exposed to the same medium were affected and most of them died by 96-h of exposure at 0.5 and 1.0g KCO/l of seawater. Maximum occurrences of deformity were also found in larvae at these concentrations. The types of deformities were type-A (lordosis-inward curvature of spine or V-shaped) which was followed by type-C (scoliosis-lateral bending of spine), then type-B (kyphosis-hunchback). The types of deformities resembled the reported deformities in literature which can be linked to the presence of polycyclic aromatic hydrocarbons (PAHs) in WAF of KCO. These responses can be used as a bio-indicator of petroleum hydrocarbon pollution in the marine environment.
... The whole-body elimination rate, k 2 , is hypothesized to decrease with increasing K ow , since in theory, the more hydrophobic the chemical, the more energy would be required to mobilize and eliminate it . A regression of k 2 (day − 1 ) with K ow has been proposed for organic nonionic chemicals (Mackay et al., 1992;Spacie and Hamelink, 1982;Feijtel et al., 1997;Petersen and Kristensen, 1998): Spacie and Hamelink (1982) estimated that a = 1.47 and b = 0.414, based on experiments with fish. These coefficients and Eq. ...
... Moreover, Incardona et al. have demonstrated that the toxicity of complex PAH mixtures (including petroleum) depends on the content of tricyclic compounds, namely phenanthrene [42]. Other researchers note that fish embryos and fry at certain stages of development are able to accumulate PAHs, including phenanthrene, in their tissues to micromolar concentrations due to the lipophilicity of oil components and the high permeability of the body integument; this aggravates the toxic effects of these compounds [44]. It should be noted that not only juveniles but also adults of commercial fish species demonstrate PAHs' accumulation in body tissues, which bring us to the issue of the safety of such food products for human health [45]. ...
Every year, more than 1 million t of oil enter sea waters as a result of accidents during production or transportation; not counting oil products that enter the ocean with wastewater. The carcinogenic effect of oil components (such as benzopyrene) has been known since the middle of the 20th century. However, after a major oil spill from the Exxon Valdez tanker in 1989, it has become obvious that oil and its components have a strong toxic effect on the body of fish, and these effects are to a great extent mediated by polycyclic aromatic hydrocarbons (PAHs), in particular, by phenanthrene. The juvenile fish suffer the most from oil spills; they exhibit developmental anomalies when exposed to oil products. However, the influence of oil components is not limited to teratogenic effects and affects all age groups, causing disturbances in the functioning of nervous and cardiovascular systems (and other systems and organs) in adults. PAHs also change hormonal and osmotic regulation. As a result, the largest oil spills threaten populations of important commercial fish species. This review examines the effects of PAHs on the physiology of the main organ systems of fish, including both dysfunctions and malformations in young fish under the influence of petroleum products. Particular attention is paid to the cardiotoxic effects of di- and tricyclic PAHs, which were discovered recently and potentially both cause the death in animals when PAH enter water bodies and underlie developmental disorders.
... Unlike juvenile and mature fish, egg and larval stages lack the ability to avoid contaminated areas [8,57]. Their higher relative content of lipids and surface-area-to-volume ratio makes them more vulnerable to accumulating lipophilic environmental toxins compared to juveniles/adults [63]. Additionally, exposure to crude oil can disrupt critical developmental processes such as patterning and organogenesis [72]. ...
... Инкардоны было продемонстрировано, что токсичность сложных смесей ПАУ (к которым можно отнести нефть) зависит от содержания в них трициклических соединений, а именно фенантрена [42]. Другими исследователями было показано, что эмбрионы и мальки рыб на определенных стадиях развития за счет липофильности компонентов нефти и высокой проницаемости покровов тела способны накапливать в своих тканях ПАУ, включая фенантрен, до микромолярных концентраций, что усугубляет токсическое воздействие этих соединений [44]. Нужно отметить, что не только молодь, но и взрослые особи промысловых видов рыб демонстрируют накопление ПАУ в тканях организма, что ставит вопрос о безопасности подобной пищевой продукции для здоровья человека [45]. ...
The pollution of world ocean is a serious threat to the biodiversity of flora and fauna. One of the most important sources of pollution are oil and oil products – every year more than 1 million tons of oil is spilled into the sea as a result of accidents during oil production or transportation. The teratogenic and carcinogenic effects of such oil components as benzopyrene is well known since the middle of the last century. However, after a large oil spill from “Exxon Valdez” tanker in 1989 it became clear that oil and its components have strong toxic effects in fish organism – and to a large extent these effects are caused by di- and tricyclic aromatic hydrocarbons, in particular phenanthrene. Field research have demonstrated that fish embryo and larvae are the most prone to the effects of oil – and the largest oil spills endanger the populations of important commercial fish species that spawn in this area. This review considers the influence of polycyclic aromatic hydrocarbons (PAH) on the physiology of various organ systems in fish. Particular attention is paid to the cardiotoxic effects of PAH which were recently discovered and which are potentially not only the main cause of animals’ death upon the spill of PAH into water, but also underlie the malformation of other organs.
... The primary route of human exposure to these contaminants is through the consumption of fish [6]. These substances bioaccumulate in food chains [7,8], leading to concentrations in fish tissue that can cause a variety of health problems, especially to vulnerable populations such as children, the elderly, pregnant women, and their unborn children [9]. The northeastern USA has one of the highest consumption rates of fish in the country, so its residents are particularly at risk of contaminant exposure via fish tissue [10]. ...
Many bioaccumulative and toxic contaminants are known to co-occur in fish tissue, yet this covariance has not been explicitly incorporated into model-based risk assessments that inform fish consumption advisories. We utilize available U.S. EPA datasets to statistically model the covariance among contaminant concentrations in fish tissue and the dependence of this covariance on waterbody and watershed conditions. We find that most contaminants positively covary, whether fish were collected in rivers, lakes, or coastal waters. Mercury in lakes and mercury, PFCs, and heptachlor in rivers covary negatively with the other contaminants. While much of the variance and covariance in contaminants can be statistically related to fish characteristics and watershed and waterbody conditions, a large amount remains in model residuals. This implies that single contaminant models, even if highly precise, can misestimate total health risk by neglecting the substantial covariance with other contaminants that is left unmodelled.
... However, the research on the effects of carbon nanomaterials on the fish's early life stages has been performed almost exclusively on zebrafish Danio rerio -a model species with a very short embryonic and larval development. The impact of carbon nanomaterials on the early stages of other fish species remains almost unknown, even though various pollutants, particularly those which can penetrate through the chorion, exert the most toxic effects in fish with the long embryonic stage, such as salmonids (Petersen et al., 1998). Therefore, we have performed an experimental research to evaluate the effects of various carbon nanomaterials on the early life stages of rainbow trout Oncorhynchus mykiss. ...
With the increasing production and the number of potential applications of carbon nanomaterials, mainly from the graphene family, their release into the natural environment, especially to aquatic ecosystems, is inevitable. The aim of the study was to determine the effects of various carbon nanomaterials (graphene nanoflakes (GNF), graphene oxide (GO), reduced graphene oxide (RGO) and silicon carbide nanofibers (NFSiC) in the concentration of 4 mg L-1 on the early life stages of the rainbow trout Oncorhynchus mykiss. The survival rates of O. mykiss were not affected after 36 days of exposure to studied materials, except for RGO, which caused significant mortality of both embryos and larvae compared to the control conditions. Larvae exposed to GO and NFSiC were characterized by a smaller standard body length at hatch, whereas at the end of the experiment, the growth of fish exposed to all materials was accelerated, especially in GO and RGO treatment, in which higher body weight and length were accompanied by lower volume of the yolk sac. Neither the markers of the oxidative damage nor the antioxidant enzymes activities were significantly affected in embryos, newly hatched larvae and larvae after 26-day exposure to studied carbon nanomaterials. Also, no neurotoxic effect expressed by the activity of the whole-body acetylcholinesterase was observed. Nevertheless, the significant increase in the velocity and the overall activity of larvae exposed to GNF (not investigated after exposure to other materials) must be highlighted. The most pronounced effect of RGO might be connected with its large particle size, sharp edges, and the presence of TiO2 nanoparticles. The results indicate for the first time that various carbon nanomaterials potentially released into aquatic ecosystems may have serious developmental implications for the early life stages of salmonid fish.
... The early life stage of fish is considered to be the most sensitive life stage during its lifecycle [6,7], and both the embryonic and larval stages are commonly selected in ...
Oil spill is a major marine environmental pollution issue. Research regarding the long-term effects of oil spills on the early life stage of marine fish is still limited. In this study, the potential adverse impact of crude oil from one oil spill accident which occurred in the Bohai Sea on the early life stages of marine medaka (Oryzias melastigma, McClelland, 1839) was evaluated. A 96-h acute test (larvae) and a 21-d chronic test (embryo–larvae) of water-accommodated fractions (WAFs) from crude oil were conducted, respectively. The results of the acute test showed that only the highest concentration of WAFs (100.00%) significantly affected the mortality of larvae (p < 0.01) and that the 96 h-LC50 was 68.92% (4.11 mg·L-1 expressed as total petroleum hydrocarbons (TPHs)). Larval heart demonstrated histopathological alterations in all WAF-exposed groups. The chronic test results showed that, except for larval mortality, the total hatching success (%)/hatching time of embryos in WAF treatments was not significantly different from those of the control group (p > 0.05), and no malformation was found in surviving larvae after 21 d of exposure. Nevertheless, the exposed embryos and larvae in the highest concentration of WAFs (60.00%) demonstrated significantly reduced heart rate (p < 0.05) and increased mortality (p < 0.01), respectively. Overall, our results indicated that both acute and chronic WAF exposures had adverse impacts on the survival of marine medaka. In the early life stages, the heart of the marine medaka was the most sensitive organ which showed both structural alteration and cardiac dysfunction.
... Studies addressing oxidative status and biotransformation effects of prenatal exposure are notably lacking, albeit oxidative damage, and xenobiotics metabolism responses have been related to contaminant levels in adult elasmobranchs worldwide (Barrera-Garcia et al., 2013;Lyons et al., 2014;Walker et al., 2014;Alves et al., 2016;Cullen et al., 2019;Wosnick et al., 2021;Rodrigues et al., 2022;Alves et al., 2022). Considering that embryonic stages are more vulnerable to contaminants (Petersen and Kristensen, 1998;Jezierska et al., 2009), it is likely that intrauterine exposure might lead to physiological consequences. ...
Coastal elasmobranchs are vulnerable to chemicals mostly due to their k-strategic life history characteristics and high trophic positions. Embryos might be particularly exposed through the maternal offloading of contaminants, possibly leading to disruptions during critical developmental phases. Yet, knowledge on biochemical outcomes of prenatal exposure in elasmobranchs is notably limited. Therefore, we aimed to investigate the effects of prenatal exposure to contaminants in embryos of the critically endangered Brazilian guitarfish, Pseudobatos horkelii. Polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), pharmaceuticals and personal care products, and metals were determined in embryos. Additionally, glutathione S-transferase activity (GST), glutathione (GSH), and metallothionein levels (MT) were analyzed. Finally, lipid peroxidation levels (LPO) and protein carbonyl groups (PCO) were assessed. Embryonic exposure depended on yolk consumption, which was conspicuous in earlier development. We observed a dilution effect of contaminants levels, potentially related to biotransformation of these compounds throughout the embryonic development. Nevertheless, GST was not correlated to contaminant concentrations. The multivariate relationship between antioxidant components (GSH and GST) and LPO and PCO was negative, suggesting the lack of efficient defense of these biomarkers in early development, leading to oxidative damage. In this context, our results indicate that prenatal exposure to contaminants might impact the redox status in embryos of P. horkelii, leading to oxidative damage. Furthermore, metal concentrations influenced MT levels, suggesting this as a potential detoxification pathway in this species.
... In Atlantic cod (Gadus morhua), a close relative to haddock, phenanthrene, and other more hydrophobic compounds had not yet reached a steady state in larval exposures aer 72 hours of exposures at 6.5°C. 35 Accordingly, we expected that the test compounds in the present study would also be in the uptake phase and would not yet have reached a steady-state equilibrium. More hydrophobic chemicals will have higher bioconcentration at equilibrium, ignoring metabolism; however, a steady state was not reached in this study. ...
Tricyclic polycyclic aromatic hydrocarbons (PAHs) are believed to be the primary toxic components of crude oil. Such compounds including phenanthrene are known to have direct effects on cardiac tissue, which lead to malformations during organogenesis in early life stage fish. We tested a suite of 13 alkyl-phenanthrenes to compare uptake and developmental toxicity in early life stage haddock (Melanogrammus aeglefinus) embryos during gastrulation/organogenesis beginning at 2 days post fertilization via passive dosing. The alkyl-phenanthrenes were tested at their solubility limits, and three of them also at lower concentrations. Measured body burdens were linearly related to measured water concentrations. All compounds elicited one or more significant morphological defects or functional impairment, such as decreased length, smaller eye area, shorter jaw length, and increased incidence of body axis deformities and eye deformities. The profile of developmental toxicities appeared unrelated to the position of alkyl substitution, and gene expression of cytochrome 1 a (cyp1a) was low regardless of alkylation. Mortality and sublethal effects were observed below the expected range for baseline toxicity, thus indicating excess toxicity. Additionally, PAH concentrations that resulted in toxic effects here were far greater than when measured in whole crude oil exposures that cause toxicity. This work demonstrates that, while these phenanthrenes are toxic to early life stage fish, they cannot individually account for most of the developmental toxicity of crude oil, and that other compounds and/or mixture effects should be given more consideration.
... At least eight hours is recommended for practical considerations. Research demonstrates that while specific compound uptake rates are influenced by many factors (e.g., organism life stage, organism species, logk ow of the compound, binding competition with dissolved organic matter, and others) in controlled laboratory conditions rapid accumulation occurs for two and three ringed PACs within the first eight hours of exposure (Morgan and Warshawsky 1977;Spacie et al. 1983;Duxbury et al. 1997;Petersen and Kristensen 1998). Specific research aims may require a different compound and light exposure periods. ...
Photo-induced toxicity of petroleum products and polycyclic aromatic compounds (PACs) is the enhanced toxicity caused by their interaction with ultraviolet radiation and occurs by two distinct mechanisms: photosensitization and photomodification. Laboratory approaches for designing, conducting, and reporting of photo-induced toxicity studies are reviewed and recommended to enhance the original Chemical Response to Oil Spills: Ecological Research Forum (CROSERF) protocols which did not address photo-induced toxicity. Guidance is provided on conducting photo-induced toxicity tests, including test species, endpoints, experimental design and dosing, light sources, irradiance measurement, chemical characterization, and data reporting. Because of distinct mechanisms, aspects of photosensitization (change in compound energy state) and photomodification (change in compound structure) are addressed separately, and practical applications in laboratory and field studies and advances in predictive modeling are discussed. One goal for developing standardized testing protocols is to support lab-to-field extrapolations, which in the case of petroleum substances often requires a modeling framework to account for differential physicochemical properties of the constituents. Recommendations are provided to promote greater standardization of laboratory studies on photo-induced toxicity, thus facilitating comparisons across studies and generating data needed to improve models used in oil spill science.
... Embryos are thought to absorb PAHs by passive diffusion through the chorion (Hodson, 2017). The rate of accumulation is generally lower in embryos compared to larvae due to a lower rate of transport through the chorion compared to larval gills (Petersen and Kristensen, 1998). Hydrophobic chemicals have been shown to partition into the oil globule in eggs of Atlantic croaker (Micropogonias undulates) (Ungerer and Thomas, 1996). ...
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants that can enter aquatic environments through runoff, atmospheric deposition, accidental discharge, and oil spills. These compounds can be oxidized photochemically or biologically into oxygenated PAHs (oxy-PAHs) which have been shown to be more toxic compared to parent PAHs. The polar properties of oxy-PAHs increase their mobility within the environment which increases the risk of exposure to fauna and flora compared to parent PAHs. Regioselective toxicity has been observed in several oxy-PAHs and the oxidation state of the oxygen on a specific PAH can have dramatic impacts on the toxicity. Previous studies have found that exposure to hydroxychrysenes at critical developmental time-points in fish models impairs red blood cell concentrations in a regioselective manner, with 2-hydroxychrysene (2-OHCHR) being more potent than 6-hydroxychrysene (6-OHCHR). The mechanisms of toxicity of oxy-PAHs are largely unknown and we aimed to characterize the pathways of toxicity of 2- and 6-OHCHR in fish embryos. Our first aim was to characterize the toxic effects in Japanese medaka embryos and to find a sensitive window of development to hydroxychrysenes. We found that 2-OHCHR caused anemia and morality in medaka embryos in contrast to in zebrafish embryos, where 2-OHCHR caused only anemia and 6-OHCHR only caused mortality. A sensitive window to 2-OHCHR toxicity was found between 52-100 hpf which closely coincided with liver development. This led us to our second aim, exploring the metabolism and toxicokinetics of the hydroxychrysenes. We found that although 6-OHCHR was taken up 97.2% ± 0.18 more rapidly than 2-OHCHR, it was also eliminated 57.7% ± 0.36 faster as a glucuronide conjugate. Pretreatment with the general cytochrome P450 inhibitor ketoconazole reduced anemia by 96.8% ± 3.19 and mortality by 95.2% ± 4.76 of 2-OHCHR treatments. In addition, formation of the 1,2-catechol was also reduced by 64.4% ± 2.14. However, while pretreatment with the UGT inhibitor nilotinib reduced glucuronidation of 2-OHCHR by 52.4% ± 2.55 and of 6-OHCHR by 63.7% ± 3.19, it did not alter toxicity for either compound. These results indicated that CYP mediated activation, potentially to the oxidatively active metabolite 1,2-catechol, may be driving the isomeric differences in toxicity. Previous studies have found 2-OHCHR to be a four-fold more potent aryl hydrocarbon receptor (AhR) agonist compared to 6-OHCHR. Therefore, in aim 3, we explored the role of the and oxidative stress in 2-OHCHR toxicity. While treatments with the AhR agonists PCB126 and 2-methoxychrysene (2-MeOCHR) did not cause significant anemia or mortality, pretreatments with AhR antagonist CH-223191 reduced anemia by 97.2% ± 0.84 and mortality by 96.6% ± 0.69. AhR inhibition was confirmed by a significant reduction (91.0% ± 9.94) in EROD activity. Thiobarbituric acid reactive substances (TBARS) concentrations were 32.9% ± 3.56 higher (p<0.05) in 2-OHCHR treatments at 100 hpf compared to controls, indicating oxidative stress. Staining with 2’,7’-Dichlorofluorescin diacetate (DCFDA) revealed 42.6% ± 2.69 of embryos exhibiting high concentrations of ROS in caudal tissues, which is a site for embryonic hematopoiesis. Both muscle and skeletal tissues were affected, as well as some caudal vasculature. Overall, our findings indicate that AhR may mediate 2-OHCHR toxicity, upregulating CYP and potentially forming the 1,2-catechol that generates ROS in the embryos within caudal tissues, potentially disrupting hematopoiesis leading to anemia and subsequent mortality. Further studies should investigate additional key events and construct adverse outcome pathways for oxy-PAHs.
... Also the hatching rate was similar in all MPs treatments. The lack of observed effects of exposure to various MPs on various developmental parameters measured directly in the embryos is not entirely surprising since embryos are considered well protected from surrounding environment by the chorion (Van Leeuwen et al., 1985), and the migration rate of xenobiotics through the chorion of embryo is lower compared to the transport across the gill epithelium of larvae (Petersen and Kristensen, 1998). It is unlikely that microplastics used in the present study penetrated the chorion since 150-180 μm was the smallest MPs size fraction applied, while the chorionic pores of salmonid embryos are 0.5-0.8 ...
Plastic pollution is recognized as serious threat to aquatic organisms. The aim of this research was to determine the effect of environmentally realistic concentrations of various microplastics (MPs) on survival, growth, development and induction of endocrine, geno- and cytotoxic responses in the early life stages of rainbow trout Oncorhynchus mykiss. Fish were exposed for 69-days, from embryos at eyed-stage to mobile yolk-sac larvae, to pre-production pellets (3000 μm; polystyrene - PS and polyethylene terephthalate - PET). Additionally, since salmonid larvae are particularly exposed to light polymers after swimming up from the bottom, fish were also exposed to PE microspheres (150–180 μm; polyethylene - PE) for both long (69-days, from embryos at eyed-stage) and short period (29 days, from larvae 3 weeks after hatching) to test the development stage-related effect on the growth parameters and fitness. Hatching success, rate and the survival of larvae did not differ among treatments. Although some alterations were found in the length gain after the long-term exposure and in the yolk-sac exhaustion rate in all PE treatments, the final size of larvae did not differ from the respective controls. PE-treated larvae have shown elevated corticosterone concentrations being significantly higher in fish exposed from the embryo stage. It was indicated for the first time that mobile yolk-sac larvae ingested MPs (up to 24% of larvae contained microspheres). No changes were recorded in cytotoxicity endpoints in any of the treatments, but exposure to PS pellets resulted in significantly higher frequencies of genotoxicity endpoints compared to the control treatment. This effect and aforementioned alterations in PE-treated larvae might result from the exposure to toxic MPs leaches. The fact that selected PAHs' levels reached the highest values in PS pellets and PE microspheres must be underlined.
... In a laboratory study, Addison and Willis (1978) detected p,p'-DDMU in rainbow trout fry (Oncorhynchus mykiss) after exposure to p, p'-DDD, suggesting in vivo biotransformation of p,p'-DDD to p,p'-DDMU in the fish. Considering that liver is the major metabolism organ for exogenous pollutants while this metabolism capacity is generally low in eggs due to lack of the metabolism enzymes (Petersen and Kristensen, 1998), the concentration ratios of p,p'-DDMU to p,p'-DDD between the liver and the eggs may provide insight into the possible biotransformation of p,p'-DDMU in our fish. We found that the ratios calculated in the liver were significantly higher than those estimated in the eggs, both for the NS (p = 0.002) and CC (p = 0.04) (Fig. S1of the supplementary Data); implying that the p,p'-DDMU in the present fish may be originated, at least in part, from the biotransformation of p, p'-DDD. ...
While the secondary metabolites of DDT such as 2,2-bis(chlorophenyl)-1-chloroethylene (DDMU) and 2,2-bis(chlorophenyl)methane (DDM) have been detected in the environment for several decades, knowledge is extremely limited on their bioaccumulation characteristics. Here, we reported the bioaccumulation and maternal transfer of p,p′-DDMU and p,p′-DDM in two wild fishes, i.e., the northern snakehead (Channa argus) and crucian carp (Carassius auratus), from a DDT contaminated site in South China. The hepatic concentrations of p,p′-DDMU and p,p′-DDM in the fish were up to 549 and 893 ng/g lipid weight, contributing 5.3% and 3.2% in average to ΣDDXs (the sum concentrations of DDT and its 6 metabolites), respectively. The residues of p,p′-DDMU and p,p′-DDM in the fish exhibited interspecific and intraspecific variations, resulting from the differences in lipid content, sex, and body sizes (length and mass) between or within species. Both p,p′-DDMU and p,p′-DDM were consistently detected in the fish eggs, demonstrating their maternal transfer in female fish. The mean eggs to liver lipid-normalized concentration (E/L) ratios of p,p′-DDMU and p,p′-DDM were 0.98 and 1.77 in the northern snakehead, 0.35 and 0.01 in crucian carp, respectively; which were comparable to or even exceeded those of DDT and its major metabolites calculated in the same individual. Statistical analyses of the data showed that the E/L ratios were positively correlated with body sizes of the fish, but negatively correlated with the hepatic concentrations of p,p′-DDMU and p,p′-DDM in females; suggesting the influences of fish sizes and the mother body residues on their maternal transfer efficiencies.
... The latter descriptor, however, only applies to non-ionisable or neutral compounds. Yet, log P is known to determine a substance's uptake by diffusion processes through biomembranes (Hawker and Connell, 1986;Gobas et al., 1989;Petersen and Kristensen, 1998;de Koning et al., 2015). Therefore, the degree to which a compound exerts toxicity has been shown to be strongly related to its log p value, both in fish (Sachidanandan et al., 2008;Padilla et al., 2012) and microtoxicity assays (Gough et al., 1994). ...
Environmental risk assessments of organic chemicals usually do not consider pH as a key factor. Hence, most substances are tested at a single pH only, which may underestimate the toxicity of ionisable substances with a pKa in the range of 4–10. Thus, the ability to consider the pH-dependent toxicity would be crucial for a more realistic assessment. Moreover, there is a tendency in acute toxicity tests to focus on mortality only, while little attention is paid to sublethal endpoints. We used Danio rerio embryos exposed to ten ionisable substances (the acids diclofenac, ibuprofen, naproxen and triclosan and the bases citalopram, fluoxetine, metoprolol, propranolol, tramadol and tetracaine) at four external pH levels, investigating the endpoints mortality (LC50) and heart rate (EC20). Dose-response curves were fitted with an ensemble-model to determine the true uncertainty and variation around the mean endpoints. The ensemble considers eight (heart rate) or twelve (mortality) individual models for binominal and Poisson distributed data, respectively, selected based on the Akaike Information Criterion (AIC). In case of equally good models, the mean endpoint of all models in the ensemble was calculated, resulting in more robust ECx estimates with lower ‘standard errors’ as compared to randomly selected individual models.
We detected a high correlation between mortality (LC50) at 96 hpf and reduced heart rate (EC20) at 48 hpf for all compounds and all external pH levels (r = 0.98). Moreover, the observed pH-dependent effects were strongly associated with log D and thus, likely driven by differences in uptake (toxicokinetic) rather than internal (toxicodynamic) processes.
Prospectively, the a priori consideration of pH-dependent effects of ionisable substances might make testing at different pH levels redundant, while the endpoint of mortality might even be replaced by a reliable sublethal proxy that would reduce the exposure, accelerating the evaluation process.
... The larvae of zebrafish at 7 days post fertilization (dpf) are only~4 mm in length [18] with a dry mass of3 9 μg [19]. They are sufficiently small to be arrayed into 96-well plates for high-throughput screening of chemical libraries to detect potentially therapeutic drugs [20]. ...
Background
Early-onset familial Alzheimer’s disease (EOfAD) is promoted by dominant mutations, enabling the study of Alzheimer’s disease (AD) pathogenic mechanisms through generation of EOfAD-like mutations in animal models. In a previous study, we generated an EOfAD-like mutation, psen1 Q96_K97del , in zebrafish and performed transcriptome analysis comparing entire brains from 6-month-old wild type and heterozygous mutant fish. We identified predicted effects on mitochondrial function and endolysosomal acidification. Here we aimed to determine whether similar effects occur in 7 day post fertilization (dpf) zebrafish larvae that might be exploited in screening of chemical libraries to find ameliorative drugs.
Results
We generated clutches of wild type and heterozygous psen1 Q96_K97del 7 dpf larvae using a paired-mating strategy to reduce extraneous genetic variation before performing a comparative transcriptome analysis. We identified 228 differentially expressed genes and performed various bioinformatics analyses to predict cellular functions.
Conclusions
Our analyses predicted a significant effect on oxidative phosphorylation, consistent with our earlier observations of predicted effects on ATP synthesis in adult heterozygous psen1 Q96_K97del brains. The dysregulation of minichromosome maintenance protein complex (MCM) genes strongly contributed to predicted effects on DNA replication and the cell cycle and may explain earlier observations of genome instability due to PSEN1 mutation. The upregulation of crystallin gene expression may be a response to defective activity of mutant Psen1 protein in endolysosomal acidification. Genes related to extracellular matrix (ECM) were downregulated, consistent with previous studies of EOfAD mutant iPSC neurons and postmortem late onset AD brains. Also, changes in expression of genes controlling iron ion transport were observed without identifiable changes in the prevalence of transcripts containing iron responsive elements (IREs) in their 3′ untranslated regions (UTRs). These changes may, therefore, predispose to the apparent iron dyshomeostasis previously observed in 6-month-old heterozygous psen1 Q96_K97del EOfAD-like mutant brains.
... A substantial effort was required to evaluate and standardize the invertebrate BCF data because of inconsistencies in the reporting units (wet, dry, and lipid-basis) and lack of ancillary data on organism composition (e.g., lipid and water contents) and other study details. A study reporting PHE bioaccumulation in fish eggs and larvae was found (Petersen and Kristensen 1998); however, these PHE data (see Supplemental Data Section S4, Table S4-7) are excluded from the B assessment because toxicity was observed in all experiments with larvae (malformation; bilaterally bent chorda) and the exposure concentrations were very high (within 10% of water solubility). The exclusion of these data is consistent with 1) a previous summary of bioaccumulation data for PAHs where data from early life stages were deemed "Not Reliable" (Bleeker and Verbruggen 2009) and 2) OECD 305 testing guidelines (OECD 2012). ...
Bioaccumulation (B) assessment is challenging because there are various B‐metrics from laboratory and field studies, various criteria and thresholds for classifying bioaccumulative (“B”), very bioaccumulative (“vB”), and non‐bioaccumulative (“nB”) chemicals, as well as inherent variability and uncertainty in the data. These challenges can be met using a weight of evidence (WoE) approach. The Bioaccumulation Assessment Tool (BAT) provides a transparent WoE assessment framework that follows Organisation for Economic Coordination and Development (OECD) principles for performing a WoE analysis. The BAT guides an evaluator through the process of data collection, generation, evaluation, and integration of various lines of evidence (LoE) (i.e., B‐metrics) to inform decision‐making. Phenanthrene (PHE) is a naturally occurring chemical for which extensive B and toxicokinetics data are available. A B assessment for PHE using the BAT is described that includes a critical evaluation of 74 measured in vivo LoE for fish and invertebrate species from laboratory and field studies. The number of LoE are reasonably well balanced across taxa (i.e., fish and invertebrates) and the different B‐metrics. Additionally, in silico and in vitro biotransformation rate estimates and corresponding model predicted B‐metrics are included as corroborating evidence. Application of the BAT provides a consistent, coherent, and scientifically‐defensible WoE evaluation to conclude that PHE is not bioaccumulative (“nB”) as the overwhelming majority of the bioconcentration, bioaccumulation and biomagnification metrics for both fish and invertebrates are below regulatory thresholds. An analysis of the relevant data using fugacity ratios is also provided showing phenanthrene does not biomagnify in aquatic food webs. The critical review identifies recommendations to increase the consistency of B assessments, such as improved standardization of B testing guidelines, data reporting requirements for invertebrate studies, and consideration of temperature and salinity effects on certain B‐metrics. This article is protected by copyright. All rights reserved.
... Therefore, dispersed oil should be included in realistic oil dosing (Nordtug et al., 2011). Early life stages of fish are particularly vulnerable to crude oil due to their critical developmental window, limited mobility, transparency, high relative content of lipids and primitive metabolic capacities (Petersen and Kristensen, 1998). It is now well established that fish embryos exposed to trace levels of crude oil exhibit a common syndrome of developmental toxicity (Incardona, 2017;Pasparakis et al., 2019). ...
To further understand the complexity of developmental toxicity of dispersed oil and importance of exposure timing on fish early life stages, Atlantic halibut (Hippoglossus hippoglossus) were exposed to environmentally relevant concentrations through two embryonic developmental windows: the first period occurred during the epiboly process (named as “early embryonic exposure”) and the second period overlapped the ontogenesis and cardiogenesis processes (named as “late embryonic exposure”). Following 72 hours oil exposure, embryos were transferred to clean seawater and a toxicity screening was performed in the yolk-sac larvae until first-feeding stages (56 days). The current study demonstrated that the exposure timing is essential for the development of toxic effects of crude oil in Atlantic halibut. Neither embryonic exposures (early or late) showed notable acute toxicity during exposure, yet both showed global latent teratogenic effects during yolk sac stages. Fish exposed during organogenesis (late) displayed stronger and more severe toxic effects than fish exposed during epiboly process (early), including reduced condition, severe craniofacial deformities and cardiovascular disruptions. The uptake level of polycyclic aromatic hydrocarbons into larval tissue and metabolic activity were greater following the late embryonic exposure and remained high during the depuration period at the highest exposure concentration. Overall, the long yolk sac stage development timing of Atlantic halibut makes this species a good candidate for evaluation of embryonic crude oil toxicity and its mechanisms.
... However, dibenzothiophene and dibenzofuran, structurally similar 3-ring heterocyclic aromatic hydrocarbons that differ only in their molecular substitution, had a very similar time-dependent onset of immobilization and mortality. Previous studies have reported an inverse linear relationship between the log of the first-order elimination rate and the log K OW for various nonionic organic compounds (Spacie and Hamelink 1982;Petersen and Kristensen 1998;Lee et al. 2002), ...
Aquatic exposures to aromatic compounds (ACs) may be important contributors to biological effects of oil spills. This study examined the acute toxicity of 11 ACs and three binary AC mixtures on Stage I American lobster larvae using a passive dosing test design. The ACs investigated covered a range of classes and log Kow (2.5‐5.5). Silicone O‐rings were used to partition ACs into seawater and maintain stable exposures. Exposed lobster larvae were assessed for mobility and survival at 3, 6, 12, 24, 36 and 48 hours. Fluorometry and GC‐MS measurements confirmed well defined substance exposures. Expressing lethality in terms of chemical activities (LA50) yielded values between 0.01‐0.1 consistent with a baseline mode of action. Analysis of time‐dependent L/EC50 were used to determine incipient values. An expected linear relationship between the incipient log L/EC50 and log Kow was fit to the empirical toxicity data to derive critical target lipid body burdens (CTLBB) for immobilization and lethality endpoints. CTLBBs indicate that American lobster larvae fall on the sensitive end of the acute species sensitivity distribution. AC toxicity data was used to successfully predict toxicity of binary mixtures assuming additive toxicity. The observed time‐dependent toxicity was inversely related to Log Kow and occurred more quickly than reported previously. Results contribute to improving models for predicting oil spill impacts on American lobster larvae populations. This article is protected by copyright. All rights reserved.
... Early life stages drift and have no opportunity to avoid contaminated areas compared to juvenile and mature fish (Carroll et al., 2018;Olsen et al., 2010). Relative content of lipids and surfacearea-to-volume ratio are higher in early life stages compared to juveniles/adults, making them more susceptible to accumulation of lipophilic environmental toxicants (Petersen and Kristensen, 1998). Finally, critical developmental processes like patterning and organogenesis can be disrupted by crude oil exposure (Incardona, 2017;Pasparakis et al., 2019;Sørhus et al., 2017). ...
Early life stages of fish are highly sensitive to crude oil exposure and thus, short term exposures during critical developmental periods could have detrimental consequences for juvenile survival. Here we administered crude oil to Atlantic haddock (Melanogrammus aeglefinus) in short term (3-day) exposures at two developmental time periods: before first heartbeat, from gastrulation to cardiac cone stage (early), and from first heartbeat to one day before hatching (late). A frequent sampling regime enabled us to determine immediate PAH uptake, metabolite formation and gene expression changes. In general, the embryotoxic consequences of an oil exposure were more severe in the early exposure animals. Oil droplets on the eggshell resulted in severe cardiac and craniofacial abnormalities in the highest treatments. Gene expression changes of Cytochrome 1 a, b, c and d (cyp1a, b, c, d), Bone morphogenetic protein 10 (bmp10), ABC transporter b1 (abcb1) and Rh-associated G-protein (rhag) were linked to PAH uptake, occurrence of metabolites of phenanthrene and developmental and functional abnormalities. We detected circulation-independent, oil-induced gene expression changes and separated phenotypes linked to proliferation, growth and disruption of formation events at early and late developmental stages. Changes in bmp10 expression suggest a direct oil-induced effect on calcium homeostasis. Localized expression of rhag propose an impact on osmoregulation. Severe eye abnormalities were linked to possible inappropriate overexpression of cyp1b in the eyes. This study gives an increased knowledge about developmentally dependent effects of crude oil toxicity. Thus, our findings provide more knowledge and detail to new and several existing adverse outcome pathways of crude oil toxicity.
... The similar accumulation levels observed from both exposure routes were also reflected in the log BCF values which showed only a minor difference between aqueous (log BCF = 3.72) and dietary exposure (log BCF = 3.58) routes. Coral BCF estimated in this experiment is a factor higher than reported log BCFs for nematodes (2.92) (Spann et al., 2015), freshwater isopods (2.8 ± 0.5) (Van Hattum and Cid Montanes, 1999) and aligns closer to those estimated for certain copepod species (3.80, Pseudodiaptomus marinus (Arias et al., 2016); 3.18 Calanus finimarichus (Jensen et al., 2012)) and larval stages of fish (3.90, Danio rerio) (Petersen and Kristensen, 1998;Xia et al., 2015). The coral BCF is lower than octanol-water partition co-efficient of phenanthrene (K ow = 4.53) indicating the likelihood of some elimination mechanisms (Jensen et al., 2012). ...
Polycyclic aromatic hydrocarbons (PAHs) are widespread pollutants in marine ecosystems including threatened and potentially sensitive coral reefs. Lower organisms such as phytoplankton, known to bioconcentrate PAHs, could serve as potential entry points for these chemicals into higher trophic levels. Here, we present a novel method using a ¹³C-labelled PAH and cavity ring-down spectroscopy (CRDS) to investigate accumulation, uptake rates and trophic transfer of PAHs in corals, which are key organisms to sustain biodiversity in tropical seas. We quantified the accumulation of ¹³C-phenanthrene in the marine microalga Dunaliella salina, and in the coral Acropora millepora after diffusive uptake from seawater or dietary uptake via labelled D. salina. Additionally, we monitored the photophysiological health of D. salina and A. millepora during phenanthrene exposure by pulse-amplitude modulation (PAM) fluorometry. Dose-dependent accumulation of ¹³C-phenanthrene in the microalga showed a mean bioconcentration factor (BCF) of 2590 ± 787 L kg⁻¹ dry weight. Corals accumulated phenanthrene from both exposure routes. While uptake of ¹³C-phenanthrene in corals was faster through aqueous exposure than dietary exposure, passive diffusion showed larger variability between individuals and both routes resulted in accumulation of similar concentrations of phenanthrene. The ¹³C-PAH labelling and analysis by CRDS proved to be a highly sensitive method. The use of stable isotopic label eliminated additional toxicity and risks by radioactive isotopic-labelling, and CRDS reduced the analytical complexity of PAH (less biomass, no extraction, fast analysis). The simultaneous, precise quantification of both carbon content and ¹³C/¹²C ratio (δ¹³C) enabled accurate determination of ¹³C-phenanthrene accumulation and uptake rate. This is the first study to provide empirical evidence for accumulation of phenanthrene in a phytoplankton-coral food chain.
... The correlation coefficient between these two pairs of data sets was 0.96, which indicates that the variability of the parameters (K BL , CR L , ILC 50L ) is strongly related to the variability of f L . Naturally, f L variability is found among organs (Bertelsen et al. 1998), life stages (Petersen and Kristensen 1998), species (Petenuci et al. 2016), and time and season (Oliver et al. 2015;Petenuci et al. 2016) and may influence BTR L . The BTR L of aquatic organisms were highly related to neutral lipid fraction (Hendriks et al. 2005) and well described by linear regression models. ...
The evaluation of bioconcentration, toxicity, and hazard (BTH) of persistent lipophilic organic compounds (LOCs) are generally performed as separate rather than integrated assessments. There are adequate data sets in the literature for chlorobenzenes (CBs) consisting of (a) concentrations in aquatic biota (CB) and water (Cw) in the natural environment, (b) laboratory-derived bioconcentration factors (KB) and field concentration ratios (CR), the field equivalent factor of KB, (c) measured internal lethal concentrations (ILC50) and model estimated ILC50 calculated from KB and lethal concentrations (LC50), and (d) calculated hazard quotients in aquatic biota (HQB) and in water (HQW). However, there have been no integrated studies of those parameter values based on the respective lipid-based parameters (CBL, KBL, CRL, ILC50L, HQBL) performed. This study utilized the lipid-based parameters for CBs; a group of widely occuring, bioaccumulative, and toxic LOCs, and integrated those parameters into a bioconcentration-toxicity-hazard (BTHL) index. The values of the parameters were obtained from selected literature with known lipid contents of the aquatic biota. The results showed that the laboratory derived bioconcentration factors, KBLs, were comparable to the corresponding field based factors, CRLs, and the measured internal lethal concentrations, ILC50L, showed comparable values with the estimated ones. The integrated BTHL index was less than an order of magnitude or moderately acceptable for the assessment of variability, uncertainty, and predictive power of the index. This integrated assessment can be used to support decision making dealing with CBs in specific and LOCs in general, both in regional and global aquatic environments.
... A total of 267 individual lipids were identified and quantified by UHPLC/TOFMS high-throughput lipidomic analysis in control and 6 mg/L BPA exposed samples (Supplementary Table ST4 (Hachicho et al., 2015;Petersen and Kristensen, 1998); therefore, we can conclude that all the major lipids were measured. Fig. F2A presents relative abundances for all 267 individual lipids in each sample. ...
Bisphenol A (BPA; 4,4'-(propane-2,2-diyl)diphenol) has been shown to act as an obesogen and to disrupt lipid metabolism in zebrafish eleutheroembryos (ZE). To characterize the consequences of this disruption, we performed a detailed lipidomic study using ZE exposed to different BPA concentrations (0, 4, 6 and 8 mg/L of BPA) from day 2 to up to day 6 post fertilization (dpf). Total lipids at 4, 5 and 6 dpf were extracted by Folch method and analyzed by high-performance thin layer chromatography (HPTLC) as wide-range preliminary screening. Selected conditions (0 and 6 mg/L of BPA) were used to obtain a high-quality lipid profile using ultra high-performance liquid chromatography/time-of-flight mass spectrometry (UHPLC-TOFMS). BPA exposed ZE exhibited increased amounts of triglycerides (TG), diglycerides (DG), phosphatidylcholines (PC) and phosphatidylinositols (PI), regarding the control group. Analysis of time- and BPA exposure-related patterns of specific lipid species showed a clear influence of unsaturation degree (mostly in DG and PC) and/or fatty acid chain length (mostly in TG and PC derivatives) on their response to the presence of BPA. A decreased yolk-sac and energy consumption in exposed individuals appeared as the main reason for the observed BPA-driven effects. Integration of these results with previous morphological, biochemical, transcriptomic, metabolomic and behavioral data suggests a disruption of different signalling pathways by BPA that starts at very low BPAconcentrations, whose effects propagate across different organization levels, and that cannot be only explained by the relatively weak estrogenic effect of BPA.
... jaw defects, small eyes, body axis deformations) were all downstream of reduced cardiac output in developing embryos (Incardona et al. 2004). Extensive studies have now demonstrated that PAH mixtures containing nanomolar concentrations of Phe are bioconcentrated to micromolar concentrations in fish embryos (Petersen & Kristensen, 1998). Corresponding cardiotoxicity syndromes range from outright heart failure and larval mortality at the high end to subtle heart malformation with pathological hypertrophy and reduced cardiorespiratory performance at the low end (Incardona et al. 2004(Incardona et al. , 2005(Incardona et al. , 2009). ...
Air pollution is associated with detrimental effects on human health, including decreased cardiovascular function. However, the causative mechanisms behind these effects have yet to be fully elucidated. Here we review the current epidemiological, clinical and experimental evidence linking pollution with cardiovascular dysfunction. Our focus is on particulate matter (PM) and the associated low molecular weight polycyclic aromatic hydrocarbons (PAHs) as key mediators of cardiotoxicity. We begin by reviewing the growing epidemiological evidence linking air pollution to cardiovascular dysfunction in humans. We next address the pollution‐based cardiotoxic mechanisms first identified in fish following the release of large quantities of PAHs into the marine environment from point oil spills (e.g. Deepwater Horizon). We finish by discussing the current state of mechanistic knowledge linking PM and PAH exposure to mammalian cardiovascular patho‐physiologies such as atherosclerosis, cardiac hypertrophy, arrhythmias, contractile dysfunction and the underlying alterations in gene regulation. Our aim is to show conservation of toxicant pathways and cellular targets across vertebrate hearts to allow a broad framework of the global problem of cardiotoxic pollution to be established. AhR; Aryl hydrocarbon receptor. Dark lines indicate topics discussed in this review. Grey lines indicate topics reviewed elsewhere. image
... To quantify the internal BPA concentration, 20 zebrafish larvae at 5 dpf were exposed to 10 and 20 mM BPA in medium for 10, 30, 60, 90, or 120 min. Kinetic bioconcentration factors (BCF) were calculated from the ratio of average BPA concentration in fish (C f ) to the average concentration in larval medium (C w ) at each incubation time according to Petersen et al. (Petersen and Kristensen, 1998). ...
Bisphenol A (BPA) is a chemical monomer widely used in the production of hard plastics for food containers and personal items. Through improper industrial control and disposal, BPA has become a pervasive environmental contaminant, and toxicological studies have shown potent xenobiotic endocrine disruptor activity. Prenatal exposure in particular can lead to infertility and nervous system disorders characterized by behavioral aggression, depression, and cognitive impairment, thus necessitating careful hazard assessment.
In this study, we evaluated BPA accumulation rate, blood-brain barrier (BBB) permeability, lethality, cardiotoxicity, behavioral effects, and impacts on multiple neurochemical pathways in zebrafish larvae. The bioconcentration factor (BCF) ranged from 1.95 to 10.0, resulting in a high rate of accumulation in the larval body. Also, high BBB permeability allowed BPA to accumulate at similar rates in both zebrafish and adult mouse (blood to brain concentration ratios of 3.2–6.7 and 1.8 to 5.5, respectively). In addition, BPA-exposed zebrafish larvae exhibited developmental deformities, reduced heart rate, and impaired behavioral patterns, including decreased total distance traveled, slower movement velocity, and altered color-preference. These impairments were associated with inhibition of the phenylalanine to dopamine synthesis pathway and an imbalance between excitatory and inhibitory neurotransmitter systems. Our results suggest that behavioral alteration in BPA-exposed zebrafish result from high accumulation and ensuing dysregulation of serotonergic, kynurenergic, dopaminergic, cholinergic, and GABAergic neurotransmitter systems. In conclusion, similarities in toxic responses to mammalian models highlight the utility of the zebrafish larva as a convenient model for screening environmental toxins.
... Furthermore, earlier research suggests that different life stages have different metabolic capacity, with varying V max and K m values (Fitzsimmons et al., 2007). However, also comparable differences in uptake rates have been observed (Petersen and Kristensen, 1998), potentially resulting in comparable BCF values across life stages. Because of the comparable outcomes across life stages, the use of egg/larval stages might become of future interest to replace the standard in vivo bioconcentration test with non-protected in vivo systems (Sanz-Landaluze et al., 2015). ...
The fish bioconcentration factor (BCF) is an important aspect within bioaccumulation assessments. Several factors have been suggested to influence BCF values – including species, developmental stage, mixture exposure, and calculation method. However, their exact contribution to variance in BCF values is unknown. Within this study we assessed the relative impact of these test characteristics on BCF values and analyzed the reproducibility of aquatic exposure bioconcentration tests.
Linear mixed effects analyses were performed on a newly develop database to investigate the relationship between the response variable (i.e. lipid normalized log BCF values) and several test characteristics as fixed effects.
Lower BCF values were observed for substances that were simultaneously applied with high molecular weight polycyclic aromatic hydrocarbons compared to single substance exposure (with an average difference of −0.81 log BCF). Also, lower BCFs upon kinetic determination were observed compared to steady-state BCFs (log BCF -0.27), and lower BCFs for species from the Ostariophysi subcohort level (log BCF -0.17 to −0.15). In addition, data analysis showed high variation within BCF values for single substances (average SD = log BCF 0.21), which questions the robustness of the current bioaccumulation assessments. For example, the 95% confidence range of a BCF value of 2500 ranges from 953 (‘not-bioaccumulative’) to 6561 (‘very bioaccumulative’).
Our results show that the use of one single BCF leads to a high uncertainty in bioaccumulation assessments. We strongly recommend that within future bioconcentration studies, the used experimental design and test conditions are described in detail and justified to support solid interpretation.
... Developmental stage and fish size can have a significant effect on the impact of a toxicant. The time required to accumulate toxicants is likely shorter during early life stages than in later stages due to the shorter diffusion distances involved (Petersen and Kristensen, 1998). The sensitivity of embryonic stages to chemical-induced adverse effects is substantially influenced by specific 5 developmental events, e.g., organogenesis (Honkanen, 2004). ...
The enhanced expression of heat shock proteins (HSPs) and metallothionein (MT) can
be detected in response to many environmental stressors, including exposure to heavy metals. We identified partial mRNA sequences for beta2-microglobulin (ß2m), heat shock cognate 70 kDa protein (HSP70), and MT in embryos of the African catfish Clarias gariepinus (Burchell, 1822). Levels of these transcripts were assessed using reverse-transcription quantitative polymerase chain reaction (RT-QPCR) after embryos of various stages were exposed to different concentrations of lead nitrate. ß2m gene expression exhibited a continuous increase over time. Neither HSP70 nor MT were upregulated, supporting the well known sensitivity of these organisms to environmental pollutants. Interestingly, the partial MT and HSP70 mRNA sequences revealed an intimate phylogenetic relationship with these proteins in siluriforms. These partial sequences were more closely related to salmoniform proteins than to cypriniform proteins. The expression levels of HSP70 and MT were lower in embryonic tissues exposed to high concentrations of lead (500 μg/L), which impaired the fish's coping strategy via intoxication at the cellular level. In conclusion, early developmental stages appear to be particularly vulnerable to lead and fail to activate the typical coping mechanisms. Therefore, these early life stages may not be suitable to characterize concentration-dependent toxicity.
... This process continues until equilibrium point (Zhou et al.,1997).The study also revealed that HCs conc. in the blood plasma was higher under cold conditions comparing with its conc. under warm conditions because the exposure temperature affects uptake and elimination processes of HCs in case of lipid content was similar (Petersen and Kristensen , 1998). ...
To exhibit the effect of long term exposure to gas oil on ionic regulation, chloride cells (CC), total epithelial cells (EC) and histopathological alterations in gills of Liza abu (Heckel) juveniles. Several laboratory experiments were conducted under two temperatures, warm (27±2.3ºC) and cold (15±1.5ºC). Fishes were exposed to 0.5, 0.25 and 0.1 cm/l V/V of gas oil under high temperature and to 0.25, 0.1 and 0.05 cm/l under low temperature. Hydrocarbons concentrations in exposure solutions and blood plasma were measured at 5th and 14th day of treatment. A notable decline in levels of petroleum hydrocarbons in exposure solutions during both 5th and 14th days was noticed simultaneously its levels in blood plasma synchronized with those exposure solutions. A significant reduction (P< 0.01) of Na + , K + levels in blood plasma. The rise in number and percentage of chloride cells under both temperatures were also observed. It ranged under warm conditions from 5.12-3.64x10 6 cells/gm tissue compared to control treatment (1.9x 10 6 cells/gm tissue) and 5.8-4.6 x 10 6 cells/gm tissue under cold conditions. The increase in the number of chloride cells coincided with distinguished multiplication in the number of branchial epithelial cells under both selected temperatures. However, the histopathological investigations of gills in fish exposed to gas oil concentration. 0.25 and 0.5 cm/l for 14 days revealed many histological changes mainly curling, hyperplasia, fusion, and necrosis in secondary lamellae and lifting in epithelial layers along with terminal hypertrophy of the gill filament.
... Lipophilic compounds, those that are soluble in lipids or oils, can impair the organisation of lipids in a membrane and disrupt the functioning of the cell (Vesterkvist and Meriluoto, 2003 capacity of a toxin to bioaccumulate and biomagnify can be influenced by lipophilicity as lipophilic chemicals tend to accumulate in the lipids of organisms where they are retained for extended periods and more readily transfer up trophic levels (Petersen and Kristensen, 1998;Ibelings et al., 2005;Amiard and Amiard-Triquet, 2015). The wateroctanol partition coefficient (log K ow ) of MC-LR is −1 at pH 7 (Ibelings et al., 2005), suggesting that the compound is relatively hydrophilic and may not strongly interact with lipids. ...
... This process continues until equilibrium point ( Zhou et al.,1997).The study also revealed that HCs conc. in the blood plasma was higher under cold conditions comparing with its conc. under warm conditions because the exposure temperature affects uptake and elimination processes of HCs in case of lipid content was similar (Petersen and Kristensen , 1998). ...
... The blue line shows the estimated influx rate of testosterone (3.44 x 10 −6 s −1 ), based on the influx permeability of caco-2 membranes and the potential exchange surface of zebrafish larvae gills [Hilgers et al., 1990, Rombough, 1999. Figure S9: The log 10 BCF values vs. their associated log 10 K ow values for 55 chemicals measured in zebrafish embryos [El-Amrani et al., 2012, Schreiber et al., 2009, Liu et al., 2015, Stanley et al., 2009, Petersen and Kristensen, 1998, Tu et al., 2014, Hertl and Nagel, 1993, Brust, 2001. See Table S2 for exact values and references. ...
... To address this question we collected two additional BCF datasets. The first reports log 10 BCF data for 55 chemicals measured in zebrafish embryos (Additional file 1: Figure S9 and Additional file 2: Table S2) [34][35][36][37][38][39][40][41]. We used the 7C model to predict BCF data by calculating the ratio of body burden to aqueous exposure, which is moderately predictive of embryos (Fig. 4a, RMSE = 1.220) and probably due to the wide range of more hydrophobic chemicals in the dataset (Additional file 1: Figure S9). ...
Background:
A challenge of in vitro to in vivo extrapolation (IVIVE) is to predict the physical state of organisms exposed to chemicals in the environment from in vitro exposure assay data. Although toxicokinetic modeling approaches promise to bridge in vitro screening data with in vivo effects, they are often encumbered by a need for redesign or re-parameterization when applied to different tissues or chemicals.
Results:
We demonstrate a parameterization of reverse toxicokinetic (rTK) models developed for the adult zebrafish (Danio rerio) based upon particle swarm optimizations (PSO) of the chemical uptake and degradation rates that predict bioconcentration factors (BCF) for a broad range of chemicals. PSO reveals a relationship between chemical uptake and decomposition parameter values that predicts chemical-specific BCF values with moderate statistical agreement to a limited yet diverse chemical dataset, and all without a need to retrain the model to new data.
Conclusions:
The presented model requires only the octanol-water partitioning ratio to predict BCFs to a fidelity consistent with existing QSAR models. This success begs re-evaluation of the modeling assumptions; specifically, it suggests that chemical uptake into arterial blood may be limited by transport across gill membranes (diffusion) rather than by counter-current flow between gill lamellae (convection). Therefore, more detailed molecular modeling of aquatic respiration may further improve predictive accuracy of the rTK approach.
... Both zebrafish and sheepshead minnow are considered toxicologically tolerant species (Hill et al., 2005;Woltering, 1984), and though the sheepshead minnow were exposed longer than the sheepshead, both species were exposed for the same number of free swimming days (zebrafish hatched at 2dpf and the sheepshead minnow hatched at 5 dpf) which could account for the similar sensitivity to WAF exposure. Eggs tend to have a lower rate of uptake of xenobiotics than free swimming larvae due to the lower rate of transport across the chorion, decreased circulation of fluids inside the chorion, and eggs generally having a smaller surface area compared to larvae (Petersen and Kristensen, 1998). ...
The Deepwater Horizon (DWH) oil spill was the biggest in US history and released 3.19 million barrels of light crude oil into the Gulf of Mexico. In this study, we compared the toxicity of water accommodated fractions (WAFs) of naturally weathered crude oils, source oil, and source oil with dispersant mixtures and their effects on developing sheepshead minnow and zebrafish. Although a freshwater fish, zebrafish has been used as a model for marine oil spills owing to the molecular and genetic tools available and their amenability to lab care. Our study not only aimed to determine the effect of crude oil on early life stages of these two fish species, but also aimed to determine whether dissolved crude oil constituents were similar in fresh and saltwater, and if freshwater fish might be a suitable model to study marine spills. Weathering and dispersant had similar effects on WAF composition in both fresh and saltwater, except that the saltwater source oil + dispersant WAF had markedly higher PAH levels than the freshwater equivalent. WAF exposure differentially affected survival, as the LC50 values in %WAF for the zebrafish and sheepshead minnow exposures were 44.9% WAF (95% confidence interval (C.I.) 42.1-47.9) and 16.8% WAF (95% C.I. 13.7-20.5); respectively. Exposure increased heart rate of zebrafish embryos, whereas in sheepshead, source oil exposure had the opposite effect. WAF exposure altered mRNA expression of biotransformation makers, vitellogenin and neurodevelopment genes in both species. Muscle deformations were only found in oil-exposed zebrafish. This is one of the most comprehensive studies to date on crude oil toxicity, and highlights the species-specific differences in cardiotoxicity, estrogenic effects, biotransformation enzyme induction and potential neurotoxicity of crude oil exposure.
... These results highlight the difference in fish species regarding affinity of the AhR receptor to small-sized molecular compounds, with significant variations between tropical and temperate fish species (Pathiratne and Hemachandra, 2010). Environmental factors have also been demonstrated as affecting the uptake and elimination of compounds such as phenanthrene, higher in fishes in warmer temperatures compared to cold temperatures (Petersen & Kristensen, 1998). Thus, according to the literature, higher concentrations of phenanthrene and naphthalene in estuarine waters, and possibly other compounds in the sediments, may contribute to the uptake of these pollutants by the demersalbottom feeding G. genidens, inducing EROD activity. ...
The contamination of coastal areas by petroleum and its derivatives is a relevant issue based on large-scale production and consumption. This study presents field and laboratory surveys on the detoxification enzymes on the estuarine/coastal catfish Genidens genidens to understand the enzymatic responses to oil derivatives and environmental conditions. Field catalase (CAT) and glutathione S-tranferase (GST) measurements suggest oxidative stress and acting repair mechanisms in fishes, but were not induced by diesel oil as indicated by laboratory studies. On the other hand, higher ethoxyresorufin-O-deethylase (EROD) activities following higher polycyclic aromatic hydrocarbon (PAH) concentrations in the estuarine waters suggested fish responsiveness to oil contamination, mainly due to the fact that such EROD values were similar to the magnitude measured in fish during a 24-h exposure to diesel oil in the laboratory. However, other environmental estuarine conditions may also act on field EROD activities since PAHs concentrations in the water-soluble fraction of diesel oil (WSFDO) were higher than those measured in estuarine waters.
... The ability of fish embryos to bioconcentrate trace contaminants is evidenced by studies on persistent organochlorine compounds such as dioxins and PCBs. The embryos and larvae of several species were shown to accumulate PCBs at subnanomolar water concentrations to high micromolar tissue levels in a span of 3-6 days, representing several 100,000-fold bioconcentration factors (Petersen and Kristensen, 1998). ...
As a nonstop pump driven by physiologically complex excitable cells, the heart is especially susceptible to a variety of insults, in particular exogenous chemicals. In humans, for example, heart-related toxicities are the most common adverse drug reaction. Fish living in polluted environments may or may not be able to avoid exposure to cardiotoxic chemicals. Nevertheless, juvenile and adult fish have a variety of robust mechanisms for protecting the heart from toxic chemicals, such as hepatic metabolism. The situation is very different for fish early life history stages, in particular very small embryos and larvae. The developing heart is the first organ to become functional in embryos, at a point very early in its morphogenesis. Owing to the intimate and interacting links between form and function in the developing heart, very subtle cardiotoxicity during embryogenesis can cause serious and long-lasting outcomes. Fish embryos have minimal capacity for metabolic detoxification, and therefore, developmental cardiotoxicity is a real-world environmental health concern for wild populations. This chapter focuses on the exquisite sensitivity of the developing fish heart to chemical contaminants, as demonstrated through aquatic pollution case studies focused on legacy organochlorine compounds and recent oil spills. These studies have revealed a diversity of mechanisms linking cardiomyocyte physiology to heart development, and abnormal development in turn to latent impacts on physiology at later life stages.
... In addition, some authors have developed custommade zebrafish housing at low cost which could be useful to investigators with low financial support for research [44,45]. Several studies have now been conducted on zebrafish exploring the effects of various potential environmental contaminants, including methylmercury [46,47], uranium [48], cadmium [49][50][51], methylparathion [52,53] and benzopyrenes [54,55] on different structures and organs, particularly on nervous system. Heavy metals and industrial chemicals are known causes of neurodevelopmental disorders and subclinical brain dysfunction and these studies in zebrafish embryos and larvae support the hypothesis that exposure to these chemicals during early fetal development can cause brain injury at quantities lower than those affecting adult brain function. ...
Pathologies related to neurotoxicity represent an important percentage of the diseases that determine the global burden of diseases. Neurotoxicity may be related to the increasing levels of potentially neurotoxic agents that pollute the environment, which generates concern, since agents that affect children may increase the incidence of neurodevelopmental disorders, affecting the quality of life of future citizens. Many environmental contaminants have been detected, and many of them derive from several human activities, including the mining, agriculture, manufacturing, pharmaceutical, beverage and food industries. These problems are more acute in third world countries, where environmental regulations are lax or non-existent. An additional major emerging problem is drug contamination. Periodic monitoring should be performed to identify potential neurotoxic substances using biological tests capable of identifying the risk. In this sense the fish embryo test (FET), which is performed on zebrafish embryos, is a useful, reliable and economical alternative that can be implemented in developing countries.
... Considering the evidence for hydrophobicity-driven bioconcentration, a lack in steady state could be a possible reason for the diverging observations made in this study. However, Petersen and Kristensen [31] reported that steady-state concentrations were achieved for hydrophobic organic pollutants, such as naphthalene, pyrene, and benzo(a)pyrene, in zebrafish embryos after 72 h of exposure. It may be hypothesised that the observed lack in log D dependency may result from mixture effects on biological transport kinetics. ...
There is an increasing demand for analytical tools to measure the internal concentrations of xenobiotic pollutants in small organisms. Such tools are required to determine exposure in ecotoxicological studies yet avoid sophisticated clean-up and enrichment techniques or large-scale experimental design. Thus, this paper presents a modified QuEChERS method coupled to gas chromatography tandem mass spectrometry (GC–MS/MS) for small volume organic samples. Ten zebrafish (Danio rerio) embryos were exposed to a 46-compound mixture at 10 ng/mL. After 72 h of exposure, they were extracted in 200 μL glass inserts using 70 μL of both acetonitrile and water. Volumes of 50 μL of extract were injected into a GC–MS/MS with a multi-mode inlet. Internal concentrations of zebrafish embryos could be reproducibly quantified in the lower nanogram per millilitre range at detection limits of 1–25 ng/mL and with recoveries of 63–133%. Internal concentrations varied over the tested range of compounds between 5.88 ± 0.616 ng/mL for dicofol and 232 ± 18.6 ng/mL for diflufenican. Detectability and recovery were best for compounds with a log D greater than four. As internal concentrations did not seem to exclusively depend on log D, biochemical transport processes could play an important role in the uptake kinetics of early zebrafish life stages.
Oil fate and exposure modeling addresses the complexities of oil composition, weathering, partitioning in the environment, and the distributions and behaviors of aquatic biota to estimate exposure histories, i.e., oil component concentrations and environmental conditions experienced over time. Several approaches with increasing levels of complexity (i.e., aquatic toxicity model tiers, corresponding to varying purposes and applications) have been and continue to be developed to predict adverse effects resulting from these exposures. At Tiers 1 and 2, toxicity-based screening thresholds for assumed representative oil component compositions are used to inform spill response and risk evaluations, requiring limited toxicity data, analytical oil characterizations, and computer resources. Concentration-response relationships are employed in Tier 3 to quantify effects of assumed oil component mixture compositions. Oil spill modeling capabilities presently allow predictions of spatial and temporal compositional changes during exposure, which support mixture-based modeling frameworks. Such approaches rely on summed effects of components using toxic units to enable more realistic analyses (Tier 4). This review provides guidance for toxicological studies to inform the development of, provide input to, and validate Tier 4 aquatic toxicity models for assessing oil spill effects on aquatic biota. Evaluation of organisms' exposure histories using a toxic unit model reflects the current state-of the-science and provides an improved approach for quantifying effects of oil constituents on aquatic organisms. Since the mixture compositions in toxicity tests are not representative of field exposures, modelers rely on studies using single compounds to build toxicity models accounting for the additive effects of dynamic mixture exposures that occur after spills. Single compound toxicity data are needed to quantify the influence of exposure duration and modifying environmental factors (e.g., temperature, light) on observed effects for advancing use of this framework. Well-characterized whole oil bioassay data should be used to validate and refine these models.
Millions of liters of diluted bitumen (dilbit), a crude oil product from Canada's oil sands region, is transported through critical Pacific salmon habitat each day. While the toxicity of the water-soluble fraction of dilbit (WSFd) to early life-stages of salmon is known, quantitative data on life-stage differences in sensitivity to WSFd is missing. To fill this knowledge gap, we exposed two juvenile life-stages of coho salmon (O. kisutch) in parallel to very low (parts per billion), environmentally-relevant concentrations of WSFd for acute (48 h) and sub-chronic (4 wk) durations. The relative sensitivities of the two life-stages (fry and parr) were assessed by comparing the timing and magnitude of biological responses using common organismal and molecular endpoints of crude oil exposure. A significant reduction in body condition occurred in both fry and parr after 4 wk exposure to WSFd. Both life-stages also experienced a concentration-dependent decrease in time-to-loss-of-equilibrium during a hypoxia challenge test at both 48 h and 4 wk of exposure. Although organismal responses were similar, molecular responses were distinct between life-stages. In general, unexposed fry had higher baseline values of hepatic phase I biotransformation indicators than unexposed parr, but induction of EROD activity and cyp1a mRNA expression in response to WSFd exposure was greater in parr than in fry. Neither gst nor hsp70 mRNA expression, markers of phase II biotransformation and cell stress, respectively, were reliably altered by WSFd exposure in either life-stage. Taken together, results of this study do not support differential sensitivities of coho fry and parr to WSFd. All the same, the potential for ontogenic differences in the expression and induction of phase I biotransformation need to be considered because age does matter for these endpoints if they are used as bioindicators of exposure in post-spill impact assessments.
Persistent, bioaccumulative, and toxic contaminants (PBTs) are known to co-occur in fish tissue, yet this covariance has not been explicitly incorporated into model-based risk assessments that inform fish consumption advisories. We utilize available US EPA datasets to statistically model the covariance among PBT concentrations in fish tissue and the dependence of this covariance on waterbody and watershed conditions. We find that most PBTs positively covary, whether fish were collected in rivers, lakes, or coastal waters. Mercury in lakes, and mercury, PFCs, and heptachlor in rivers, covary negatively with the other PBTs. While much of the variance and covariance in PBTs can be statistically related to fish characteristics and watershed and waterbody conditions, a large amount remains in model residuals. This implies that single contaminant models, even if highly precise, can misestimate total health risk by neglecting the substantial covariance with other PBTs that is left unmodelled.
Climate change, along with environmental pollution, can act synergistically on an organism to amplify adverse effects of exposure. The Arctic is undergoing profound climatic change and an increase in human activity, resulting in a heightened risk of accidental oil spills. Embryos and larvae of polar cod (Boreogadus saida), a key Arctic forage fish species, were exposed to low levels of crude oil concurrently with a 2.3 °C increase in water temperature. Here we show synergistic adverse effects of increased temperature and crude oil exposure on early life stages documented by an increased prevalence of malformations and mortality in exposed larvae. The combined effects of these stressors were most prevalent in the first feeding larval stages despite embryonic exposure, highlighting potential long-term consequences of exposure for survival, growth, and reproduction. Our findings suggest that a warmer Arctic with greater human activity will adversely impact early life stages of this circumpolar forage fish.
Early life stages of fish are highly sensitive to crude oil exposure and thus, short term exposures during critical developmental periods could have detrimental consequences for juvenile survival. Here we administered crude oil to Atlantic haddock ( Melanogrammus aeglefinus ) in short term (3-day) exposures at two developmental time periods: before first heartbeat, from gastrulation to cardiac cone stage ( early ), and from first heartbeat to one day before hatching ( late ). A frequent sampling regime enabled us to determine immediate PAH uptake, metabolite formation and gene expression changes. In general, the embryotoxic consequences of an oil exposure were more severe in the early exposure animals. Oil droplet fouling in the highest doses resulted in severe cardiac and craniofacial abnormalities. Gene expression changes of Cytochrome 1 a,b,c and d ( cyp1a,b,c,d ), Bone morphogenetic protein 10 ( bmp10 ), ABC transporter b1 ( abcb1 ) and Rh-associated G-protein ( rhag ) were linked to PAH uptake, occurrence of metabolites of phenanthrene and developmental and functional abnormalities. We detected circulation-independent, oil-induced gene expression changes and separated phenotypes linked to proliferation, growth and disruption of formation events at early and late developmental stages. Our study gives an increased knowledge about developmentally dependent effects of crude oil toxicity. Thus, providing more knowledge and detail to new and several existing adverse outcome pathways of crude oil toxicity.
Graphical abstract
Highlights
Oil droplet fouling occurred in the whole water column and increased the oil toxicity.
Early exposure resulted in higher PAH uptake due to lower metabolism resulting in more severe abnormalities.
A rapid and circulation-indepenent regulation of bmp10 suggested a direct oil-induced effect on calcium homeostasis.
Expression of rhag indicated a direct oil-induced effect on osmoregulatory cells and osmoregulation.
Severe eye abnormalities especially in the late exposure was linked to inappropriate overexpression of cyp1b in the eyes.
The accumulation of anthropogenic chemical substances in aquatic organisms is an immensely important issue from the point of view of environmental protection. In the context of the increasing number and variety of compounds that may potentially enter the environment, there is a need for efficient and reliable solutions to assess the risks. However, the classic approach of testing with fish or other animals is not sufficient. Due to very high costs, significant time and labour intensity, as well as ethical concerns, in vivo methods need to be replaced by new laboratory-based tools. So far, many models have been developed to estimate the bioconcentration potential of chemicals. However, most of them are not sufficiently reliable and their predictions are based on limited input data, often obtained with doubtful quality. The octanol-water partition coefficient is still often used as the main laboratory tool for estimating bioconcentration. However, according to current knowledge, this method can lead to very unreliable results, both for neutral species and, above all, for ionic compounds. It is therefore essential to start using new, more advanced and credible solutions on a large scale. Over the last years, many in vitro methods have been newly developed or improved, allowing for a much more adequate estimation of the bioconcentration potential. Therefore, the aim of this work was to review the most recent laboratory methods for assessing the bioconcentration potential and to evaluate their applicability in further research.
Numerous studies of the water-soluble fraction (WSF) from crude oil have concluded that polycyclic aromatic hydrocarbons (PAHs) are the primary causative agents for early life stage (ELS) fish toxicity. Noteworthy is the lack of studies demonstrating that the sum of PAHs are capable of causing toxic effects in ELS fish at the low levels claimed (0.1-5 μg/L) without being part of a complex crude oil mixture. Crude oil and the WSF are composed of thousands of other compounds that co-occur and likely contribute to crude oil toxicity. Based on the available data, it appears that the syndrome of effects (lower heart rate, edemas, and morphological abnormalities) for ELS fish exposed to the aqueous fraction of a crude oil mixture is commonly observed in studies exposing fish embryos to high concentrations of a variety of compounds and may be a nonspecific response. We conclude that the available data support the hypothesis that this syndrome of effects is likely the result of baseline toxicity (not receptor based) due to membrane disruption and resulting alteration in ion (e.g., calcium and potassium) homeostasis. We acknowledge the possibility of some compounds in the WSF capable of causing a specific receptor based toxicity response to ELS fish; however, such compounds have not been identified nor their receptor characterized. Concluding that PAHs are the main toxic compounds for crude oil exposure is misleading and does not result in guideline values that can be useful for environmental protection. Water quality guidelines for any single chemical or suite of chemicals must be based on a complete understanding of exposure concentrations, mechanism of action, potency, and resulting response. This review focuses on the toxic effects reported for fish embryos and the purported toxic concentrations observed in the aqueous phase of an oil/water mixture, the known levels of toxicity for individual PAHs, a toxic unit approach for characterizing mixtures, and the potential molecular initiating event for ELS toxicity in fish. This review also has implications for a large number of studies exposing ELS fish to a variety of compounds at high concentrations that result in a common baseline toxic response.
Tässä katsauksessa tarkastellaan öljyn vaikutuksia kaloihin ja mahdollisen öljyonnettomuuden vaikutuksia Itämeren kalakantoihin, kalastukseen sekä vesiviljelyyn, jotta voitaisiin nykyistä paremmin valmistautua mahdollisen öljyonnettomuuden lyhyt- ja pitkäaikaisten vaikutusten arviointiin. Itämeri on häiriöille erittäin herkkä merialue, jonka luontoa jatkuvasti kasvava laivaliikenne ja erityisesti öljynkuljetukset uhkaavat. Mittava öljyonnettomuus alueella voisi aiheuttaa vakavia seurauksia luonnolle yleensä ja tapauskohtaisesti luonnonvaroille sekä rannikkovaltioiden kalataloudelle. Vedessä öljy leviää, hajoaa, haihtuu tai se voi muodostaa veden kanssa kestävän seoksen eli emulsion. Öljyn käyttäytymiseen vaikuttavat monet tekijät, kuten öljyn fysikaaliset ja kemialliset ominaisuudet, vuodenaika, sää- ja meriolot sekä öljyonnettomuuspaikka. Suomenlahdella kuljetetaan raakaöljyä, kevyitä ja raskaita öljytuotteita ja kaikissa laivoissa on polttoöljyä. Alkuperästä riippuen raakaöljyn koostumus ja ominaisuudet vaihtelevat suuresti. Raakaöljy koostuu hiilivetyjen seoksista, kuten alkaaneista ja aromaattisista hiilivedyistä. Raakaöljystä jalostetaan kevyitä öljytuotteita, kuten bensiiniä ja dieseliä. Jalostusprosessin jäännösöljyä kutsutaan raskaaksi polttoöljyksi. Öljy-yhdisteillä on sekä akuutteja että subletaaleja vaikutuksia kaloihin. Öljyn sisältämillä polyaromaattisilla hiilivedyillä (PAH) on mutageenisiä ja karsinogeenisia sekä haitallisia fysiologisia (immunologisia, endokriinisia ja osmoregulatiivisia) vaikutuksia. Kalojen varhaiset kehitysvaiheet ovat erityisen herkkiä öljy-yhdisteiden vaikutuksille. Aikuisilla kaloilla PAH-yhdisteet vaikuttavat aineenvaihduntaan, kasvuun ja lisääntymiseen. Altistuminen PAH-yhdisteille voi johtaa kalakantojen koon muutoksiin ja sitä kautta vaikuttaa koko Itämeren eliöyhteisöön. Kalastajille ja vesiviljelijöille voi aiheutua taloudellisia tappioita merellä tapahtuvan öljyonnettomuuden seurauksena mm. kalojen tahriintumisesta sekä maku- ja hajuvirheistä ja kalojen vähenemisestä sekä ammatinharjoittamisen vaikeutumisesta tai estymisestä. Ennaltaehkäisy on varmin ja halvin keino estää suuren öljyonnettomuuden aiheuttamat vakavat seuraukset. Öljynkuljetusten ja meriliikenteen turvallisuutta on pyritty lisäämään erilaisten valvontajärjestelmien ja sopimusten, kuten alusten liikennejärjestelmän ja eri alueilla toimivien alusten pakollisen ilmoittautumisjärjestelmien, avulla sekä alusten rakennemuutoksilla, kuten kaksoispohjilla. Jotta öljyonnettomuuden vaikutuksia kaloihin ja kalakantoihin sekä palautumista onnettomuudesta pystytään arvioimaan, tarvitaan monipuolista biologista tietoa perustilanteesta.
Triolein-water partition coefficients (K(tw)) have been determined for 38 slightly water-soluble organic compounds, and their magnitudes have been compared with the corresponding octanol-water partition coefficients (K(ow)). In the absence of major solvent-solute interaction effects in the organic solvent phase, the conventional treatment (based on Raoult's law) predicts sharply lower partition coefficients for most of the solutes in triolein because of its considerably higher molecular weight, whereas the Flory-Huggins treatment predicts higher partition coefficients with triolein. The data are in much better agreement with the Flory-Huggins model. As expected from the similarity in the partition coefficients, the water solubility (which was previously found to be the major determinant of the K(ow)) is also the major determinent for the K(tw). When the published BCF fvalues (bioconcentration factors) or organic compounds in fish are based on the lipid content rather than on total mass, they are approximately equal to the K(tw), which suggests at least near equilibrium for solute partitioning between water and fish lipid. The close correlation between K(tw) and K(ow) suggests that K(ow) is also a good predictor for lipid-water partition coefficients and bioconcentration factors.
The uptake, depuration, metabolic fate and bioaccumulation of two polycyclic aromatic hydrocarbons (PAH), [14C]naphthalene (NPH) and [14C]benzo()pyrene (BaP), by bluegill sunfish were determined in the presence and absence of dissolved humic material (DHM) (20 mg C/L) The effect of binding to DHM on the bioavailability of PAH was analyzed by multicompartment kinetic models to determine the relative rates of uptake of PAH dissolved in water versus that bound to DHM. DHM reduced the accumulation of BaP by 90% (97% of BaP bound to DHM) but had little effect on uptake of NPH (2% bound to DHM). The rate coefficients for uptake of bound PAH were only 0 to 10% of the uptake of dissolved PAH. The potential for biotransformation has an important role in bioaccumulation by fish. Although accumulation of total radioactivity (PAH and metabolites) is 10-fold greater in fish exposed to BaP than in fish exposed to NPH, BaP is extensively metabolized whereas NPH is not. Consequently, the bioconcentration of the parent NPH greatly exceeds that of the parent BaP. Because more hydrophobic PAH, such as BaP, have a high affinity for binding to DHM and rapid rates of biotransformation, these interactions may act to mitigate the biological impact of those very hydrophobic PAH having the greatest potential for bioaccumulation and transfer to humans via food chains.
Variation in cod stock strength in the Baltic Sea is considered to be dependent on abiotic conditions such as salinity and water oxygen content in the spawning areas (the Baltic deep basins). Spawning cod were caught off northern Gotland, Sweden, from April to June in 1989 and 1990. Our investigation revealed a reduction in spermatozoan motility and a subsequent reduction in the percentage of fertilized eggs in salinities of 10 to 12. Normal egg development required a minimum salinity of 11. This coincides with the osmolality of the seminal plasma and egg yolk; i.e., the Baltic cod is adapted to hyperosmotic conditions for spawning and is thus totally dependent on periodical inflows of saline water from the North Sea.
Among biotransformation reactions the oxidation reactions and induction and inhibition of these reactions are the most studied. Many organic (aromatic) compounds can be oxidized in fish by the cytochrome P-450 dependent monooxygenases. Enzymes catalyzing these reactions can be induced under environmental conditions either by “natural” or by anthropogenic compounds.
Monooxygenase activities vary up to 600-fold within the fishes and average activities are about 3–36% of average mammalian activities. In general conjugating enzyme activities of fish are also lower than in mammals. Activities of these conjugating enzymes can vary enormously and are very dependent on the substrates which have been used to measure these activities. If compared to oxidation reactions, much less is known about the two other types of phase I reactions: reduction and hydrolytic reactions. Of the phase II reactions the most extensively studied reactions are glucuronide, glutathione and sulphate conjugation.
Biotransformation reactions are most abundantly studied in the liver. In general liver has highest activities per gram tissue and xenobiotics will be predominantly biotransformed there, since xenobiotics pass this organ after entering the organism. Other organs, however have high metabolic activities based on these whole organs, and thus can contribute significantly to metabolism of xenobiotic compounds.
Metabolism can be influenced by several factors, such as route of administration, diet, temperature and/or season, hormones, age, sex, species and strain. The importance of these factors on biotransformation however, is still unclear.
Compounds which are metabolized relatively fast are those which can undergo conjugation, e.g. compounds with functional groups such as —COOH, —OH and/or —NH2.
The most extensively studied compounds in metabolism studies in fish are aldrin, benzo(a)pyrene, carbaryl, chlorophenols, DDT and structurally related compounds, naphthalene, parathion, phenols and some PCBs.
It may be clear from the data presented here, that fish are able to metabolize a number of xenobiotic compounds and that biotransformation can influence bioaccumulation or detoxifying or activating processes significantly. Hitherto, however only a limited number of degradation pathways have been elucidated, while very little is known about the bioaccumulation and toxicology of the metabolites which are formed. Hence a lot of research is required to increase the understanding of the role which metabolism plays in the bioaccumulation and toxicity of organic compounds and their biotransformation products.
Description
This volume represents essentially all the basic and applied aspects of aquatic toxicology. Addresses such subjects as: biological monitoring; toxicology methods development; bioconcentration; water quality management; effluent testing; physiology and behavior; and single toxicant effects.
This chapter describes the general anatomy of the gills in fish. The gills form a highly characteristic feature of fishes and their presence has a marked effect on the anatomy and functioning of the rest of the animal. A gill septum separates two adjacent gill pouches and a series of filaments is attached to its surface. In the most primitive groups, the septum forms a complete partition between the pharynx and the outer body wall. Its extension forms a flap-valve for the next posterior slit. In more advanced groups, there is a progressive reduction in the septum and the consequent freeing of the filaments at their tips. Filaments form the most distinctive respiratory structure of fish gills and are sometimes referred to as “primary lamellae.” In adult fish, the number of filaments does not increase so markedly as during the juvenile growth period, but there is a very significant increase in the length of each of them as the fish grows. The lamellae are the most important units of the gill system from the point of view of gas exchange. The rest of the basic anatomy is directed to providing a suitable support for these structures and to enable the water and blood to come into close proximity.
Lipid decomposition studies in frozen fish have led to the development of a simple and rapid method for the extraction and purification of lipids from biological materials. The entire procedure can be carried out in approximately 10 minutes; it is efficient, reproducible, and free from deleterious manipulations. The wet tissue is homogenized with a mixture of chloroform and methanol in such proportions that a miscible system is formed with the water in the tissue. Dilution with chloroform and water separates the homogenate into two layers, the chloroform layer containing all the lipids and the methanolic layer containing all the non-lipids. A purified lipid extract is obtained merely by isolating the chloroform layer. The method has been applied to fish muscle and may easily be adapted to use with other tissues.
In spite of their hydrophobicity, not all polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners accumulate significantly in fish or other aquatic organisms. This is found both in laboratory experiments and in organisms that are sampled in the natural environment. Hitherto, this congener-specific accumulation could not adequately be explained or predicted. Many PCDDs and PCDFs with four or more chlorine atoms, such as octachlorodibenzo-p-dioxin, are taken up very slowly, if at all, during aqueous exposure. Furthermore, the uptake rates after dietary exposure of these congeners are significantly less than those of other chlorinated aromatic hydrocarbons with comparable hydrophobicity, such as polychlorinated benzenes and biphenyls. A lack or a low rate of membrane permeation may help to explain this phenomenon. For several higher chlorinated congeners and for most of the lower chlorinated dioxins and furans, the rates of uptake after dietary and aqueous exposure are comparable to those of other hydrophobic aromatic hydrocarbons. The relatively low bioconcentration and biomagnification factors of these lower chlorinated PCDDs and PCDFs should thus be explained by high rates of excretion, probably by biotransformation. In several studies, polar metabolites have been identified. Furthermore, in fish in which the cytochrome P-450 system was inhibited with piperonylbutoxide, the bioconcentration factor of 2,8-dichlorodibenzo-p-dioxin was significantly higher than that in fish which were not pretreated with the blocking agent. These results support the hypothesis that biotransformation is of paramount importance for the bioaccumulation of several PCDDs and PCDFs.
A method of estimating the bioconcentration factor of organic chemicals in fathead minnows (Pimephales promelas) is described. Water at 25°C was intermittently dosed with the chemical at a nontoxic concentration in a flow-through aquarium. Thirty minnows are placed in the aquarium, and composite samples of five fish are removed for analysis after 2, 4, 8, 16, 24, and 32 d of exposure. The bioconcentration process is summarized by using the first-order uptake model, and the steady-state bioconcentration factor is calculated from the 32-d exposure. A structure-activity correlation between the bioconcentration factor (BCF) and the n-octanol/water partition coefficient (P) of individual chemicals is summarized by the equation log BCF = 0.85 log P - 0.70, which permits the estimation of the bioconcentration factor of chemicals to within 60% before laboratory testing. The facilities and resources for testing need be used only for those chemicals that are likely to result in substantial bioconcentration in organisms. The bioconcentration factors derived from tests of mixtures of chemicals are shown to be the same as those derived from tests with the chemicals individually.
Relationships between the environmentally relevant physical chemical properties of the polychlorinated biphenyls, namely, aqueous solubility, vapor pressure, Henry's law constant, and octanol–water partition coefficient are discussed. Reported experimental data are tabulated and critically reviewed. Recommended values are given for 42 of the 209 congeners; however, procedures are suggested for estimating the properties of the other congeners. Properties of mixtures are not treated. © 1986, American Institute of Physics for the National Institute of Standards and Technology. All rights reserved.
The influence of increasing molecular size and hydrophobicity on bioaccumulation kinetics in guppies (Poecilia reticulata) was investigated for a series of polychlorinated biphenyls (PCBs) in comparison with other halogenated aromatic compounds.Extremely low clearance rates were characteristic of the higher chlorinated biphenyls and resulted in a linear accumulation in fish. For these compounds, in contrast to more soluble chemicals, direct uptake from water appeared to be less efficient than uptake from contaminated food. Hexabromobenzene, octachlorodibenzo‐p‐dioxin and tetradecachloroterphenyl were not accumulated by living fish. The importance of food‐chain accumulation (biomagnification) versus direct bio‐concentration is discussed in relation to molecular structure and physico‐chemical properties of organic chemicals.
The biological potency (relative to 2,3,7,8,-tetrachlorodibenzo-p-dioxin, TCDD) of planar polychlorinated aromatic hydrocarbons (PCHs) in extracts of eggs and flesh from spawning female chinook salmon (Oncorhynchus tschawytscha) from Lake Michigan was determined by measuring the induction of 7-ethoxyresorufin O-deethylase activity in H-4-II-E rat hepatoma cells. TCDD-equivalents in flesh and egg samples ranged from 0 to 115.8pg/g, and were approximately 5-fold greater in eggs than in flesh. These results suggest that the maternal transfer of PCHs may play a role in determining the reproductive success of Lake Michigan chinook salmon.
Bioaccumulation kinetics of five di-, tri- and tetrachlorobiphenyls from water and food were studied in laboratory experiments with goldfish (Carassius auratus). First order rate constants for uptake from water and clearance were determined after simultaneous administration of the five compounds in constant concentration, and were related to bioconcentration factors obtained in a static fish-water equilibration system. Biomagnification by retention of the PCB's from food was studied in a separate experiment.The difference in clearance rates for the chlorobiphenyls is the main reason for the different bioconcentration and biomagnification factors.Absorption efficiencies from water and food are higher than 40%. Clearance half lives vary from 10 days for 2,5-dichlorobiphenyl to 60 days for 2,3′,4′5-tetrachlorobiphenyl, which is correlalated with the decreasing aqueous solubilities of the compounds. Bioconcentration factors are between 0.4 × 106 and 1.5 × 106, biomagnification factors between 0.2 and 1.7, based on extractable lipids. Substitution of chlorine in the position para to the phenyl-phenyl bond influences hydrophobicity and bioaccumulation of the PCB's more strongly than substitution in ortho position.A kinetic model is developed which accounts for the influence of the lipid content of the fish on the clearance rate of a chemical. Reproducible determination of the bioconcentration potential of environmental chemicals is possible by use of an “internal bioaccumulation standard” in a kinetic test system. Food chain accumulation in fish is likely to be an important process only for persistent chemicals with extremely low water solubility.
Reversed-phase thin-layer chromatography with methanol-water as eluent was used to study relationships between retention and hydrophobicity of non-polar aromatic compounds. For polynuclear aromatic hydrocarbons, n-alkyl- and chloro-substituted benzenes, good correlation was observed between Rm values and log Poctanol. Significantly different correlations were obtained for polychlorinated biphenyls (PCBs) containing chlorine atoms in the positions ortho to the phenyl-phenyl bond. This effect could not be explained by the measured lower πoctanol values for ortho chlorine in PCBs. Estimation of hydrophobicity from aqueous solubility, S, combined with melting point data is restricted to S values higher than 1 μg/l. A group-contribution approach, including a retention index scale, will be very useful for correlation and prediction of reversed-phase retention, hydrophobicity and environmental and toxicological properties of chemicals.
The water solubilities of several polynuclear aromatic and heteroaromatic hydrocarbons have been compiled and reviewed for consistency through correlations with parameters such as surface area, molecular volume, and boiling point. The carbocycles and oxygen and sulfur heterocycles were governed by the same correlative equations, thereby indicating that these heteroatoms entered into only a limited degree of hydrogen bonding. Equations representing the nitrogen heterocycles differed from their carbocyclic counterparts by an approximately constant amount, suggesting that while the solubilizing effect of the nitrogen heteroatom may be large, it tends to remain constant within a similar series of compounds.
To investigate relationships between the concentrations of lipophilic organochlorine compounds in salmonine fish and their eggs and the role of lipids in maternal transfer of these compounds, muscle tissue and fertilized eggs from chinook salmon (Oncorhynchus tshawytscha) and lake trout (Salvelinus namaycush) were analyzed using gas chromatography. The concentrations of organochlorine compounds in the muscle tissue of the gravid fish were significantly correlated with the concentration of these compounds in the eggs (P < 0.01). Egg lipid concentrations were species specific, poorly correlated with muscle tissue lipid concentration, and did not appear to influence organochlorine compound transfer to the eggs. Total concentrations of PCBs and p,p′-DDE concentrations in chinook salmon eggs and total concentrations of PCBs, p,p′-DDE, and dieldrin in lake trout eggs were significantly correlated with the concentrations of these compounds in the muscle tissue of the gravid fish. Consequently, spatial differences or temporal changes in the concentrations of lipophilic compounds in chinook salmon or lake trout may significantly influence the concentrations of these compounds in their eggs.
1.1. Fatty acid and lipid class composition were determined in larvae of four marine species: Atlantic halibut (Hippoglossus hippoglossus L.), plaice (Pleuronectes platessa), cod (Gadus morhua) and turbot (Scophthalmus maximus) at hatching and prior to first feeding.2.2. Total fatty acid content decreased in the four species with up to 50% reduction in one of the halibut groups. Docosahexanaoic acid (22:6 n-3) was especially utilized.3.3. Low lipid utilization was found in turbot in relation to the other three species.4.4. Water environmental temperature may explain some of the differences in the fatty acid utilization and the source of metabolic energy between cold water species (halibut, cod, and plaice) and temperate species (turbot), in the period from hatching to prior to first feeding.5.5. Relative amounts of neutral lipids and phospholipids were similar in plaice, cod and halibut, approximately 25% and 75% of total lipids, respectively, and were approximately constant during the yolk-sac stage. Neutral lipids were dominant for turbot at hatching, accounting for 53–55% of the total lipids, while phospholipids predominated prior to first feeding, being 56–59%.6.6. Phosphatidylcholine was catabolized in halibut, plaice and cod but not in turbot, while phosphatidylethanolamine tended to be synthesized in all four species.
Experimental data are presented on the enhanced apparent solubilities of naphthalene, phenanthrene, and pyrene resulting from solubilization in aqueous solutions of four commercial, nonionic surfactants: an alkyl polyoxyethylene (POE) type, two octylphenol POE types, and a nonylphenol POE type. Apparent solubilities of the polycyclic aromatic hydrocarbon (PAH) compounds in surfactant solutions were determined by radiolabeled techniques. Solubilization of each PAH compound commenced at the surfactant critical micelle concentration and was proportional to the concentration of surfactant in micelle form. The partitioning of organic compounds between surfactant micelles and aqueous solution is characterized by a mole fraction micelle-phase/aqueous-phase partition coefficient, K{sub m}. Values of log K{sub m} for PAH compounds in surfactant solutions of this study range from 4.57 to 6.53. Log K{sub m} appears to be a linear function of log K{sub ow} for a given surfactant solution. A knowledge of partitioning in aqueous surfactant systems is a prerequisite to understanding mechanisms affecting the behavior of hydrophobic organic compounds in soil-water systems in which surfactants play a role in contaminant remediation or facilitated transport.
Biuconcentration factors (BCFs) of 19 parent and hetero polycyclic aromatic obtained from static bioconcentration experiments with he&z retiadata by the initial aqueous concentration. The BCFs were obtained by fitti on~mpa~ent first-order kinetic model. The BCFs thus obtained ship with the experimental rr-octanol/water partition coefficient, log lu, (r = 0.91. s = 0. son with a lited number of semi-static tests, it was concluded that the statk biosoneen is a satisfactory alternative for more laborious bioconcentration tests to obtain BCFs o However, the static tests are less valuable for the acquisition of kinetic bioconcentratiou as, e.g., uptake or elimination rate constants. For several uf the #rn~~~ds in this stu resSting from the static tests did not match with those from a limited number of lotion ex carried out in this study or with values expected from the relationship between the depumtion tute eon-stant and the log K, reported in the literature. The distribution of three parent PAH witbin the 6sh after a 7day semi-static exposure was also investigated. Relativeiy high ~n~~tio~ were found in liver and kidneys. The major part of the body burden was found in muscle and the gas&o-intestinal tract. One of the adverse effects of the profuse use of fossil fuels by man is the nowadays ubiquitous presence of polycyclie aromatic hydrocarbons (PAW) in the environment in relatively high concentrations. There is no indication that the input into the envi-ronment as a result af human ~ti~ties will decrease subs~n~a~y in the next decades. An estimated total input of 230,MM metric tons of PAH is released allay to the aquatic environmetlt from spillage and seepage of fossil fuels, domestic and industrial *fre%#t uc;ld@~: J.C, Klaruer_ ~j~wa~~~t, T&I Waters Division, PD. Box 207% 9750 AE %re& Netherknds
The lethal body burden (LBB), the whole-body concentration in millimoles per kilogram at time of death or immobilization, and the LC50 of dihalogenated (F, Cl, Br) benzenes were measured. Except for 1,4-difluorobenzene in guppy (28 mmol kg−1), LBBs varied between 2 and 8 mmol kg−1. The LBBs of the chemicals in guppies were not significantly different from those in fathead minnows. LC50 values varied between 0.54 and 41 μmol L−1 and were inversely related to the octanol/water partition coefficient, Kow. To estimate the risk of a compound to fish, the LBB requires the exposure concentration in combination with a first-order one-compartment bioaccumulation model. Therefore, the time of death or the time of immobility, and bioconcentration parameters such as the uptake rate constant (k1) and the elimination rate constant (k2), were determined. For both species, k1 values of the chlorinated benzenes were smaller than those of the brominated compounds and k2 values decreased with increasing hydrophobicity. The lipid-normalized bioaccumulation factors (KL's) were linearly related to Kow.
Bioconcentration data are reported for a series of superhydrophobic chemicals including polybrominated biphenyls, brominated benzenes, mirex and polychlorinated biphenyls in the guppy (Poecilia reticulata). The observed bioconcentration factors follow a linear relationship with the 1-octanol/water partition coefficient for chemicals with a log Kow of up to 6. For chemicals with higher Kow values, the bioconcentration factors were lower than expected from the linear relationship. This loss of linear correlation is shown to be caused by (a) a low fraction of bioavailable chemical in the water, (b) elimination of chemical into the feces, (c) an insufficient exposure time to achieve equilibrium and (d) fish growth. Procedures are presented by which the magnitudes and relative contributions of these factors to reducing the apparent bioconcentration factor from linearity can be determined.
In spite of their hydrophobicity, not all polychlorinated dibenzo‐ p ‐dioxin (PCDD) and dibenzofuran (PCDF) congeners accumulate significantly in fish or other aquatic organisms. This is found both in laboratory experiments and in organisms that are sampled in the natural environment. Hitherto, this congener‐specific accumulation could not adequately be explained or predicted.
Many PCDDs and PCDFs with four or more chlorine atoms, such as octachlorodibenzo‐ p ‐dioxin, are taken up very slowly, if at all, during aqueous exposure. Furthermore, the uptake rates after dietary exposure of these congeners are significantly less than those of other chlorinated aromatic hydrocarbons with comparable hydrophobicity, such as polychlorinated benzenes and biphenyls. A lack or a low rate of membrane permeation may help to explain this phenomenon.
For several higher chlorinated congeners and for most of the lower chlorinated dioxins and furans, the rates of uptake after dietary and aqueous exposure are comparable to those of other hydrophobic aromatic hydrocarbons. The relatively low bioconcentration and biomagnification factors of these lower chlorinated PCDDs and PCDFs should thus be explained by high rates of excretion, probably by biotransformation. In several studies, polar metabolites have been identified. Furthermore, in fish in which the cytochrome P‐450 system was inhibited with piperonylbutoxide, the bioconcentration factor of 2,8‐dichlorodibenzo‐ p ‐dioxin was significantly higher than that in fish which were not pretreated with the blocking agent. These results support the hypothesis that biotransformation is of paramount importance for the bioaccumulation of several PCDDs and PCDFs.
The aim of the study was to examine the effects of introduced bacteria and nonionic surfactants on the degradation of polycyclic aromatic hydrocarbons (PAHs) in soil. Mineralization experiments were conducted with freshly added [14C]phenanthrene or [14C]pyrene, whereas other experiments focused on the degradation of selected PAHs present in a coal tar-contaminated soil. Inoculation of soil samples with phenanthrene-utilizing bacteria stimulated the mineralization of [14C]phenanthrene. This effect, however, was most notable in soil with a low indigenous potential for PAH degradation, and a large inoculum was apparently required to establish phenanthrene mineralization in the soil. Addition of alcohol ethoxylate and glycoside surfactants to soil samples enhanced the mineralization of [14C]phenanthrene and [14C]pyrene. The nonionic surfactants also enhanced the degradation of contaminant PAHs that were present in the soil coal tar. As an example, pyrene, benzo[b,j,k]fluoranthene, and benzo[a]pyrene were resistant to degradation in the absence of surfactants, whereas significant degradation of these PAHs was observed when surfactants were added. The surfactant-related enhancement of the degradation of PAH contaminants was less convincing when a rapidly degradable glycoside surfactant was used. This suggests that surfactants that are mineralized at moderate rates may be more applicable for increasing the availability of PAHs in soil.
Using a flow-through biotest exposure system, cod eggs, larvae and juveniles were exposed to the water-soluble fraction (WSF) of North Sea (Statfjord B) crude oil at concentrations ranging from 40–300 μg l−1 (ppb) for 1–6 weeks. The WSF was analysed by GC/MS, and was shown to be dominated by low-aromatic compounds such as benzenes, toluene and xylenes (80–90%). Cytochrome P450IA1 levels were measured by immunochemical techniques in 10 000 × g supernatants of whole larvae or juvenile gill homogenates, and in juvenile liver microsomal fractions. With rabbit anti-cod P450IA1 IgG as primary antibody in an indirect ELISA, a clear induction response was observed in the exposed groups of both larvae and juveniles. The response was dose-dependent, and recovery in clean sea-water resulted in normalization of the induced P450IA1 levels. In larvae exposed during the egg stage, the induction process seemed restricted until the time of hatching. In juvenile cod, the response was observed in the gill in addition to the liver. The study demonstrates the usefulness of the cytochrome P450IA1 ELISA in detecting sublethal biological effects of pollutants in small sample sizes where enzyme activity is difficult to measure.
The accumulation of organic residues in fish is the result of competing rates of uptake and elimination, which can be modeled by pharmacokinetic techniques. Although first-order kinetics are usually assumed, they are rarely verified. Models with biphasic, second-order or Michaelis-Menten kinetics may prove to be better choices, depending on exposure level and mode of elimination. The well-known correlation between bioconcentration factor and partition coefficient (P) derives from separate correlations for the uptake and elimination rate constants with P. While such correlations appear to be linear in the range of log P = 2–5 for organics that are not metabolized, they sometimes fail at higher values of log P. A drug transport model is proposed to account for the “non-ideal” bioconcentration of a variety of organics in fish. According to this model, uptake is a nonlinear function of partition coefficient, water solubility and membrane permeability.
A model is presented for the bioconcentration in fish of nonpolar hydrophobic chemicals that are not metabolized. The model assumes that diffusion rates through membrane-diffusion layer barriers influence uptake and depuration kinetics in fish. For extremely hydrophobic (log Kd, oct > 3 to 4) chemicals, uptake rate constants in fish are independent of the solute's hydrophobicity, whereas for low to moderately hydrophobic chemicals proportionality between these parameters is observed. Additionally, elimination rate constants for low to moderately hydrophobic chemicals are independent of the solute's hydrophobicity. In contrast, the elimination rate constants for extremely hydrophobic chemicals, such as polychlorobenzenes and -naphthalenes, are inversely proportional to hydrophobicity. In the model presented, this is due to the rates of release from the lipid compartments of the fish. The general relationships between bioconcentration kinetic parameters and hydrophobicity are in agreement with experimental data.
Changes in the lipid class and fatty acid composition of developing eggs and unfed larvae of cod (Gadus morhua L.) were studied with the objective of determining probable requirements of cod larvae for dietary lipid. The eggs were collected on 24 March 1985 from holding tanks containing cod which had been caught off the northwest coast of Scotland. Phosphatidylcholine (PC) was the only lipid class to decline in absolute terms during embryogenesis. Catabolism of neutral lipid was initiated during the first week after hatching, and the rate of neutral lipid utilisation increased after the larvae had completely absorbed their yolk sacs. The quantity of triacylglycerol (TAG) remained constant during embryogenesis, but the percentage of 22:6(n-3) int TAG increased substantially during this period. It was calculated that ca. 33% of the 22:6(m-3) released during the process of PC catabolism was incorporated into TAG and sterol ester. The results suggest that PC, replete in appropriate essential fatty acids, should represent a major proportion of the lipid in artificial diets for fish and crustacean larvae.
Bluegill sunfish (Lepomis macrochirus) were exposed to [14C]benzo(a)pyrene (BaP) in a flow-through system to examine the effects of temperature and feeding regime on BaP uptake and elimination and extent of biotransformation within the fish. The rate of uptake of BaP at 23°C was twice as fast in fish fed during aqueous exposure than in those denied food; however, the rate of elimination of radioactivity was 10 times greater in the fed fish. BaP was rapidly metabolized to polar and nonpolar metabolites, although 40 to 50% of the radioactivity in the fish appears to be covalently bound to cellular constituents. The rate of conversion of BaP to polar metabolites was also accelerated by feeding. Because animals in nature usually have food available, care must be exercised in using, applying, and extrapolating results of laboratory experiments in which food is withheld. Temperature is an environmental variable that had a significant effect on the uptake, elimination, and metabolic fate of organic contaminants. Both BaP uptake (5.8-fold) and 14C elimination rates (3.6-fold) at 13°C were lower than in fed fish exposed at 23°C. The metabolite profiles indicate that biotransformation of BaP is also much slower at the colder temperature.
To compare the susceptibility of early life stages (ELS) of rainbow trout (Salmo gairdneri), acute toxicity studies were carried out with cadmium, maneb, pentachlorophenol, 1,2,4,5-tetrachlorobenzene, parathion and dieldrin. The tests were performed with fertilized eggs before and after water hardening, early eye point eggs, late eye point eggs, sac fry and early fry. In all cases the early fry stage appeared the most critical period. Additionally, short-term static bioaccumulation experiments were performed with [14C]dieldrin. A kinetic model was developed for the static accumulation studies. The bioconcentration factor increased during embryonic development, reached a maximum at the sac fry stage and fell off again at the early fry stage. The uptake rate constant clearly increased once the egg membrane had disappeared and reached its maximum at the early fry stage. The clearance rate constant sharply increased at the early fry stage. Dieldrin was recovered almost completely from the yolk, which acted as a temporary ‘toxicant sink’. Changes in the susceptibility of ELS of S. gairdneri to pollutants are explained by metabolic modifications during embryolarval development and only partly by differences in the accessibility of the toxicants.In conclusion it is stated that in view of the lack of fish toxicity data, short-term exposure of early fry is a practical approximation in establishing toxicant concentrations acceptable for fish. For compounds having a high bioaccumulative potential the exposure period should also include the sac fry stage.
Fertilized eggs, yolk sac larvae, and juveniles of zebrafish were exposed to 14C-lindane and 14C-atrazine under static conditions and the uptake was studied for a period of 48 hours. After 24 hours, a number of animals were transferred into pesticide-free running water and the elimination was examined for another 24 hours. The bioconcentration factors (BCFs) as well as the rate constants for uptake and elimination were calculated.Except for the lindane uptake by eggs and the atrazine uptake by juveniles, the steady state was reached within five hours. For all tested developmental stages the bioconcentration factor of lindane distinctly exceeded 100, whereas it was less than 10 in case of atrazine. More than 90 % of the lindane content at steady state was eliminated within 24 hours, but only 70 to 85 % of the incorporated atrazine. However, comparable amounts remained when related to body weight: approximately 2.3 μmol atrazine/kg and 3.4 μmol lindane/kg. Juvenile zebrafish metabolized 50 % of the lindane and 4 % of the atrazine within 40 hours. Two groups of metabolites were seperated from the exposure medium: the ether- and the non-ether-extractable compounds. The metabolites were isolated by HPLC. 9 and 3 metabolites were detected for lindane, and 1 and 3 metabolites were detected for atrazine in the ether-soluble fraction and the water-soluble fraction, respectively.
Bioconcentration factors (BCFs) of 19 parent and hetero polycyclic aromatic hydrocarbons (PAH) were obtained from static bioconcentration experiments with Poecilia reticulata by monitoring the decrease in the initial aqueous concentration. The BCFs were obtained by fitting the observed concentrations to a one-compartment first-order kinetic model. The BCFs thus obtained showed a satisfactory linear relationship with the experimental n-octanol/water partition coefficient, log Kow (r = 0.91, s = 0.30). By comparison with a limited number of semi-static tests, it was concluded that the static bioconcentration experiment is a satisfactory alternative for more laborious bioconcentration tests to obtain BCFs of (hetero) PAH. However, the static tests are less valuable for the acquisition of kinetic bioconcentration parameters such as, e.g., uptake or elimination rate constants. For several of the compounds in this study, the estimates resulting from the static tests did not match with those from a limited number of depuration experiments carried out in this study or with values expected from the relationship between the depuration rate constant and the log Kow, reported in the literature. The distribution of three parent PAH within the fish after a 7-day semi-static exposure was also investigated. Relatively high concentrations were found in liver and kidneys. The major part of the body burden was found in muscle and the gastro-intestinal tract.
The physical chemical equations relating solubility to octanol water partition coefficient are presented and used to develop a new correlation between these quantities which includes a melting point (fugacity ratio) correction. The correlation is satisfactory for 45 organic compounds but it is not applicable to organic acids. When applied to very high molecular weight (> 290) compounds the correlation is less satisfactory; either it is believed because the data are inaccurate or because the tendency for these compounds to partition into organic phases is less than expected. This may have profound environmental implications.
The binding of o,p′-DDT by plasma lipoproteins and its accumulation in the gonads of Atlantic croaker (Micropogonias undulatus) were investigated. Tissue accumulation of o,p′-DDT was determined in fish fed o,p′-DDT for a 3 week period during gonadal recrudescence at concentrations of 1.8, 10.8, and 54.6 μg o,p′-DDT per 100 g fish day−1. The ovaries accumulated significantly more o,p′-DDT than the testes at the three dosage levels (P < 0.001). Furthermore, there was a positive linear correlation between the size of the ovaries, as calculated by the gonadosomatic index, and their o,p′-DDT content (r2 = 0.52, 0.85, and 0.76 for the low, middle and high doses, respectively). Compartmentalization of o,p′-DDT within the oocyte occurred, with over 95% of the o,p′-DDT present in the triglyceride-rich oil globule. The triglyceride-rich, very low density lipoprotein (VLDL) fraction of the plasma contained the highest percentage of o,p′-DDT (40%) with little (less than 7%) in the vitellogenin-containing VHDL. In addition, ovarian uptake of o,p′-DDT when it was bound to VLDL was six times greater than that observed after injection of o,p′-DDT bound to vitellogenin or in corn oil. The results suggest that o,p′-DDT is carried in the plasma via lipoproteins and that oocyte uptake of triglyceride-rich VLDL is a major mechanism of o,p′-DDT accumulation in croaker ovaries.
The physical-chemical factors influencing bioconcentration of organic solutes are examined, and it is suggested that a directly proportional relationship exists between bioconcentration factor and octanol-water partition coefficient. A one-constant correlation is derived and shown to give a satisfactory fit of the available data for fish. The correlation can be extended to give a simple relationship between bioconcentration factor and aqueous solubility.
Most algorithms for the least-squares estimation of non-linear parameters have centered about either of two approaches. On the one hand, the model may be expanded as a Taylor series and corrections to the several parameters calculated at each iteration on the assumption of local linearity. On the other hand, various modifications of the method of steepest-descent have been used. Both methods not infrequently run aground, the Taylor series method because of divergence of the successive iterates, the steepest-descent (or gradient) methods because of agonizingly slow convergence after the first few iterations. In this paper a maximum neighborhood method is developed which, in effect, performs an optimum interpolation between the Taylor series method and the gradient method, the interpolation being based upon the maximum neighborhood in which the truncated Taylor series gives an adequate representation of the nonlinear model. The results are extended to the problem of solving a set of nonlinear algebraic e
In a series of size classes of fathead minnow, bioconcentration kinetics and bioconcentration factors of five polychlorinated benzenes and biphenyls are weight related. A simple bioaccumulation model for hydrophobic chemicals in fish is presented that is based on diffusive mass transfer. The model contains physical-chemical and size-related parameters. The model calculations are in good agreement with experimental values from the literature for uptake and elimination rate constants. The model, however, partly explains the observed size and octanol/water partition coefficient (K(OW)) related uptake and elimination rate constants in the present study with juvenile fathead minnow. Physiological factors other than size-related parameters, such as uptake by skin, are suggested to be important as well. The main fish-related parameters are (gill) exchange surface area and lipid content; the main physical-chemical parameters are K(OW) and molecular weight.
No major differences between the accumulation of di- and tetra-, bromo- and chlorobiphenyls by fish are apparent. In contrast to hexachlorobenzene, hexabromobenzene is not accumulated either from water or from food.
The concentration of both chloro- and bromo-substituted compounds in water was of the same order of magnitude, and in both cases fish accumulated higher concentrations from water than from food. In both groups of compounds, the accumulation coefficients generally decreased with increasing degree of substitution during the uptake from water, and increased with increasing degree of substitution when taken up from food. Of the dihalobiphenyls, the 3,4-isomer accumulated from water much less than 2,6- and 2,4-dihalobiphenyl, and did not accumulate from food.
Partially debrominated compounds were not detectable in fish exposed either from water or from food, but a dibromobiphenylol was tentatively detected in the former. Mortality after exposure to chlorine occurred among fish fed the mixture of brominated hydrocarbons and their toxicity should be further studied.
The lipid class compositions of Atlantic herring eggs and larvae were determined immediately before fertilization, after fertilization and at various times during subsequent embryonic and early larval development. Total lipid constituted 15% of the dry wt of ripe eggs, 70% of the total lipid being polar lipid with phosphatidylcholine (PC) accounting for almost 90% of the polar lipid. In general, the total lipid content decreased gradually during embryogenesis and in particular during larval development. Within 3 hr after fertilization the relative percentage of neutral lipid decreased slightly. This was followed by a general decrease in polar lipid which, by the stage of yolk sac absorption, was reduced to 52% of the total lipid. The decreased percentage of polar lipid was due entirely to a decrease in PC, which was reduced to 66% of the polar lipids at the stage of yolk sac absorption. The accompanying increase in the percentage of neutral lipids was mainly due to increased percentages of triacylglycerols (TAG) up to yolk sac absorption and cholesterol esters in the larval stages. During the first 4 days after hatching, phospholipids and to a lesser extent cholesterol were preferentially depleted in the yolk sacs, which also had higher levels of free fatty acids. The results are discussed in relation to possible roles of different lipids during embryonic and early larval development.
1. Ripe English sole (Parophrys vetulus) force-fed [3H]benzo[a]pyrene, contained 1% of the dose in liver, 0.2% in ovary and 0.1% in testis, after 24 h. No significant change occurred in levels of radioactivity from 24 to 168 h. 2. Gonads and blood contained substantially larger proportions of unchanged benzo[a]pyrene (15-37% of tissue radioactivity) and organic solvent-soluble metabolites (6-35%) than did liver and bile. 3. T.l.c. revealed the presence of phenols, quinones, 7,8-dihydro-7, 8-dihydroxy- and 9,10-dihydro-9,10-dihydroxy-benzo[a]pyrene in liver and gonads. 4. A small proportion (less than 10%) of the radioactivity in liver and gonads was present as glucuronides and sulphates; bile contained a higher proportion (ca. 20%) of total radioactivity as glucuronides and sulphates. 5. Benzo[a]pyrene intermediates were covalently bound to liver proteins and DNA, and to a lesser extent to gonadal proteins (male and female fish) and gonadal DNA (confirmed for testis only).
Bluegills (Lepomis macrochirus Raf.) were exposed to [14C]anthracene or [14C]benzo[a]pyrene (B[a]P) in water. Rates of uptake and biotransformation within the fish were followed by 14C counting and thin-layer and liquid chromatography. The initial uptake-rate coefficient for anthracene (KU = 36 hr-1) was found to be independent of exposure concentration. The presence of dissolved humics did not affect anthracene uptake but did reduce the B[a]P uptake rate significantly. Biotransformation of the anthracene was constant at 0.22 nmol/g/hr, with approximately 92% of the residue unmetabolized at 4 hr. Uptake of B[a]P was linear (KU = 49 hr-1), although biotransformation increased from 0.044 to 0.088 nmol/g/hr between 1 and 2 hr of exposure. Only 11% of the B[a]P 14C activity at 4 hr represented the parent compound. Although 6% of the anthracene was found in liver and gall bladder, 25% of the B[a]P was distributed in the two organs. Depuration rates were first order and yielded half-lives of 17 hr for anthracene and 67 hr for B[a]P. The estimated bioconcentration factors (BCF) for anthracene and B[a]P in whole fish (KU/KD) were 900 and 4900, respectively, for total 14C activity, but only 675 and 490 for parent material. These BCFs were considerably lower than those predicted from the octanol-water partition coefficients because of biotransformation.
The developmental patterns of aryl hydrocarbon hydroxylase (AHH) activity and NADPH-cytochrome c reductase activity were followed during embryonic development in Fundulus. AHH activity was localized in microsomal fractions prepared from whole Fundulus embryos and eleutheroembryos. On the basis of this subcellular localization, the requirements of O2 and NADPH for activity, and sensitivity to carbon monoxide and cytochrome c inhibition, the AHH activity in Fundulus embryos and eleutheroembryos appeared to be cytochrome P-450 dependent. AHH activity was measurable in stages prior to the appearance of the liver rudiment, and during subsequent embryonic development the extrahepatic tissues were likely to have contributed substantially to the AHH activity measured. At all stages assayed before hatching, microsomal AHH specific activity remained uniformly low, but within 24 hr of hatching, AHH specific activity increased about ninefold. This posthatching increase in AHH activity was not age dependent, nor developmental stage dependent, but rather required hatching, and was not due to the presence of endogenous inhibitors in prehatching stages. The levels of NADPH-cytochrome c reductase activity and AHH activity were not closely correlated in whole embryo and eleutheroembryo microsomes, but the AHH activity in these preparations apparently was not limited by the levels of the NADPH-cytochrome c (P-450) reductase. The presence of AHH activity in Fundulus embryos during the period of active organogenesis, prior to hatching, indicates that this species is likely to be susceptible to a variety of teratogens requiring metabolic activation, and this may be the case for other species of fish as well.
This paper deals with the correlation between the partition coefficient and the concentration factor of alkyl benzenes in crude oil for gold fish and also the correlation between the partition coefficients and concentration factor of alkyl dibenzothiophene for shellfish reared in oil suspension. A straight line relationship was found between the partition coefficient of alkyl benzenes and their bioconcentration factor for goldfish. The results agree with the relation between the partition coefficient of chlorinated hydrocarbon and their bioconcentration factors for trout muscle as described by Neely 1974. However, there are no reports on relationship between the partition coefficient of chemicals and their bioconcentration factor for the biota caught in the sea. A straight line relationship was found between the Log partition coefficient of alkyl dibenzothiophenes and their bioconcentration in the shellfish reared in oil suspension and also in those caught in the sea. Data indicate the bioconcentration of alkyl dibenzothiophenes and their partition coefficients follow a straight line relationship not only in experimental polluted shellfish but also in naturally polluted shellfish.
English sole (gravid females and ripe males) were force-fed [3H]naphthalene (NPH) in salmon oil and tissues were examined at 24, 48, and 168 hr. NPH was detected in all tissues and fluids examined (e.g., liver, blood, muscle, bile, testes, and ovaries) at 24 hr. There were no statistically significant differences in NPH concentrations, based on dry weight, between comparable tissues and fluids of the sexes, except for the gonads. Ovarian NPH concentrations were approximately three times higher than those in testes. The highest percentage (5%) of the total dose at 24 hr was present in the ovaries; liver and muscle contained about 1–2% of the dose. Concentrations of NPH in all tissues declined markedly from 24 to 168 hr. At 24 hr, male English sole had significantly higher hepatic NPH hydroxylase activity than did female sole. However, no significant sex differences were evident in tissue concentrations of total metabolites of NPH. In liver, blood, and testes, the metabolites at 24 hr were composed of approximately equal proportions of conjugates and nonconjugates. Nonconjugates were the predominant metabolites in the ovaries (>88% of the total). Thin-layer chromatography (TLC) of metabolites from liver, blood, ovaries, and testes revealed that the major nonconjugate metabolite was 1,2-dihydro-1,2-dihydroxynaphthalene (diol) and glucuronides were the major conjugate class present. Both TLC and high-performance liquid chromatography indicated that the glucuronide conjugate in the liver was derived from the diol. The naphthol conjugates were not detected. The ability of fish to rapidly accumulate orally administered NPH and its metabolites in the gonads may have significant implications with respect to fertilization and subsequent development of the embryo.
This chapter describes the flame ionization detection (FID) applied to thin-layer chromatography (TLC) on coated quartz rods. Iatroscan combines TLC with the FID, and the TLC/FID combination extends TLC sensitivity by two or more orders of magnitude into the range achieved only with gas chromatography. A Chromarod, after development and freeing of solvent, is passed through the hydrogen flame and the carbon ions produced are collected and amplified. In the actual apparatus the housing supports a moving frame, which in the TH-10 model that accepts any number of Chromarods up to 10. The short development time of the Chromarod-S is an encouragement to the sequential use of different solvent systems. By judicious choice of solvent systems, complex separations can often be effected that are not possible with one solvent system, and others can be much improved. A complex mixture of hydrocarbon in a heavy fuel oil could be resolved on a Chromarod-S into four main fractions, which includes asphaltines and polar compounds, resins, polynuclear aromatics and alkyl aromatics, and aliphatics.
Bioconcentration experiments were performed on 28 polychlorinated biphenyl (PCB) congeners with NCl = 2 to NCl = 10, evaluating them simultaneously. Bioconcentration factors (BCFs) were calculated from the uptake rate constant (k1) and the clearance rate constant (k2) as BCF = k1/k2. BCFs on a wet weight basis ranged from 7710 to 940,000. They were correlated with octanol-water partition coefficients (P). The curvilinear relationship between log BCF and log P based upon data covering the log P range 5.06 to 8.18. About a log P of 7.38, a range of "optimal lipophilicity," results in highest BCFs for PCBs, above which the degree of bioconcentration decreases.