Atrazine in North America Surface Waters: A Probabilistic Aquatic Ecological Risk Assessment
... The large number of published cosm studies with atrazine represent a unique database for the establishment of an LoC (USEPA 2003;2007b;2009a;2012a;2016;Erickson 2012;Giddings et al. 2005; Acce pt e d Prep rint This article is protected by copyright. All rights reserved Solomon et al. 1996). ...
... These community-level studies potentially represent the most environmentally realistic investigations of the responses to atrazine exposures and therefore provide the best available ecologically relevant endpoints, consistent with the goal of protecting aquatic primary producer community structure and function. After USEPA's publication of the initial atrazine cosm database (USEPA 2003), detailed investigation revealed that some of the critical studies were unreliable and that others had been misinterpreted (Giddings et al. 2005). These conclusions were corroborated by several meetings of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP) (USEPA 2007a;2009b;2012b), but certain of the SAP's most significant recommendations were not reflected in USEPA's most recent iteration of the database (USEPA 2016). ...
... The scoring results were consistent with USEPA's (2016) for most data points. However, 14 data points were rescored from "1" to "0" for reasons presented previously (Giddings 2012;Giddings et al. 2005;Solomon et al. 1996) and affirmed by the SAP (USEPA 2009b; 2012b). Effect scores for each data point are provided in Table SI-1. ...
The U.S. Environmental Protection Agency (USEPA) has historically utilized different methods to derive an aquatic level of concern (LoC) for atrazine, though all have generally relied on an expanding set of mesocosm and microcosm (“cosm”) studies for calibration. The database of results from ecological effects studies with atrazine in cosms now includes 108 data points from 39 studies and forms the basis for assessing atrazine's potential to impact aquatic plant communities. Inclusion of the appropriate cosm studies and accurate interpretation of each data point – delineated as binary scores of “effect” (effect score 1) or “no effect” (effect score 0) of a specific atrazine exposure profile on plant communities in a single study – is critical to USEPA's approach to determining the LoC. We reviewed the atrazine cosm studies in detail and carefully interpreted their results in terms of the binary effect scores. The cosm database includes a wide range of experimental systems and study designs, some of which are more relevant to natural plant communities than others. Moreover, the studies vary in the clarity and consistency of their results. We therefore evaluated each study against objective criteria for relevance and reliability to produce a weighting score that can be applied to the effect scores when calculating the LoC. This approach is useful because studies that are more relevant and reliable have greater influence on the LoC than studies with lower weighting scores. When the current iteration of USEPA's LoC approach, referred to as the plant assemblage toxicity index (PATI), was calibrated using the weighted cosm dataset, the result was a 60‐d LoC of 21.2 µg/L. This article is protected by copyright. All rights reserved
... These chemicals linger in the environment for a very long period and keep steadily piling up. Pesticides infiltrate surface waters by runoff and erosion, according to Giddings et al. (2005). Pesticides enter aquatic animals through the skin, gills, or food contamination. ...
... Pesticides with atrazine and copper disrupt the photosystem II electron transport chain. Carbon dioxide (CO 2 ) builds up inside the plant cell as a result of this inhibition (Giddings et al., 2005). Additionally, additional ions take the place of the magnesium ion (Mg 2+ ) in the chlorophyll. ...
To promote plant development and enhance agricultural yield, farmers utilise a variety of agrochemicals. Insecticides, herbicides, fungicides, weedicides, and other pesticides are among the agrochemicals. The agrochemicals and their classification are mentioned in this chapter. The pros and cons of agrochemicals are also discussed in the report. Focus is also placed on how agrochemicals affect the ecology and how they work. Included are the risks and protective measures related to the usage of agrochemicals. These crucial agrochemical issues will be covered in full in the study. Future research into the molecular basis of agrochemical mechanisms must be done.
... Atrazine is an herbicide widely used in the United States (U.S.) to improve production of corn and sorghum crops since its first registration in 1958. Atrazine is moderately persistent under aerobic soil conditions and in aerobic aquatic conditions (Giddings et al., 2005). Mobility in soil is characterized as moderate, with the soil organic matter-normalized sorption partition coefficient (K OC ) ranging from 40 to 394 over 49 different soils (Giddings et al., 2005). ...
... Atrazine is moderately persistent under aerobic soil conditions and in aerobic aquatic conditions (Giddings et al., 2005). Mobility in soil is characterized as moderate, with the soil organic matter-normalized sorption partition coefficient (K OC ) ranging from 40 to 394 over 49 different soils (Giddings et al., 2005). Its moderate soil mobility makes it potentially susceptible to storm-induced runoff from field especially when application is made close to rain events leading to detectable pulses of exposure in headwater streams. ...
The estimation of upper percentiles of chemical concentrations in surface water systems within sites and regions may be necessary for the assessment of potential risk to ecosystems and human health. Limited sample sizes at monitoring sites often limit the use of direct methods to estimate upper percentiles. In such cases, upper percentiles within regions within a time frame may be estimated by pooling data across sites and years, and then deriving percentile estimates from the pooled dataset. The method uses the observations resulting from either a known probability‐sampling design or a sampling design treated like one because its observations come close to matching that of a probability‐sample. These observations are then weighted to ensure that estimates are representative of a target population across all the sites within the region and the range of years in the time frame. This method of estimating upper percentiles of annual site concentration profiles is demonstrated using atrazine and validated using the monitoring data from both sparsely sampled and high‐frequency water monitoring programs, where point and interval estimates of the 90th, 95th, and 99th pooled population percentiles are provided. This method shows that the pooled data from multiple sparse datasets can be used to provide estimates of near‐peak concentrations with greater certainty, which are consistent with those generated by high‐frequency sampling monitoring programs.
... In water systems, runoff and erosion are the two major routes for the entrance of pesticides into the earth surface [54]. A trophic-level increment of pesticides is possible via various routes in the environment, such as bioconcentration, ingestion, and biomagnification [55,56]. ...
... For these reasons, some of the pesticides degrade faster, and others slower [65]. Pentachlorophenol (PCP), polychlorinated biphenyl (PCBs), and trinitrotoluene (TNT) degrade slowly, whereas atrazine, 1,3-dichloropropene, pyrethroids, and methomyl degrade faster [2,3,54]. In the past, axenic cell cultures have been more focused on in pesticide degradation than microbial consortia [69]. ...
The application of microbial strains as axenic cultures has frequently been employed in a diverse range of sectors. In the natural environment, microbes exist as multispecies and perform better than monocultures. Cell signaling and communication pathways play a key role in engineering microbial consortia, because in a consortium, the microorganisms communicate via diffusible signal molecules. Mixed microbial cultures have gained little attention due to the lack of proper knowledge about their interactions with each other. Some ideas have been proposed to deal with and study various microbes when they live together as a community, for biotechnological application purposes. In natural environments, microbes can possess unique metabolic features. Therefore, microbial consortia divide the metabolic burden among strains in the group and robustly perform pesticide degradation. Synthetic microbial consortia can perform the desired functions at naturally contaminated sites. Therefore, in this article, special attention is paid to the microbial consortia and their function in the natural environment. This review comprehensively discusses the recent applications of microbial consortia in pesticide degradation and environmental bioremediation. Moreover, the future directions of synthetic consortia have been explored. The review also explores the future perspectives and new platforms for these approaches, besides highlighting the practical understanding of the scientific information behind consortia.
... Because most organisms interact with each other in the food web, knowledge about pesticide migration and bioconcentration from dietary exposure is important for the evaluation of their real environmental effects (Katagi, 2010). Runoff and erosion can be major routes of chemical entry into surface waters (Giddings et al., 2005) and so, for aquatic organisms, persistent chemicals may also accumulate through other mechanisms including via the direct uptake from water by gills or skin (bioconcentration), via uptake of suspended particles (ingestion), and via the consumption of contaminated food (biomagnification) (van der Oost et al., 2003). Terrestrial wildlife can be exposed to pesticides via consumption of contaminated food or water (Solomon et al., 2008). ...
... For example, atrazine inhibits photosynthesis via competition with plastoquinone II at its binding site and blocks electron transport in photosystem II (Devine et al., 1993). This inhibition results in the cessation of carbohydrate synthesis, leading to a subsequent reduction in the carbon pool and a buildup of CO2 within the plant cell (Giddings et al., 2005). At high concentrations, copper or copper-containing pesticides can interrupt electron transport through photosystem II. ...
Pesticides are known for their high persistence and pervasiveness in the environment, and along with products of their biotransformation, they may remain in and interact with the environment and living organisms in multiple ways, according to their nature and chemical structure, dose and targets. In this review, the classifications of pesticides based on their nature, use, physical state, pathophysiological effects, and sources are discussed. The effects of these xenobiotics on the environment, their biotransformation in terms of bioaccumulation are highlighted with special focus on the molecular mechanisms deciphered to date. Basing on targeted organisms, most pesticides are classified as herbicides, fungicides, and insecticides. Herbicides are known as growth regulators, seedling growth inhibitors, photosynthesis inhibitors, inhibitors of amino acid and lipid biosynthesis, cell membrane disrupters, and pigment biosynthesis inhibitors, whereas fungicides include inhibitors of ergosterol biosynthesis, protein biosynthesis, and mitochondrial respiration. Insecticides mainly affect nerves and muscle, growth and development, and energy production. Studying the impact of pesticides and other related chemicals is of great interest to animal and human health risk assessment processes since potentially everyone can be exposed to these compounds which may cause many diseases, including metabolic syndrome, malnutrition, atherosclerosis, inflammation, pathogen invasion, nerve injury, and susceptibility to infectious diseases. Future studies should be directed to investigate influence of long term effects of low pesticide doses and to minimize or eliminate influence of pesticides on non-target living organisms, produce more specific pesticides and using modern technologies to decrease contamination of food and other goods by pesticides.
... Blanchard's cricket frogs are declining in parts of their range, which overlaps the US Midwest, a region of intensive atrazine use [18,19]. In addition, because atrazine is primarily a pre-emergent herbicide, enters aquatic systems via runoff, and is persistent, exposure at the time of reproduction is likely [20]. Lastly, cricket frogs appear to be sensitive to the estrogenic impacts of atrazine based on the results of experimental larval exposures (T.D. Hoskins and M.D. Boone, unpublished data) and a field study that found rates of intersexuality to be weakly associated with atrazine concentrations [21]. ...
... Lastly, cricket frogs appear to be sensitive to the estrogenic impacts of atrazine based on the results of experimental larval exposures (T.D. Hoskins and M.D. Boone, unpublished data) and a field study that found rates of intersexuality to be weakly associated with atrazine concentrations [21]. In the present study, we exposed reproductively mature adults to ecologically relevant concentrations of atrazine (0, 1, or 10 mg/L; concentrations based on Giddings et al. [20]) in seminatural, outdoor breeding arenas and measured effects on the probability of breeding and on the number of tadpoles produced in a single reproductive event. We predicted that presence of atrazine would reduce both the probability of breeding and the number of tadpoles produced relative to controls. ...
Studies of endocrine-disrupting contaminants have focused on early-life exposures, but later exposures could impact fitness. We exposed adult frogs (Acris blanchardi) at reproduction to ecologically relevant atrazine concentrations (0, 1, or 10 µg/L) in outdoor arenas. We measured likelihood of breeding and number of resulting tadpoles. Atrazine did not impact probability of breeding nor tadpoles produced, suggesting anuran reproductive success may not be impacted by short-term exposure to low concentrations. This article is protected by copyright. All rights reserved.
... Presence of atrazine at the levels lower than the limit of detection in other periods could be due to the relatively low sensitivity of GC-MS (LOD: 0.01 µg/ml in water and 0.01 µg/g in sediment). However, given the fact that atrazine is relatively stable with half-life in surface water of more than 200 days (ATSDR, 2003), the levels found in this study pose potential concerns over its effect to aquatic life since it is quite close to the lowest observed effect concentration for early life stage of fish (0.46 µg/ml; Giddings et al., 2005). Since bioconcentration of atrazine is unlikely (Giddings et al., 2005), atrazine residue in mussel tissue was thus determined by ELISA in order to yields a more sensitive assay (LOD: 0.53 ng/g dry weight). ...
... However, given the fact that atrazine is relatively stable with half-life in surface water of more than 200 days (ATSDR, 2003), the levels found in this study pose potential concerns over its effect to aquatic life since it is quite close to the lowest observed effect concentration for early life stage of fish (0.46 µg/ml; Giddings et al., 2005). Since bioconcentration of atrazine is unlikely (Giddings et al., 2005), atrazine residue in mussel tissue was thus determined by ELISA in order to yields a more sensitive assay (LOD: 0.53 ng/g dry weight). Detectable levels (1.44-16.69 ...
Seasonal cultivation in northern part of Thailand leads to widely uses of agrochemicals especially atrazine herbicide. To examine whether an intensive use of atrazine could lead to contamination in aquatic environment, sediment and water were collected from an agricultural catchment in Nan Province during 2010-2011 and subjected to analysis for atrazine by GC-MS. The results showed that detectable levels of atrazine were found in water (0.16 μg/ml) and sediment (0.23 μg/g) of the catchment. To monitor potential effects of atrazine on aquatic animals, a freshwater mussel Uniandra contradens was used as a sentinel species for bioaccumulation and potential health effects. Mussels collected from the catchment during 2010- 2011 were subjected to analysis for atrazine residue in tissue and condition factor based on body weight and shell length. The results showed that detectable levels of atrazine were found in mussel tissue with the highest level (8.40 + 2.06 ng/g) in late wet season when runoff from heavy rain was evidenced. Condition factor, an indicative of overall health, showed a significant negative correlation with atrazine residue in the tissue. This information could be used as part of the monitoring program for herbicide contamination and potential health effects in agricultural environment.
... The 10th percentile toxicity for Irgarol and M1 are 193 ng/L and 5622 ng/L, respectively (Hall et al., 2009). The 10th percentile toxicity for Atrazine, derived from phytoplankton and macrophyte toxicity data, was calculated to be 3.84 μg/L for freshwater species and 7.08 μg/L for saltwater species (Giddings et al., 2005). An area is labeled at risk for toxic exposure when environmental levels exceed toxicity benchmarks, such as when the 90th percentile environmental exposure exceeds the 10th percentile plant toxicity for the analyte. ...
... Atrazine is widely used as a household herbicide, often in combination with fertilizer, to reduce the growth of grassy weeds, and also used in the treatment of sugarcane crops in Southeast Florida (Giddings et al., 2005). Therefore it seems to be rather ubiquitous in coastal areas where run-off enters nearshore waters. ...
Irgarol is a common antifoulant present in coastal environments experiencing high boating activities. Irgarol, its degradation product M1, and the similarly structured herbicide Atrazine, are highly toxic to non-target marine organisms and thus pose a continual risk to the environment. Nearshore areas with intensive boating activity were assessed for environmental exposure to Irgarol, M1, and Atrazine. Irgarol levels up to 241ng/L were measured in surface water collected at Key Largo Harbor. Irgarol's metabolite, M1, was detected at levels up to 50ng/L. Atrazine levels reached 21ng/L throughout Miami River, and were also detected in waters within Biscayne Bay Aquatic Preserve at 7±4ng/L. The Irgarol 90th percentile exposure concentration (176ng/L) in Southeast Florida - including Biscayne Bay - surface waters were found to exceed most toxicity benchmarks, suggesting Irgarol concentrations may be high enough to cause undesired effects on aquatic plants. Indigenous species of SAVs were also collected throughout Southeast Florida and assessed for their Irgarol and M1 bioaccumulation capabilities. All SAV species collected revealed Irgarol bioaccumulation capabilities and a 90th centile bioconcentration factor (BCF) of 9830. Several of those species were also capable of bioaccumulating M1, with a 90th centile BCF of 391. A 43-day in situ transplant between an impacted area and a pristine area within Biscayne Bay waters showed SAVs were able to uptake Irgarol from the environment with quick kinetics: tissue concentrations were 66 times greater than the water concentration within 6weeks. Halodule and Syringodium had the highest capacity to bioaccumulate from marina surface waters, as indicated by the Irgarol BCF (Halodule=6809, Syringodium=6681) and M1 BCF (Halodule=277, Syringodium=558). Halodule and Syringodium are therefore the best candidate species to serve as bioindicators indicators of acute Irgarol contamination.
... Atrazine (2-chloro-4-(ethylamino)-6-(isopropylamine)-S-triazine) is an herbicide commonly used in many countries to control weeds of broadleaves and grasses in intensive agricultural farms. Atrazine acts by inhibiting electron transport in Photosystem II, which disrupts the plant's ability to photosynthesize and causes starvation in broad-leaf plants and eventual death (Giddings et al 2004). It has been shown to have diverse effects on organisms such as amphibians and fish that develop and live in freshwater (Rohr 2018). ...
Pesticides from agricultural run-off pose a severe threat to non-target organisms, such as fishes. This study was carried out to evaluate acute toxicity and histological and genotoxic effects (erythrocytic nuclear abnormalities) of lethal and sub-lethal concentrations of three commonly used pesticides: Atrazine, Butachlor and Glyphosate on the African mud catfish (Clarias gariepinus). Fishes were exposed to the pesticides for 96h periods to determine their LC50 and the sub-lethal effect at various concentrations (1/10th, 1/100th , 1/1000th 96h LC50) over 28 days. The 96h LC50 values were 7.63mg/l, 0.7mg/l and 15.97mg/l for atrazine, butachlor and glyphosate, respectively. Histological sections of the liver of C. gariepinus exposed to the three pesticides showed mild vascular congestion but no necrosis in the tissue. There was a significant (p<0.5) dose-dependent increase in micronuclei and nuclear abnormalities in the erythrocytes of exposed C. gariepinus compared to the control by 28 days. The study confirmed that C. gariepinus are at risk of adverse effects from exposure to pesticides. Discharge of agricultural run-off around water bodies should be prevented or prohibited to avoid adverse effects on aquatic life.
... Understanding the impacts of atrazine exposure on non-target aquatic organisms has been the focus of many reviews (Giddings, 2005;Solomon et al., 2008;Van Der Kraak et al., 2014;de Albuquerque et al., 2020). Because atrazine comes into contact with a broad range of aquatic organisms, it can cause sublethal effects to nontarget species and interfere with the behavior, morphology and physiology of many species at environmentally relevant concentrations. ...
The herbicide atrazine is widely used for controlling broad leaf weeds and increasing crop yields in agricultural areas. Atrazine enters aquatic environments through runoff, ground water discharge and seepage where concentrations have been recorded above 300 ppb. Exposure to the herbicide atrazine at environmentally relevant concentrations has been shown to negatively impact aquatic organisms, including crayfish. Because xenobiotics are concentrated in the crayfish hepatopancreas (digestive gland), we examined changes in morphology and DNA damage in hepatopancreatic tissue structure and cells following a 10-day exposure to atrazine (0, 10, 40, 80, 100 and 300 ppb). We found that there were marked morphological changes, post-exposure, for all atrazine concentrations tested. Hepatopancreatic tissue exhibited degenerated tubule epithelium with necrosis of microvilli, tubule lumen dilation, changes in tubular epithelium height and vacuolization of the epithelium. Likewise, we also performed a terminal deoxynucleotidyl transferase (TdT) mediated dUTP nick-end labeling (TUNEL) assay which showed the percentage of cells with DNA damage increased following atrazine exposure. Crayfish hepatopancreatic tissue displayed significant increases in TUNEL-positive cells following exposure to atrazine at 100 ppb and above. Overall, exposure to atrazine at environmentally relevant concentrations damages hepatopancreatic tissue. This impairment could lead to changes in biotransformation, detoxification, digestion and molting, subsequently reducing crayfish populations and negatively impacting the aquatic ecosystem.
... Understanding the impacts of ATR exposure on non-target aquatic organisms has been the focus of many reviews (Giddings, 2005;Solomon et al., 2008;Van Der Kraak et al., 2014;de Albuquerque et al., 2020). Because ATR comes into contact with a broad range of aquatic organisms, it can cause sublethal effects to nontarget species and interfere with the behavior, morphology and physiology of many species at environmentally relevant concentrations. ...
Exposure to the herbicide atrazine at environmentally relevant concentrations has been shown to negatively impact aquatic organisms, including crayfish. Because xenobiotics are concentrated in the crayfish hepatopancreas (digestive gland), we examined changes in morphology and DNA damage in hepatopancreatic tissue structure and cells following a 10-day exposure to atrazine (0, 10, 40, 80, 100 and 300 ppb). We found that there were marked morphological changes, post-exposure, for all atrazine concentrations tested. Hepatopancreatic tissue exhibited degenerated tubule epithelium with necrosis of microvilli, tubule lumen dilation and vacuolization of the epithelium. These changes increased in a dose-dependent manner. Likewise, we also performed a terminal deoxynucleotidyl transferase (TdT) mediated dUTP nick-end labeling (TUNEL) assay which showed the percentage of cells with DNA damage increased following atrazine exposure. Crayfish hepatopancreatic tissue displayed significant increases in TUNEL-positive cells following exposure to atrazine at 100 ppb and above. Overall, exposure to atrazine at environmentally relevant concentrations damages hepatopancreatic tissue, leading to an inability to detoxify atrazine and a potential to bioaccumulate atrazine long-term.
... Atrazine can be transported off-field into adjacent surface waters following application, primarily through precipitation-driven run-off events (Andrus et al. 2013(Andrus et al. , 2015. These events, coupled with a relatively long aquatic half-life that has been reported as up to > 200 days, result in frequent detections of atrazine in surface waters near points of application, but rarely above peak concentrations of 100 μg/L or greater (Andrus et al. 2013;2015;Giddings et al. 2005;Mahler et al. 2017). As of 2020, more than 30 studies for 14 species have been conducted to evaluate potential effects of atrazine on the survival, growth, and reproduction of Anurans. ...
This paper presents a semiquantitative method to help ecotoxicologists evaluate the consistency of data within the available peer-reviewed literature. In this case study, we queried whether there is consistent evidence of direct toxicity in Anurans exposed to atrazine at concentrations ≤ 100 μg/L under laboratory conditions. Atrazine was selected because of the relatively large repository of Anuran toxicity data. To accomplish this, we interrogated available data found in recent quantitative weight-of-evidence risk assessments for atrazine with a series of yes or no questions developed a priori. The questions examined consistency of reported effects within and between studies, within and between species, and across a wide range of endpoints categories (e.g., survivorship, growth and development, reproduction). The analysis found no compelling evidence of a consistent direct effect in Anurans around growth and development, reproduction, or survivorship at concentrations of up to at least 100 μg/L atrazine in laboratory studies. Further work is needed to refine the approach, including accounting for the magnitude of the reported effects. However, we recommend that ecotoxicologists employ some method of formal consistency of effects assessment method routinely before performing toxicity tests, in the contextualizing of new data, and in reviews of contaminants.
... Following application and in part due to its solubility (33 mg/L at 20°C), atrazine can be transported off-field, primarily through rain-mediated run-off events (Andrus et al., 2013(Andrus et al., , 2015. This, coupled with a relatively long aquatic half-life (up to N200 days) and extensive use in agriculture, results in frequent detections of atrazine in surface waters near points of application, typically as brief pulses and rarely at peak concentrations of 100 μg/L or greater (e.g., Andrus et al., 2013Andrus et al., , 2015Giddings et al., 2005;Mahler et al., 2017). Chronic exposures (those occurring over several weeks) have been reported for rivers and ponds, and these are usually less than 1 μg/L (e.g., US EPA, 2019; Challis et al., 2018). ...
Fathead minnows (Pimephales promelas) were continuously exposed to the herbicide atrazine (0.15, 0.25, 0.46, 0.99, and 2.0 mg a.i./L, plus dilution water and solvent controls) for a complete life cycle (274 days). Concentrations of atrazine up to 2.0 mg a.i./L did not significantly reduce hatching success, larval survival at 30 or 60 days post-hatch, or reproduction (eggs/spawn, total eggs, spawns/female, or eggs/female) in the F0 generation. However, at 60 days of exposure, total length and total survival to study completion were significantly reduced in ≥0.46 mg a.i./L and ≥ 0.99 mg a.i./L treatments, respectively. In the F1 generation, hatchability of embryos at ≥0.25 mg a.i./L (range 74–82%) was significantly less than that of pooled control organisms (86%). Following 30 days' post-hatch exposure, F1 survival was not significantly different from pooled control for any treatment. Finally, tissues representing major life stages had bioconcentration factors ranging from 3.7× (F1 embryos, <24 h) to 8.5× (F0 adults), indicating little to no evidence of bioconcentration. We developed a series of questions to assess the consistency of observed responses in order to place the data in context with the wider available and relevant literature (e.g., Observed between studies? Observed between species? Observed at lower levels of biological organization?). The analysis for consistency supports the conclusion that atrazine does not pose a significant chronic risk to freshwater fish in terms of growth, reproduction, or survivorship at concentrations of up to at least 100 μg/L.
... Case Study #3 compared modeling and monitoring exposure data for the herbicide, atrazine. Environmental fate parameters reported by Giddings et al. (2005) were used to parameterize the PWC model to generate a daily exposure profile for the Nebraska Corn scenario. Two (2) ground applications (at 2.24 kg a.i./ha and 0.56 kg a.i./ha) were assumed with a 28-d application interval. ...
Risk curves describe the relationship between cumulative probability and magnitude of effect and thus express far more information than risk quotients. However, their adoption has remained limited in ecological risk assessment. Therefore, we developed the Ecotoxicity Risk Calculator (ERC) to simplify the derivation of risk curves, which can be used to inform risk management decisions. Case studies are presented with crop protection products, highlighting the utility of the ERC at incorporating various data sources, including surface water modeling estimates, monitoring observations, and species sensitivity distributions. This article is protected by copyright. All rights reserved.
... Atrazine (ATZ) which is used on crops such as corn, sugarcane, pineapples and macadamia nuts is one of the most widely used herbicides in North America with ∼65-80 million pounds being used per year in the U.S.A. [135]. Atrazine belongs to the chloro-s-triazine class of compounds which are metabolized by animals, plants and microbes yielding very persistent metabolites with a half-life of greater than 1 or 2 years in soil and water, respectively [136]. In fact 14 C-labeled ATR was detected in soil up to 22 years after application [137]. ...
Obesity is a leading cause of morbidity, mortality and health care expenditure whose incidence is rapidly rising across the globe. Although the cause of the obesity epidemic is typically viewed as a product of an increased availability of high calorie foods and/or a reduction in physical activity, there is mounting evidence that exposure to synthetic chemicals in our environment may play an important role. Pesticides, are a class of chemicals whose widespread use has coincided with the global rise of obesity over the past two decades. Importantly, given their lipophilic nature many pesticides have been shown to accumulate with adipose tissue depots, suggesting they may be disrupting the function of white adipose tissue (WAT), brown adipose tissue (BAT) and beige adipose tissue to promote obesity and metabolic diseases such as type 2 diabetes. In this review, we discuss epidemiological evidence linking pesticide exposure with body mass index (BMI) and the incidence of diabetes. We then review preclinical studies in rodent models which have directly evaluated the effects of different classes of insecticides and herbicides on obesity and metabolic dysfunction. Lastly, we review studies conducted in adipose tissue cells lines and the purported mechanisms by which pesticides may induce alterations in adipose tissue function. The review of the literature reveals major gaps in our knowledge regarding human exposure to pesticides and our understanding of whether physiologically relevant concentrations promote obesity and elicit alterations in key signaling pathways vital for maintaining adipose tissue metabolism.
... Thus, the 100 mg/L cutoff for assessing environmental relevance used in this and the previous assessment (Van Der Kraak et al. 2014) is very conservative and appropriate based on worst-case measured concentrations in surface water measured over the past 15 years. For the purposes of identifying smaller environmentally relevant concentrations to characterize the range of concentrations used in toxicity studies, this QWoE update continues to use the value of 20 mg/L derived from higher-tier microcosm studies evaluated in Giddings et al. (2005) and in Giddings et al. (2018). The individual QWoE assessments for the new papers and reports are provided in the SI in this paper. ...
Quantitative weight of evidence (QWoE) provides a framework and process for evaluating different toxicological studies based on quality and relevance of the results. This framework allows for data from these studies to be combined in separate lines of evidence to address causality, and relevance to environmental risks. In 2014, such a QWoE that examined the body of available company reports and peer reviewed literature regarding the effects of the herbicide atrazine on fish, amphibians, and reptiles was published. Since that time, new studies have been conducted and/or published. One of the advantages of the QWoE framework is that additional information can be added as it becomes available. Thus, these new studies were evaluated in the same manner as previously and the new data incorporated into the existing QWoE. As before, the new updated QWoE was based on the same process of objective scoring of individual studies with respect to the quality of the methods and the relevance of individual responses to the apical endpoints of survival, growth, development, and reproduction. These new data did not identify new responses or indicate any relevant effects of atrazine. The new updated QWoE analysis concluded that atrazine does not adversely affect fish, amphibians, and reptiles, at environmentally relevant concentrations (<100 µg atrazine/L), which is consistent with the previous conclusions. These new studies and data are discussed in this paper and the accompanying supplement information provides detailed and transparent information to support these conclusions.
... 物种敏感度分布模型是效应分析 不确定性的来源之一. 尽管 SSD 方法已被广泛应用 于生态风险评价中, 但 SSD 方法仍是具有争议 [53,54] . ...
... Atrazines are classified under the group of herbicides known as the S-triazine group, and they are important water contaminants which pollute various water bodies, including marine and freshwater (Tasli et al. 2009). Its mechanism of activity in weeds and other plants has been reported to include disruption of biological structures and processes, or the promotion of uncontrolled growth and inhibition of photosynthesis (William et al. 2008;Dodge et al. 2010;Giddings et al. 2011). Atrazine can remain in water bodies over long periods, especially in bodies of water with high pH. ...
... 102 749 "Concentrations of atrazine have been reported to exceed 20 µg/L only on rare occasions, even directly after application (Battaglin et al. 2000;Solomon et al. 1996;Giddings et al. 2005)." X Positive - Solomon et al. (2008) provide numerous citations where atrazine has exceeded 20 µg/L. ...
... Pesticide environmental fate properties. The primary source for atrazine environmental fate characteristics was Giddings et al. (2005), with additional values required by SWAT obtained from the SWAT pesticide properties database (Knisel 1993 An ensemble simulation method and novel approach for determining pesticide application timing. The uncertainty in pesticide application timing was addressed within each watershed by implementing an ensemble simulation approach that generated multiple pesticide application input scenarios and resulting atrazine concentration predictions. ...
Recent national regulatory assessments of potential pesticide exposure of threatened and endangered species in aquatic habitats have led to increased need for watershed-scale predictions of pesticide concentrations in flowing water bodies. This study was conducted to assess the ability of the un-calibrated Soil and Water Assessment Tool (SWAT) to predict annual maximum pesticide concentrations in the flowing water bodies of highly vulnerable small- to medium-sized watersheds. SWAT was applied to 27 watersheds, largely within the Midwest corn belt of the US, ranging from 20-386 km2, and evaluated using consistent input datasets and an un-calibrated parameterization approach. The watersheds were selected from the Atrazine Ecological Exposure Monitoring Program and Heidelberg Tributary Loading Program, both of which contain high temporal resolution atrazine sampling data from watersheds with exceptionally high vulnerability to atrazine exposure. The model performance was assessed based upon predictions of annual maximum atrazine concentrations in 1-day and 60-day durations, predictions critical in pesticide threatened and endangered species risks assessments when evaluating potential acute and chronic exposure to aquatic organisms. The simulation results showed that for nearly half of the watersheds simulated, the un-calibrated SWAT model was able to predict annual maximum pesticide concentrations within a narrow range of uncertainty resulting from atrazine application timing patterns. Un-calibrated model's predictive performance is essential for the assessment of pesticide exposure in flowing water bodies, the majority of which have insufficient monitoring data for direct calibration, even in data-rich countries. In situations where SWAT over or under predicted the annual maximum concentrations, the magnitude of the over/under prediction was commonly under a factor of two, indicating that the model and un-calibrated parameterization approach are a capable method for predicting the aquatic exposure required to support pesticide regulatory decision-making. This article is protected by copyright. All rights reserved
... Risk curves were derived by integrating exposure distributions with an effects distribution to indicate the probability of exceeding effects of differing magnitudes (ECOFRAM 1999;USEPA 2004;Giddings et al. 2005). Acute risk curves for fish were derived by integrating the acute SSD with 96-h EEC distributions, and for aquatic invertebrates the acute and chronic SSDs were integrated with 48-h and 21-d EECs, respectively. ...
The California red-legged frog (CRLF), delta smelt (DS), and the California tiger salamander (CTS) are three species listed under the United States Federal Endangered Species Act (ESA), all of which inhabit aquatic ecosystems in California. The US Environmental Protection Agency (USEPA) has conducted deterministic screening-level risk assessments for these species potentially exposed to malathion, an organophosphorus insecticide and acaricide. Results from our screening-level analyses identified potential risk of direct effects to DS as well as indirect effects to all three species via reduction in prey. Accordingly, for those species and scenarios in which risk was identified at the screening-level, we conducted a refined probabilistic risk assessment for CRLF, DS, and CTS. The refined ERA was conducted using best available data and approaches, as recommended by the 2013 National Research Council (NRC) report Assessing Risks to Endangered and Threatened Species from Pesticides. Refined aquatic exposure models including the Pesticide Root Zone Model (PRZM), the Vegetative Filter Strip Modeling System (VFSMOD), the Variable Volume Water Model (VVWM), the Exposure Analysis Modeling System (EXAMS), and the Soil and Water Assessment Tool (SWAT) were used to generate estimated exposure concentrations (EECs) for malathion based on worst-case scenarios in California. Refined effects analyses involved developing concentration-response curves for fish and species sensitivity distributions (SSDs) for fish and aquatic invertebrates. Quantitative risk curves, field and mesocosm studies, surface water monitoring data, and incident reports were considered in a weight-of-evidence approach. Currently labeled uses of malathion are not expected to result in direct effects to CRLF, DS or CTS, or indirect effects due to effects on fish and invertebrate prey. This article is protected by copyright. All rights reserved.
... However, the total triazine loads measured in the 0.1 and 10 mg/ L treatment were only 0.12 and 10.35 mg/L, respectively (Table 1). Although related triazines and degradation products can produce similar endocrine effects as atrazine itself, there is no evidence that they are substantially more potent [44]. Thus, unless unknown proprietary ingredients amplified responses, the most likely explanation for the low threshold of response observed here is that cricket frogs are sensitive to the effects of atrazine on sex ratio. ...
We exposed Blanchard's cricket frogs (Acris blanchardi) to ecologically relevant concentrations (0, 0.1, 1, and 10 μg/L) of a commercial formulation of atrazine throughout the larval period to determine effects on survival, somatic growth and development (time to metamorphosis and mass at metamorphosis), and gonadal development (sex ratio at metamorphosis and the prevalence of testicular ova in phenotypic males). We tested the following hypotheses: 1) atrazine feminizes the sex ratio, 2) atrazine increases the proportion of phenotypic males with testicular ova, and 3) atrazine differentially affects somatic growth (mass at metamorphosis) and development (time to metamorphosis) for males and females. Although the control sex ratio was male-biased, exposure to 0.1 and 10 μg/L atrazine feminized sex ratios, because these treatments produced 51 and 55% fewer males than the control, respectively. We did not observe testicular ova. Atrazine did not impact survival or metamorphosis, and we did not detect sexually dimorphic impacts on time to metamorphosis or mass at metamorphosis. However, males metamorphosed 2.3 d later than females, regardless of treatment. Sex biases in timing of metamorphosis are underexplored in anurans, but if prevalent, could have important implications for theory surrounding the impact of environmental factors on metamorphosis. Our data suggest that cricket frog sex ratios are sensitive to environmentally relevant concentrations of atrazine and that feminization in the field is likely. Environ Toxicol Chem 2017;9999:1–9.
... The methodologies employed for the hazard assessment did not strictly follow any one particular regulatory guideline, but specific approaches from some of the most recent and relevant guidelines (CCME, 2007;EC, 2011;EFSA, 2013;US EPA, 2010) were applied based on their applicability to the questions asked in this study. Probabilistic risk assessment methodologies were based on those commonly employed in the assessment of plant protection products (Giddings et al., 2005;Solomon et al., 2000;Solomon and Sibley, 2002;Solomon and Thompson, 2003). ...
This study presents one of the most complete applications of probabilistic methodologies to the risk assessment of emerging contaminants. Perhaps the most data-rich of these compounds, caffeine, as well as its main metabolite (paraxanthine), were selected for this study. Information for a total of 29,132 individual caffeine and 7442 paraxanthine samples was compiled, including samples where the compounds were not detected. The inclusion of non-detect samples (as censored data) in the estimation of environmental exposure distributions (EEDs)
allowed for a realistic characterization of the global presence of these compounds in aquatic systems. EEDs
were compared to species sensitivity distributions (SSDs), when possible, in order to calculate joint probability
curves (JPCs) to describe the risk to aquatic organisms. This way, it was determined that unacceptable environmental
risk (defined as 5% of the species being potentially exposed to concentrations able to cause effects in N 5%
of the cases) could be expected fromchronic exposure to caffeine fromeffluent (28.4% of the cases), surfacewater (6.7% of the cases) and estuary water (5.4% of the cases). Probability of exceedance of acute predicted no-effect concentrations (PNECs) for paraxanthine were higher than 5% for all assessed matrices except for drinking water and groundwater, however no experimental effects datawas available for paraxanthine, resulting in a precautionary deterministic hazard assessment for this compound.
... Among the pesticides, due to the agricultural activities, herbicides represent a large percent of all used pesticides worldwide. One of the most common herbicide is atrazine, which affects the photosynthesis in broad leaf plants and has well known effects on different non-target organisms including frogs, birds, fish and even humans (Giddings et al., 2004). ...
Environmental contaminants, such as heavy metals and pesticides, are the most important toxic compounds of aquatic habitats. Heavy metals enter the aquatic environments via natural and anthropogenic pathways while the only source of pesticides is the anthropogenic usage of different types of pesticides including fungicide, insecticide and herbicide. Fish larvae and fingerlings are the most vulnerable life stages of fish which could be severely affected by pesticides as non-target organisms as well as by heavy metal pollution. The most important tissues affected by these pollutants are the gill, kidney and liver. Histopathological alterations of these vital organs could affect the survival rate, biological activities, osmoregulation, reproduction, buoyancy, etc., which finally could lead to failures in stock recruitment and population changes.
... Non-linear sorption is described with the Freundlich isotherm. Atrazine (6-chloro-N2-ethyl-N4-isopropyl-1, 3, 5-triazine-2, 4-diamine) has relatively low adsorption coefficient with K oc values ranging from 40 to 394 mill/g for atrazine (Giddings et al., 2005): ...
... Atrazine blocks the flow of electrons between photosystem II (PSII) and photosystem I (PSI) by reversibly binding to the electron carrier plastoquinone, which halts the production of NADPH and ATP required in the Calvin cycle and also resulting in photo-oxidative stress within chlorophyll containing cells (Forney and Davis, 1981;Hess, 2000;Moreland, 1980). As well, atrazine has a relatively low affinity for organic carbon in soil, is moderately soluble in water, and can persist in the field for months after application (Giddings et al., 2005;Solomon et al., 1996). Consequently, exposure to atrazine in aquatic systems is usually acute and pulsed as a consequence of transport by surface run-off events. ...
The acute toxicity of herbicides to algae is commonly assessed under conditions (e.g., light intensity, water temperature, concentration of nutrients, pH) prescribed by standard test protocols. However, the observed toxicity may vary with changes in one or more of these parameters. This study examined variation in toxicity of the herbicide atrazine to a representative green algal species Raphidocelis subcapitata (formerly Pseudokirchneriella subcapitata) with changes in light intensity, water temperature, concentrations of nutrients or combinations of these three parameters. Conditions were chosen that could be representative of the intensive corn growing Midwestern region of the United States of America where atrazine is used extensively. Varying light intensity (4–58 µmol/m2 s) resulted in no observable trend in 96-h EC50 values for growth rate. EC50 values for PSII yield generally increased with decreasing light intensity but not significantly in all cases. The 96-h EC50 values for growth rate decreased with decreases in temperature (20–5 °C) from standard conditions (25 °C), but EC50 values for PSII yield at lower temperatures were not significantly different from standard conditions. Finally, there was no clear trend in 96-h EC50 values for both endpoints with increases in nitrogen (4.1–20 mg/L) and phosphorus (0.24–1.2 mg/L). The 96-h EC50 values for both endpoints under combinations of conditions mimicking aquatic systems in the Midwestern U.S. were not significantly different from EC50 values generated under standard test conditions. This combination of decreased light intensity and temperature and increased nutrients relative to standard conditions does not appear to significantly affect the observed toxicity of atrazine to R. subcapitata. For atrazine specifically, and for perhaps other herbicides, this means current laboratory protocols are useful for extrapolating to effects on algae under realistic environmental conditions.
... The estimated 90th centile concentration was used as an ''exposure descriptor'' (Solomon et al. 1996), because it is used in the conduct of aquatic ecological risk assessments. The 90th percentile concentration estimate assumes that 90 % of the exposure concentration samples will be below this descriptor if it comes from an exposure distribution that is unbiased and that accurately represents the concentrations found for a location during a given time period (Giddings et al. 2005). Table 1 summarizes the TPAH concentrations in WAF (100 %) exposures for the laboratory chronic toxicity tests. ...
Chronic, 21-28-day toxicity tests of Macondo source (Massachusetts, or MASS) and weathered Slick A (CTC) and Slick B (Juniper) oils field collected during the 2010 Deepwater Horizon (DWH) Incident in the Gulf of Mexico (GOM) were conducted using standardized procedures. Standard species, Americamysis bahia and Menidia beryllina, were evaluated for changes in survival and growth during daily static-renewal tests. Both species demonstrated an increased sensitivity to low-energy water accommodated fractions (WAFs) of un-weathered MASS oil, with growth and survival decreasing as oil loading rate increased from 0.01 to 1.0 g/L. Survival and growth of mysid shrimp exposed to weathered oil (Slick A and Slick B) did not differ from that of test controls. In contrast, survival and growth of inland silversides declined relative to that of test controls at loading rates of 1 g/L for both weathered oils. Based on the concentration of total polycyclic aromatic hydrocarbons (TPAH42), no observed effect concentrations were lower for inland silverside survival (5.00-7.61 µg/L) and growth (<2.02 to <7.61 µg/L) in chronic exposures to Slick B and Slick A weathered oils compared with mysids (4.75-17.9 µg/L). Average TPAH concentrations in full strength WAFs followed the weathering trend, with 165 ± 17.2, 17.9 ± 0.480, and 4.75 ± 0.521 µg/L for MASS, Slick A, and Slick B oils, respectively. The effect (LOEC, IC25) and no-effect exposure concentrations (in TPAHs) from the standardized laboratory toxicity studies with un-weathered and weathered oils are discussed relative to the actual exposure concentrations in the GOM in 2010. The exposures evaluated in the laboratory toxicity tests represent the highest concentrations of total PAHs that were rarely observed in water column samples collected in the GOM during the release and post release periods of the DWH incident.
... For example, atrazine concentrations in lentic surface waters have been reported at 131 mg/L in Mississippi (USA) [40], 681 mg/L in Ontario (Canada) [41], 850 mg/L in Florida (USA) [42], 1068 mg/L in Kansas (USA) [43], 1096 mg/L in Nebraska (USA) [44], and 2300 mg/L in Iowa (USA) [45]. These findings seem to belie probabilistic aquatic ecological risk assessments for atrazine that suggest that concentrations near or above the EEC are extremely rare [46] and demonstrate that measured concentrations of atrazine near and well above the EEC are widespread. In summary, the EEC is the concentration the USEPA estimates to enter farm ponds regularly and is not a worst-case scenario, because it was exceeded in at least 4 states in the United States and in Canada. ...
The ability to detect chemical cues is often critical for freshwater organisms to avoid predation and find food and mates. In particular, reduced activity and avoidance of chemical cues signaling predation risk are generally adaptive behaviors that reduce prey encounter rates with predators. Here, we examined the effects of the common herbicide atrazine on the ability of Cuban tree frog (Osteopilus septentrionalis) tadpoles to detect and respond to chemical cues from larval dragonfly (Libellulidae sp.) predators. Tadpoles exposed to an estimated environmental concentration of atrazine (calculated using US EPA software; measured concentration: 178 µg/L) were significantly hyperactive relative to those exposed to solvent control. Additionally, control tadpoles significantly avoided predator chemical cues, but tadpoles exposed to atrazine did not. These results are consistent with previous studies that have demonstrated that ecologically relevant concentrations of atrazine can induce hyperactivity and impair the olfactory abilities of other freshwater vertebrates. We call for additional studies examining the role of chemical contaminants in disrupting chemical communication and the quantification of subsequent impacts on the fitness and population dynamics of wildlife. This article is protected by copyright. All rights reserved.
... A complete and detailed analysis of concentrations of herbicides in surface waters is beyond the scope of this chapter; however, concentrations of herbicides in surface wasters are, in general, low in comparison to their toxicity (see below). Even for pesticides that are relatively mobile and relatively persistent in surface waters, such as atrazine, 90th centiles of measured and predicted concentrations in surface waters are o20 mg/L (Giddings et al., 2005), well below the acute lethality or chronic toxicity of this herbicide for fish. ...
Herbicides are used to control weeds and are usually targeted to processes and target sites that are specific to plants. As a result, most herbicides are not acutely toxic to fish. Exceptions to this general rule are uncouplers of oxidative phosphorylation and some herbicides that interfere with cell division. Chronic and sublethal effects have been studied for some herbicides, but fewer data are available for these effects than for acute effects. The sublethal effects of herbicides that have been studied include reproduction, stress, olfaction, and behavior. Although some of these responses have been observed in fish exposed to herbicides, these have either been observed at large concentrations that would be rarely found in surface waters inhabited by fish or, as in the case of behavior and olfaction, have not been linked to ecologically relevant responses on survival, growth, development, and reproduction. As with all pesticides, herbicides may have indirect effects in fish. These effects are mediated by herbicide-induced changes in food webs or in the physical environment. Indirect effects can only occur if direct effects occur first and would be mediated by the killing of plants by herbicides. Although this indirect effect might occur when plants are controlled by direct treatment of surface waters, indirect effects appear to be unlikely to result from use of herbicides in terrestrial systems as runoff concentrations in surface waters are, for the most part, very much less than those that could directly affect plants.
Risk assessment of pesticides has its roots in the same process for chemicals in general, both of which are relatively recent. Pesticides such as oxides of sulfur and some minerals were also used by early civilizations but the concepts of dose-response and risk as a probability were only documented in the literature (books) in the 1500s and 1600s, respectively. Formal use of toxic dose and safety factors for humans was developed as inorganic and organic pesticides entered the market after the 1930s, but only made use of simple hazard ratios to characterize danger. This approach continued until adoption of the concept of probability of exposure of humans to pesticides via dietary exposure, but not sensitivity of humans. It was in 1980s–90s that the use of probability was suggested as a way of characterizing variation in sensitivity of species in the environment as well as the exposures in environmental matrices. As we move into the future, risk assessment of agrochemicals will evolve to include new frameworks and approaches for dealing with conflicting data, such as Weight of Evidence.
In modern agriculture, the gap between food production and food consumption caused by the exponential increase in the global population is bridged with the use of agrochemicals. The chapter seeks to highlight the human and animal disease implications of agrochemical use. Fertilizers, soil conditioners, liming and acidifying agents, pesticides, antibiotics, and hormones are commonly used agrochemicals in crop and livestock farming. These agrochemicals are effective in controlling weeds, increasing agricultural productivity, and extending the shelf-life of farm produce but also have nontargeted negative effects on the environment, biodiversity, and human health. Human diseases such as cardio-neurotoxicity (Alzheimer, Parkinson, autism, etc.), endocrine disruption, liver and kidney damage, cancers (non-Hodgkin’s lymphoma), leukemia, brain tumors, different cancers, reproductive defects, diabetes, obesity, respiratory diseases, and different organ and system diseases in humans and animals have been connected to the abuse and misuse of agrochemicals. The need for the proper use of agrochemicals is a necessity to prevent known and emerging diseases caused by agrochemical applications. Emerging effects include pharmaceutical and chemical resistance in humans and animals while disease resistance has also been linked to agrochemical exposure. Farmers should be trained on best practices and appropriate methods of agrochemical application, utilization, and disposal. On the other hand, farmers and agricultural workers need to reduce their overdependence on agrochemicals for food production and preservation by seeking alternative methods of improving food production while maintaining human, animal, and environmental health.
Dans le but de proposer une démarche pour la gestion des risques liés aux pesticides à usage agricole, une enquête a été réalisée auprès de 40 agriculteurs sélectionnés de manière aléatoire à travers les différentes communes de la wilaya de Boumerdès. Des risques sur la santé humaine et sur l’environnement ont été évalués. Face à cette situation, une démarche de gestion des risques liés à l’utilisation des pesticides a été proposée. Également, cette enquête a fait ressortir un certain nombre de recommandation afin de réduire les risques les plus inquiétants sur la santé humaine et les risques qui peuvent conduire à la pollution de l’environnement.
The US Environmental Protection Agency (US EPA) and the Services (National Marine Fisheries Service, Fish and Wildlife Service) are required to assess the risks of pesticides undergoing registration or re‐registration to threatened and endangered (i.e., listed) species. Currently, the US EPA lacks a refined model to assess the potential risks of seed treatments to listed bird species. We developed the Endangered Species Assessment Seed Treatment Probabilistic Avian Risk Assessment Model (ESASeedPARAM) to incorporate species‐specific diets, body weights, and food ingestion rates for potentially exposed listed bird species. The model also incorporates information on dissipation of seed residues following planting, and metabolism and elimination by birds during exposure. The ESASeedPARAM estimates hourly intake from ingestion of treated seeds for up to 50 days following planting. For each simulated bird, maximum retained dose (=body burden) and maximum rolling average total daily intake are estimated for acute and chronic exposure, respectively. The model is probabilistic and estimates exposure and risk for 20 birds on each of 1000 fields. The model accounts for inter‐field variation in the amount of waste grain on the soil surface in tilled, reduced till and untilled fields. To estimate the fate of each bird from acute exposure, a random value is selected from the appropriate dose‐response relationship and compared to the maximum retained dose. If acute exposure exceeds the randomly chosen effects value, mortality is assumed. For chronic risk, the most sensitive No Observed Adverse Effects Level (NOAEL) and Lowest Observed Adverse Effects Level (LOAEL) for an apical endpoint (survival, growth, reproduction) are compared to maximum rolling average total daily intake. In this paper, we describe a case study conducted with the ESASeedPARAM for imidacloprid used as a seed treatment in wheat and soybean. This article is protected by copyright. All rights reserved.
Water contamination caused by atrazine (ATZ) application in agriculture is a risk to the environment and human health. Common analytical methods are expensive and complex. A sensor for low-cost and simple detection of ATZ and its metabolites, deethylatrazine (DEA) and deisopropylatrazine (DIA), in aqueous solutions was developed by combining colloidal crystal with molecular imprinting technique. The sensor is formed by 3D interconnected macroporous structure with numerous nanocavities derived from ATZ and its metabolites imprinting in a thin polymeric film. Molecularly Imprinted Polymers (MIPs) were characterized by Fourier Transform Infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) and were incubated in solutions at variable concentrations. Target molecules were specifically absorbed in nanocavities and caused swelling in the polymer resulting in changes of Bragg diffraction peak wavelength. Kinetic tests showed that rebinding equilibrium was reached within 20 minutes. The sensor had a dynamic range of 0.1 to 10 ppb for quantifying target analytes in aqueous solutions with limit of detection of 0.1, 0.2, and 0.3 ppb, and limit of quantification of 0.33, 0.66, and 1 ppb for ATZ, DEA, and DIA, respectively. Cross-reactivity tests were conducted in 1 and 5 ppb solutions combining all three targets and showed absence of positive interference effects and low probability of false positives given by individual sensors. MIPs were examined in natural waters containing ATZ and its metabolites contamination, showing good agreement with real concentrations of targets. The MIP yields rapid and efficient detection of target molecules in aqueous solutions close to environmentally relevant concentrations.
Estimating exposure in receiving water bodies is a key step in the regulatory process to evaluate potential ecological risks posed by the use of agricultural pesticides. The United States Environmental Protection Agency (USEPA) currently uses the Variable Volume Water Model (VVWM) to predict environmental concentrations of pesticides in static water bodies (ponds) that receive edge‐of‐field runoff inputs from the Pesticide Root Zone Model (PRZM). This regulatory model, however, does not adequately characterize potential pesticide concentrations in flowing water systems (streams and rivers) drained from watershed areas. This study aims at addressing this gap by coupling the regulatory PRZM model with a watershed‐level hydrological model, the Soil and Water Assessment tool (SWAT), to predict pesticide concentrations in flowing water habitats for aquatic organisms. This coupled PRZM‐SWAT model was applied in a test watershed (~HUC12), a headwater watershed of Goodwater Creek in Missouri, and simulation results at the outlet of this watershed were compared to daily and near‐daily measured streamflow and atrazine concentration data from a decade‐long sampling campaign. Overall, the PRZM‐SWAT model captured 1) the general magnitude and temporal trend of daily atrazine concentrations, 2) the observed high‐end of exposure levels (> 3ppb) of atrazine concentrations, and 3) the 90th centile annual maximum for various exposure durations (1‐, 4‐, 7‐, 21‐, and 60‐day rolling average), which are important exposure metrics used in assessing the potential ecological risks posed by the application of pesticides. The PRZM‐SWAT model is expected to expand the utility of the field‐scale regulatory model to include pesticide exposure prediction capability in flowing waterbodies from agricultural watersheds. This article is protected by copyright. All rights reserved.
Atrazine is a triazine herbicide used predominantly on corn, sorghum, and sugarcane in the US. Its use potentially overlaps with the ranges of listed (threatened and endangered) species. In response to registration review in the context of the Endangered Species Act, we evaluated potential direct and indirect impacts of atrazine on listed species and designated critical habitats. Atrazine has been widely studied, extensive environmental monitoring and toxicity data sets are available, and the spatial and temporal uses on major crops are well characterized. Ranges of listed species are less well-defined, resulting in overly conservative designations of "May Effect". Preferences for habitat and food sources serve to limit exposure among many listed animal species and animals are relatively insensitive. Atrazine does not bioaccumulate, further diminishing exposures among consumers and predators. Because of incomplete exposure pathways, many species can be eliminated from consideration for direct effects. It is toxic to plants, but even sensitive plants tolerate episodic exposures, such as those occurring in flowing waters. Empirical data from long-term monitoring programs and realistic field data on off-target deposition of drift indicate that many other listed species can be removed from consideration because exposures are below conservative toxicity thresholds for direct and indirect effects. Combined with recent mitigation actions by the registrant, this review serves to refine and focus forthcoming listed species assessment efforts for atrazine. Abbreviations: a.i. = Active ingredient (of a pesticide product). AEMP = Atrazine Ecological Monitoring Program. AIMS = Avian Incident Monitoring SystemArach. = Arachnid (spiders and mites). AUC = Area Under the Curve. BE = Biological Evaluation (of potential effects on listed species). BO = Biological Opinion (conclusion of the consultation between USEPA and the Services with respect to potential effects in listed species). CASM = Comprehensive Aquatic System Model. CDL = Crop Data LayerCN = field Curve Number. CRP = Conservation Reserve Program (lands). CTA = Conditioned Taste Avoidance. DAC = Diaminochlorotriazine (a metabolite of atrazine, also known by the acronym DACT). DER = Data Evaluation Record. EC25 = Concentration causing a specified effect in 25% of the tested organisms. EC50 = Concentration causing a specified effect in 50% of the tested organisms. EC50 RGR = Concentration causing a 50% reduction in relative growth rate. ECOS = Environmental Conservation Online System. EDD = Estimated Daily Dose. EEC = Expected Environmental Concentration. EFED = Environmental Fate and Effects Division (of the USEPA).
Atrazine is ubiquitously used broad-spectrum herbicide to control the weeds in agriculture. The present study aimed to evaluate the acute toxicity and immunotoxicity of Atrazine in two ecologically and economically important bivalves. Acute toxicity of atrazine evaluated in triplicates by taking control and six experimental groups each comprising of 30 animals and treated with a range of atrazine from 2 PPM to 12 PPM for 96 hours. Mortalities were recorded for every 24 hours until 96 hours and data analyzed by one-way ANOVA and Dunnett T-test. The results indicated a significant increase in mortalities with increase in dose and time of exposure in both species. The values of LC50 were determined as 6.10 PPM and 4.90 PPM respectively for Perna viridis and Paphia malabarica. Furthermore, the immunotoxic potential of atrazine assessed by treating mussels and clams with the five sub-lethal doses of atrazine for 14 days and quantifying the viability of hemocytes by using simple yet reliable Tryphan blue exclusion assay. The results of the present study suggest atrazine-induced immunotoxicity by decreasing the number of viable hemocytes in bivalves. Hemocytes with phagocytic function are indispensable to confer innate immunity in bivalves, decreased viability of these cells leads to compromised immunity. This study is first of its kind to implicate atrazine with the immunotoxicity in bivalves.
Atrazine is one of the most frequently used herbicides in Argentina for controlling broadleaf weeds and annual grasses. Currently, there is limited information on the impact of triazine herbicides on mycotoxin production and growth parameters of toxigenic fungi in maize. The objective of this study was to evaluate the effect of different concentrations of atrazine on the lag phase prior to growth, the growth rate, and on production of aflatoxin B1 (AFB1) of Aspergillus flavus and Aspergillus parasiticus strains, on maize meal extract agar (MMEA) under different water activities (aW) and temperatures. A commercial formulation of atrazine was added to MMEA medium at 0, 5, 10, 50, or 100 mmol/l, adjusted to 0.98, 0.95, and 0.93 aW, and incubated at 28 °C and 37 °C for 21 days. AFB1 was determined by HPLC after 7, 14, and 21 days of incubation. In the control treatments, a significant increase in the time prior to growth was observed and as the aW decreased, at both temperatures, the growth rate of the strains also decreased. A significant increase in growth rate was observed as the concentration of atrazine in the medium increased, for all aW levels tested. The optimal conditions for the accumulation of AFB1 in the control treatments were 0.98 aW and 28 °C, after 7 days of incubation. As the concentration of herbicide increased, AFB1 production also increased (P < 0.05). These results add to the knowledge about consequences with regard to aflatoxin production of the use of excessive atrazine doses in extensive maize culture.
In order to learn about the status of heavy metals and ecological risks in Chinese lakes, species sensitivity distributions (SSD) method was applied to assess the ecological risk of six kinds of heavy metal (Zn, Cd, Cr, Cu, Hg and Pb) to freshwater organisms, while principal component analysis was applied to analyze the distributions and source of heavy metal. The evaluation indexes are including the potential affected fractions (PAF) and multi-substance PAF (msPAF), which rank the ecological risk levels. The results showed that among the 18 lakes, the average concentrations of Zn, Pb, Cd, Cu, Cr and Hg were 17.06 μg/L (range is 4.03-29.33 μg/L), 9.33 μg/L (range is 0.04-33.7 μg/L), 5.56 μg/L (range is 0.65-40.0 μg/L), 3.71 μg/L (range is 0.02-10.2 μg/L), 1.17 μg/L (range is 0.01-13.6 μg/L) and 0.19 μg/L (range is 0.03-1.04 μg/L), respectively. The distribution of heavy metal in 18 lakes was reflected by three principal components with the contribution rates of F1 (Cu, Zn and Hg), F2 (Pb and Cd) and F3 (Cr, Cu) were 28.50%, 24.17% and 18.40%, respectively, which was less affected by economic and geographical differences. Different kinds of heavy metal have different HC5 values for all freshwater organisms with Cu for the lowest HC5 value (the order is Cu<Cr<Hg<Cd<Pb<Zn), indicating freshwater organisms have the highest sensitivity to Cu. In the selected 18 lakes, the order of msPAF of heavy metal in each lake was: Lake Hulun (67.0%) > Lake Luhu (56.7%) > Lake Erhai (52.7%) > Lake Jinyin (52.3%) > Lake Taihu (40.5%) > Lake Moshui (39.3%) > Lake Gehu (30.2%) > Lake Poyang (26.8%) > Lake Hongze (23.1%) > Lake Gaobao (22.4%) > Lake Chaohu (20.7%) > Lake Wuliangsu (19.7%) > Lake Donghu (19.1%) > Lake Liangzi (4.0%) > Lake Tangxun (2.0%) > Lake Dongting (1.0%) > Lake Honghu (0) = Lake Luoma (0). Based on the above work, the ecological risks of heavy metal pollution in lakes were evaluated, which provided a scientific theoretical basis for lake risk management and protection.
The toxicity of herbicide degradation (transformation) products is rarely taken into account, even though these are commonly detected in the marine environment, sometimes at concentrations higher than the parent compounds. Here we assessed the potential contribution of toxicity by transformation products of five photosystem II herbicides to coral symbionts (Symbiodinium sp.), the green algae Dunaliella sp., and prawn (Penaeus monodon) larvae. Concentration-dependent inhibition of photosynthetic efficiency (∆F/Fm') was observed for all herbicides in both microalgal species. The toxicity of solutions of aged diuron solutions containing transformation products to Symbiodinium sp. and Dunaliella sp. was greater than could be explained by the concentrations of diuron measured, indicating transformation products contributed to the inhibition of ∆F/Fm'. However, the toxicity of aged atrazine, simazine, hexazinone, and ametryn solutions could be explained by the concentration of parent herbicide, indicating no contribution by transformation products. Prawn larval metamorphosis was not sensitive to the herbicides, but preliminary results indicated some toxicity of the transformation products of atrazine and diuron. Risk assessments should take into account the contribution of herbicide transformation products; however, further studies are clearly needed to test the toxicity of a far wider range of transformation products to a representative diversity of relevant taxa.
Pesticides are detected in streams at concentrations that might have adverse effects on aquatic organisms. These agrochemicals typically occur in streams as combinations, yet research has focused on the effects of individual pesticides. We studied the effects of commercial formulations of atrazine, metolachlor, carbaryl, and chlorothalonil on aquatic gastropods Physa acuta and Helisoma anceps egestion and movement. We observed an eightfold reduction in P. acuta egestion rates when exposed to individual (atrazine: 200 μg/L; metolachlor, carbaryl, and chlorothalonil: 100 μg/L) and combined (atrazine x metolachlor: 200 μg/L x 100 μg/L and carbaryl x chlorothalonil: 100 μg/L x 100 μg/L) pesticide treatments relative to controls. For H. anceps individual and combined pesticide treatments had no significant effects on egestion, highlighting differential species response. Helisoma anceps movement declined when exposed to atrazine, carbaryl, and chlorothalonil individually, though responses varied with exposure time. When combined atrazine + metolachlor and carbaryl + chlorothalonil reduced H. anceps movement relative to the control. In addition to pesticide physicochemical characteristics, it is important to consider exposure durations to better understand the effects of pesticides on aquatic organisms. Furthermore, future risk assessments should incorporate multiple species to better represent response diversity.
Endocrine disrupting chemicals (EDC) are classes of environmental contaminants whose exposure even at very low concentrations interfere with normal endocrine signaling and induce many adverse health effects, including increased risk of birth defects, diabetes, obesity, abnormal reproduction, and cancer. EDC exposure alters the epigenetic programming of cells resulting in altered gene expression and regulation and cell signaling. In this chapter, we have reviewed recent literatures on various well-known EDCs and summarized their potential mechanism of action and health and environmental impacts. These EDCs include BPA, DES, PCBs, phthalates, phytoestrogens, methoxychlor, fungicides, insecticide, herbicide, and some of the heavy metals.
Breeding groups of Japanese medaka (Oryzias latipes) were exposed to atrazine at measured concentrations of 0.6, 5.5, and 53 µg/L for 35 d. Evaluated endpoints included survival, fecundity, fertility, growth (weight and length), behavior, secondary sex characteristics (anal fin papillae), gonad histopathology, and hepatic vitellogenin. No statistically significant effects of atrazine exposure on survival and growth of medaka were noted during the test, and mean survival was ≥97.5% in all treatment groups on Day 35. No significant effects of atrazine exposure on reproduction were observed. The number of mean cumulative eggs produced in the negative control, 0.6, 5.5, and 53 µg/L treatment groups was 7158, 6691, 6883, and 6856 eggs, respectively. The mean number of eggs per female reproductive day was 40.9, 38.2, 40.2, and 39.2 eggs per day, respectively. There were also no dose-dependent effects on mean anal fin papillae counts among male fish or expression of vtg-II in males or females. In addition, atrazine exposure was not related to the development stage of test fish, with testes stages ranging from 2 to 3 in all groups and ovaries ranging from stage 2 to 2.5. Overall, exposure to atrazine up to 53 µg/L for 35 d did not result in significant, treatment-related effects on measured endpoints related to survival, growth, or reproduction in Japanese medaka. This article is protected by copyright. All rights reserved.
Wildlife toxicology is the study of potentially harmful effects of toxic agents in wild animals, focusing on amphibians, reptiles, birds, and mammals. Fish and aquatic invertebrates are not usually included as part of wildlife toxicology since they fall within the field of aquatic toxicology, but collectively both disciplines often provide inSight into one another and both are integral parts of ecotoxicology (Hoffman et al. 2003). It entails monitoring, hypothesis testing, forensics, and risk assessment; encompasses molecular through ecosystem responses and various research venues (laboratory, mesocosm, field); and has been shaped by chemical use and misuse, ecological mishaps, and biomedical research. While human toxicology can be traced to ancient Egypt, wildlife toxicology dates back to the late 19th century, when unintentional poisoning of birds from ingestion oflead shot and predator control agents, alkali poisoning, and die-offs from oil spills appeared in the popular and scientific literature (Rattner 2009).
The sensitivity of 15 aquatic species including primary producers, benthic invertebrates, cladocerans, mollusks and fish to MON 0818, a commercial surfactant mixture of polyoxyethylene tallow amines (POEAs), was evaluated in standard acute (48-96 h) laboratory tests. Additionally, the potential for chronic toxicity (8 d) was evaluated with Ceriodaphnia dubia. Exposure concentrations were confirmed. No significant effects on any endpoint were observed on the chronic test. A Tier-1 hazard assessment was conducted by comparing species sensitivity distributions (SSDs) based on the generated data, as well as literature data, to four exposure scenarios. This assessment showed moderate levels of hazard (43.1% of the species exposed at or above EC50 levels), for a chosen worst-case scenario - unintentional direct over-spray of a 15 cm-deep body of water with the maximum label application rate for the studied formulations (Roundup Original, Vision; 12 L formulation ha(-1) , equivalent to 4.27 kg acid equivalent [a.e.] ha(-1) ). The hazard decreased to impairment of 20.9% of species under the maximum application rate for more typical uses (6 L formulation ha(-1) , 2.14 kg a.e. ha(-1) ), and down to a 6.9% for a more frequently employed application rate (2.5 L formulation ha(-1) , 0.89 kg a.e. ha(-1) ). Finally, the percentage (3.8%) was less than the hazardous concentration for 5% of the species (HC5 ) based on concentrations of MON 0818 calculated from maximum measured concentrations of glyphosate in the environment.
Vegetated filter strips (VFSs) established at the downslope edge of agricultural fields have long been recommended as a management practice to reduce sediment, nutrients, and pesticides in surface runoff before it enters water bodies. Recently VFSs have been mandated as label requirements for plant protection products in Europe and North America. Several simulation models have been developed to predict the amount of pesticide active ingredients and their metabolites removed from runoff flowing through these strips. Removal efficiency is a function of several parameters and must be predicted on an event basis. The predictions of four simulation models (APEX, PRZM-BUFF, REMM, and VFSMOD) were compared using three data sets. Conditions simulated included a range of soil properties, slopes, rainfall events, and pesticide characteristics. All four models predicted reductions of pesticides in the VSFs consistent with the observed reductions, with VFSMOD simulations in closest agreement with the measured data across the three data sets.
The joint probability distribution analysis (JPDA) utilizes the full exposure distribution and the dose-response curve to determine the probability of an adverse effect occurring and the magnitude of the effect. It accounts for uncertainty from variations in exposure concentrations and species sensitivities and can better address the probability of risks of pesticides than the standard, Environmental Protection Agency regulatory risk quotient (RQ) method. In this application, the concern is for effects of dimethoate on salmonid prey which have differing sensitivities. Thus, accounting for variability in response is important. While use of the RQ method indicated potential risks to aquatic invertebrates, results of JPDA showed minimal risks, despite using an exposure model that likely significantly overestimates water concentrations. This paper demonstrates the application of the JPDA methodology to refine an ecological risk assessment and develop more accurate risk estimates.
In this study, the monitoring of pesticide residues, which show potential for environmental contamination, in center-pivot irrigated areas in the Brazilian cerrado, was performed. The pesticides monitored were acephate, atrazine, azoxystrobin, buprofezin, carbofuran, cyproconazole, chlorpyrifos, difenoconazole, diuron, imidacloprid, malathion, methamidophos, metolachlor, metribuzin, monocrotophos, monuron, thiamethoxam, and triazophos. Surface water samples were collected upstream and downstream of Tijunqueiro dam. The subsurface water in piezometric wells was drilled in the surroundings of the irrigated area; fish and sediment were collected in the dam. The technique of solid phase extraction (SPE) was used for the extraction of water samples, the matrix solid phase dispersion (MSPD) for the sediment samples and QuEChERS (quick, easy, cheap, effective, rugged and safe) for the fish samples. The multiresidue methods used were accurate and precise for most pesticides monitored by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Atrazine was detected in two of the subsurface water samples.
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