Article

Chemical Contaminants in Water and Sediment near Fish Nesting Sites in the Potomac River Basin: Determining Potential Exposures to Smallmouth Bass (Micropterus dolomieu)

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Abstract

The Potomac River basin is an area where a high prevalence of abnormalities such as testicular oocytes (TO), skin lesions, and mortality has been observed in smallmouth bass (SMB, Micropterus dolomieu). Previous research documented a variety of chemicals in regional streams, implicating chemical exposure as one plausible explanation for these biological effects. Six stream sites in the Potomac basin (and one out-of-basin reference site) were sampled to provide an assessment of chemicals in these streams. Potential early life-stage exposure to chemicals detected was assessed by collecting samples in and around SMB nesting areas. Target chemicals included those known to be associated with important agricultural and municipal wastewater sources in the Potomac basin. The prevalence and severity of TO in SMB were also measured to determine potential relations between chemistry and biological effects.

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... Regardless, the exposure of critical life stages, such as developing fish embryos, to herbicides and other contaminants in groundwater discharge could have implications for near-term survival and long-term fish health. For example, research has linked the endocrine active properties of the chemicals investigated during this study to intersex in fishes during critical early-life stages of sexual development (Kolpin et al., 2013;Kipfer et al., 2009;Koger et al., 2000). These studies, paired with research outlining the importance of these zones of groundwater discharge to various fish species, especially during nesting and reproduction, make this interface a critical point of investigation (Brewer, 2013;Brunke and Gonser, 1997). ...
... Less is known about the environmental fate of phytoestrogens. However, studies have suggested that runoff events are a major contributor of formononetin, genistein and daidzein to aquatic environments (Kolpin et al., 2013;Wang et al., 2013). Our surface water results reinforce these findings with maximum detection of genistein, daidzein and formononetin occurring during a storm event at WBMC with concentrations of 5.8, 19 and 22 ng/L, respectively. ...
... For example, survival of larval fathead minnows was significantly reduced by environmentally relevant concentrations of phytoestrogens, including genistein and formononetin . Atrazine has also been linked to gonadal deformities in frogs exposed to concentrations of atrazine observed during this study (100 ng/L; Hayes et al., 2002), and in the Potomac River watershed, where atrazine concentrations were found to correlate with increased intersex occurrence in smallmouth bass nesting locations (Kolpin et al., 2013). Many of the contaminants investigated in this study are also considered orders of magnitude less effective as an endocrine disruptor than 17ß-estradiol (Matthews et al., 2000). ...
Article
Groundwater discharge zones in streams are important habitats for aquatic organisms. The use of discharge zones for thermal refuge and spawning by fish and other biota renders them susceptible to potential focused discharge of groundwater contamination. Currently, there is a paucity of information about discharge zones as a potential exposure pathway of chemicals to stream ecosystems. Using thermal mapping technologies to locate groundwater discharges, shallow groundwater and surface water from three rivers in the Chesapeake Bay Watershed, USA were analyzed for phytoestrogens, pesticides and their degradates, steroid hormones, sterols and bisphenol A. A Bayesian censored regression model was used to compare groundwater and surface water chemical concentrations. The most frequently detected chemicals in both ground and surface water were the phytoestrogens genistein (79%) and formononetin (55%), the herbicides metolachlor (50%) and atrazine (74%), and the sterol cholesterol (88%). There was evidence suggesting groundwater discharge zones could be a unique exposure pathway of chemicals to surface water systems, in our case, metolachlor sulfonic acid (posterior mean concentration = 150 ng/L in groundwater and 4.6 ng/L in surface water). Our study also demonstrated heterogeneity of chemical concentration in groundwater discharge zones within a stream for the phytoestrogen formononetin, the herbicides metolachlor and atrazine, and cholesterol. Results support the hypothesis that discharge zones are an important source of exposure of phytoestrogens and herbicides to aquatic organisms. To manage critical resources within the Chesapeake Bay Watershed, more work is needed to characterize exposure in discharge zones more broadly across time and space.
... For these, two extracts were combined for pesticides and another two for steroid hormones, with the last two extracts kept separate for the bioluminescent yeast estrogen screen (BLYES) assay and archival purposes. Samples for the waste indicator chemicals and the hormones were shipped to the USGS National Water Quality Laboratory (Denver, CO) for analysis using gas chromatography/mass spectrometry (GC/MS) as previously described (Kolpin et al., 2013). Analytes measured and the associated method detection limits are listed in Supp 2. Samples designated for pesticides underwent cleanup using gravity-flow Florisil® (5 g) columns prior to analysis using GC/MS (Alvarez et al., 2008). ...
... This was detected at the Swanton Dam location (Reach 3) in June of 2014. This is within the range of concentrations reported previously in the Potomac River watershed (max 71 ng/L) where intersex severity in smallmouth bass has been positively correlated with atrazine (Kolpin et al., 2013). Interestingly, correlation analysis here, independent of season, suggested a significant negative correlation between intersex severity and time-weight adjusted POCIS atrazine concentration, which is the inverse relationship previously reported in the Potomac River basin (Kolpin et al., 2013). ...
... This is within the range of concentrations reported previously in the Potomac River watershed (max 71 ng/L) where intersex severity in smallmouth bass has been positively correlated with atrazine (Kolpin et al., 2013). Interestingly, correlation analysis here, independent of season, suggested a significant negative correlation between intersex severity and time-weight adjusted POCIS atrazine concentration, which is the inverse relationship previously reported in the Potomac River basin (Kolpin et al., 2013). While this correlation was significant, the relationship was weak. ...
Article
A reconnaissance project completed in 2009 identified intersex and elevated plasma vitellogenin in male smallmouth bass inhabiting the Missisquoi River, VT. In an attempt to identify the presence and seasonality of putative endocrine disrupting chemicals or other factors associated with these observations, a comprehensive reevaluation was conducted between September 2012 and June 2014. Here, we collected smallmouth bass from three physically partitioned reaches along the river to measure biomarkers of estrogenic endocrine disruption in smallmouth bass. In addition, polar organic chemical integrative samples (POCIS) were deployed to identify specific chemicals associated with biological observations. We did not observe biological differences across reaches indicating the absence of clear point source contributions to the observation of intersex. Interestingly, intersex prevalence and severity decreased in a stepwise manner over the timespan of the project. Intersex decreased from 92.8% to 28.1%. The only significant predictor of intersex prevalence was year of capture, based on logistic regression analysis. The mixed model of fish length and year-of-capture best predicted intersex severity. Intersex severity was also significantly different across late summer and early spring collections indicating seasonal changes in this metric. Plasma vitellogenin and liver vitellogenin Aa transcript abundance in males did not indicate exposure to estrogenic endocrine disrupting chemicals at any of the four sample collections. Analysis of chemicals captured by the POCIS as well as results of screening discrete water samples or POCIS extracts did not indicate the contribution of appreciable estrogenic chemicals. It is possible that unreported changes in land-use activity have ameliorated the problem, and our observations indicate recovery. Regardless, this work clearly emphasizes that single, snap shot sampling for intersex may not yield representative data given that the manifestation of this condition within a population can change dramatically over time.
... In male fishes, concentrations of vitellogenin are naturally very low, however, when fish are exposed to EDCs they can express high vitellogenin concentrations, comparable to concentrations of female fishes (Hiramatsu et al. 2006;Lee Pow et al. 2017). Effects of EDCs such as intersex, reduced gonadal development and viability, and skewed sex ratios can therefore have detrimental effects on fish at organismal and population levels (Kolpin et al. 2013;Hillis et al. 2015;Lee Pow et al. 2017). ...
... EDCs EDC concentrations in this study were found to be markedly higher than previous studies both locally and across the region. Specifically, we found atrazine concentrations in Juniata River tributaries to be upwards of 3 times higher than previously sampled in the mainstem Juniata River, and relatively high compared to other studies across the Chesapeake Bay basin (Kolpin et al. 2013;Blazer et al. 2014;Walsh et al. 2018;Iwanowicz et al. 2019). We attribute the relatively high concentrations in this study to relative watershed size where it was previously shown in the Chesapeake Bay basin by Hall et al. (1999) that both atrazine and metolachlor concentrations were at their respective maximums at an intermediate tributary scale and at their minimums in main-stem rivers and bays. ...
... Tributaries are essential spawning and refuge habitat for juvenile SMB in late spring and early summer, and it is suggested to be the most influential time for a year class's success (Gerber and Haynes 1988;Humston et al. 2010). The timing and location of high EDC concentrations therefore poses a severe risk for juvenile life stages as it is SMB's, as well as many other fishes, most vulnerable time period (Hiramatsu et al. 2006;Kolpin et al. 2013;Walsh et al. 2018). For the current issue of Susquehanna River basin SMB decline, EDC exposure during spawning is especially important given the SMB decline has been strongest in the young-of-year, juvenile life stages (Arway and Smith 2013). ...
Article
Full-text available
The Susquehanna River basin is one of the largest and most diverse watersheds in the northeastern United States, however, its historically renowned Micropterus dolomieu (smallmouth bass-SMB) fishery has been in decline since the mid-2000s. Agricultural herbicide runoff has been identified as a major risk for Susquehanna basin SMB populations given their effects as endocrine disrupting compounds (EDCs). During the summers of 2016 and 2017, we assessed potential threats to SMB populations in 11 tributaries to the Juniata River, the second largest tributary to the Susquehanna River. Passive water samplers were installed for 38-39 days in ecologically important tributaries to quantify six common herbicides, and SMB were collected from nine sites in 2016 and 2017 to assess their health and morphology. Our passive water samplers showed markedly higher EDC concentrations than has previously been documented in the Juniata basin, with atrazine occurring at all sites and in the highest concentrations (11.09-91.02 ng/L). SMB blood samples revealed complete prevalence (100%) of vitellogenin, an egg protein precursor, in male fishes further confirming previous rates male vitellogenisis. Additionally, SMB hepatosomatic index (HSI) was statistically higher in female SMB than in male SMB (P < 0.001), and higher than many previous regional SMB studies further highlighting a contaminant-based stressor. Finally, a geometric morphometric analysis of SMB body shape indicated morphologies to be significantly site-based. Morphological differences were in line with the ram-suction feeding continuum, further revealing potential vulnerability in SMB sub-populations where EDCs may alter food web dynamics and prey availability. Overall, our study of the Juniata River Basin highlights high EDC concentrations alongside high rates of male vitellogenisis and elevated HSI, and proposes novel theory for morphological vulnerability in SMB sub-populations.
... Although atrazine application was greater than metolachlor (Table S1), stream water concentrations were similar, consistent with other data from the Potomac river basin. 83 Samples collected following herbicide application had high atrazine concentrations 23 because of the "spring flush." 84 Many organic compounds undergo chemical, physical, and biological conversions in the environment to form transformation products, as illustrated by the phosphonate herbicide glyphosate and aminomethylphosphonic acid ( Figure 3C; Figure S3A), which were detected in 45 and 57% of samples, respectively. ...
... These mobile laboratory and field observations were consistent with previous studies in SRW that reported wild fish kills, immunosuppression, intersex, and other health effects related to multiple environmental stressors, including chemical mixtures. [28][29][30]83,140 SRW has robust fish and invertebrate sampling efforts across multiple agencies to evaluate aquatic community biotic integrity ( Figure S7A). 141−145 Using the ecological integrity assessment, fewer than 10% of streams in SRW were considered to be ecologically healthy, and the fish community modified index of biotic integrity scores indicated an absence of intolerant species ( Figure S7B). ...
Article
River waters contain complex chemical mixtures derived from natural and anthropogenic sources. Aquatic organisms are exposed to the entire chemical composition of the water, resulting in potential effects at the organismal through ecosystem level. This study applied a holistic approach to assess landscape, hydrological, chemical, and biological variables. On-site mobile laboratory experiments were conducted to evaluate biological effects of exposure to chemical mixtures in the Shenandoah River Watershed. A suite of 534 inorganic and organic constituents were analyzed, of which 273 were detected. A watershed-scale accumulated wastewater model was developed to predict environmental concentrations of chemicals derived from wastewater treatment plants (WWTPs) to assess potential aquatic organism exposure for all stream reaches in the watershed. Measured and modeled concentrations generally were within a factor of 2. Ecotoxicological effects from exposure to individual components of the chemical mixture were evaluated using risk quotients (RQs) based on measured or predicted environmental concentrations and no effect concentrations or chronic toxicity threshold values. Seventy-two percent of the compounds had RQ values <0.1, indicating limited risk from individual chemicals. However, when individual RQs were aggregated into a risk index, most stream reaches receiving WWTP effluent posed potential risk to aquatic organisms from exposure to complex chemical mixtures.
... Numerous studies have attempted to establish relationships between TO and exposure to EDCs; however, the majority of these studies have failed to find strong cause-effect relationships (Reeder et al., 2005;Bjerregaard et al., 2006;Woodling et al., 2006;Douxfils et al., 2007). Only a handful of field studies have reported strong relationships between the TO prevalence and specific contaminants, such as steroids and atrazine (Iwanowicz et al., 2009;Kolpin et al., 2013). These findings were based only on field observations, so they do not necessarily imply causation. ...
... Joseph River, especially during summer months (Baldwin et al., 2016). One study reported significant positive correlations between the TO prevalence in smallmouth bass and atrazine levels (Kolpin et al., 2013). Atrazine is a well-studied endocrine disruptor that induces a wide array of adverse effects on the reproduction of aquatic organisms ( Van der Kraak et al., 2014;Richter et al., 2016;Wirbisky et al., 2016). ...
Article
Over the past decade, studies have shown that exposure to endocrine disrupting chemicals (EDCs) can cause gonadal intersex in fish. Smallmouth bass (Micropterus dolomieu) males appear to be highly susceptible to developing testicular oocytes (TO), the most prevalent form of gonadal intersex, as observed in various areas across the U.S. In this study, prevalence and severity of TO was quantified for smallmouth bass sampled from the St. Joseph River in northern Indiana, intersex biomarkers were developed, and association between TO prevalence and organic contaminants were explored. At some sites, TO prevalence reached maximum levels before decreasing significantly after the spawning season. We examined the relationship between TO presence and expression of gonadal and liver genes involved in sex differentiation and reproductive functions (esr1, esr2, foxl2, fshr, star, lhr and vtg). We found that vitellogenin (vtg) transcript levels were significantly higher in the liver of males with TO, but only when sampled during the spawning season. Further, we identified a positive correlation between plasma VTG levels and vtg transcript levels, suggesting its use as a non-destructive biomarker of TO in this species. Finally, we evaluated 43 contaminants in surface water at representative sites using passive sampling to look for contaminants with possible links to the observed TO prevalence. No quantifiable levels of estrogens or other commonly agreed upon EDCs such as the bisphenols were observed in our contaminant assessment; however, we did find high levels of herbicides as well as consistent quantifiable levels of PFOS, PFOA, and triclosan in the watershed where high TO prevalence was exhibited. Our findings suggest that the observed TO prevalence may be the result of exposures to mixtures of nonsteroidal EDCs.
... In conclusion, the Lagos lagoon ecosystem represents a major sink for many classes of contaminants such as PAHs, pesticides, insecticides, industrial chemicals, pharmaceutical and personal care product from both domestic and industrial sources of the greater Lagos metropolis. It has been demonstrated that these contaminants, notoriously produce different deleterious effects that are exerted either singularly or as mixtures, on human and wildlife physiology and fitness (Kolpin et al., 2013;Kabir et al., 2015). Among the possible types of alteration of wildlife and human physiology include chemically-induced toxicological responses, endocrine disruption and alteration of energy homeostasis, which represent a major concern in modern ecotoxicological research (Kolpin et al., 2013). ...
... It has been demonstrated that these contaminants, notoriously produce different deleterious effects that are exerted either singularly or as mixtures, on human and wildlife physiology and fitness (Kolpin et al., 2013;Kabir et al., 2015). Among the possible types of alteration of wildlife and human physiology include chemically-induced toxicological responses, endocrine disruption and alteration of energy homeostasis, which represent a major concern in modern ecotoxicological research (Kolpin et al., 2013). Therefore, our findings represent a novel ecotoxicological screening approach for evaluating the environmental quality and health of the aquatic ecosystems in Nigeria, including the Lagos lagoon. ...
Article
In this study, sediment samples from Makoko and Ikorodu sites of the Lagos lagoon (Nigeria) were screened for toxicological responses on mammalian and fish cell lines using different extraction methods. Rat hepatoma H4IIE and fish PLHC-1 cell-lines were exposed to serial dilutions of the elutriate, polar and non-polar extracts. We evaluated exposed cells for cytotoxicity and aryl hydrocarbon receptor (AhR)-mediated toxicity. Cells exposed to polar and water extracts from Makoko and Ikorodu showed viability percentage of >80% at 48 h. On the other hand, exposure to the non-polar extracts exhibited cell viability of 50-60% at all tested dilutions. For both cell lines, a significant concentration-dependent induction of cyp1a mRNA was observed after exposure to the different extracts from both sites. Interestingly, the extracts affected functional enzymes differently for both cell lines. For H4IIE cells, while EROD activity paralleled cyp1a mRNA expression patterns, MROD showed significant concentration-specific reduction in cells exposed to polar and water extracts. On the contrary, while the MROD activity paralleled cyp1a mRNA, EROD activity was significantly inhibited in PLHC-1 cells exposed to water-, polar and non-polar extracts from both sites. These observations paralleled sediments PAH contamination burden from the study sites as revealed by co-relation analysis. In conclusion, although the different extracts did not exert high cytotoxic effects (except the non-polar) at the tested concentrations, they significantly modulated phase I biotransformation responses, showing that the studied sediments contain complex chemical mixture in the different extracts, with potential for overt physiological and general health consequences.
... In the aquatic environments of human-impacted regions, fish are continually exposed to mixtures of hundreds and more likely thousands of chemicals which enter the aquatic environment from a variety of industrial, domestic, and agricultural sources (Kolpin et al. 2013;Moschet et al. 2014;Viganò et al. 2015a). Most of these chemicals are present at low and very low concentrations and although only a fraction is generally bioavailable, complex mixture effects have been observed in aquatic organisms, both for waterborne and sediment-bound chemicals (Escher et al. 2013;Nowell et al. 2013;Garcia-Käufer et al. 2015;Zhang et al. 2015a). ...
... This is often common in regulatory approaches, which typically focus on a limited number of chemicals of priority interest, as is the case, for example, in the European Water Framework Directive (WFD) (EC 2013;and Watch list 2015). As a result, it is unlikely that chemical-specific approaches can ensure a satisfactory water quality assessment of impacted systems (underestimation of contaminant mixture), or prevent that mixtures of unknown chemicals may pose a risk to aquatic organisms (Escher et al. 2013;Kolpin et al. 2013;Moschet et al. 2014). In this respect, endocrine active chemicals have raised much concern since they can be effective at very low concentrations, and when in mixtures, also at levels which individually have no effects (Brian et al. 2007;Duong et al. 2010;Wu et al. 2014a). ...
Article
Full-text available
Sediment toxicity plays a fundamental role in the health of inland fish communities; however, the assessment of the hazard potential of contaminated sediments is not a common objective in environmental diagnostics or remediation. This study examined the potential of transcriptional endpoints investigated in zebrafish (Danio rerio) exposed to riverbed sediments in ecotoxicity testing. Embryo-larval 10-day tests were conducted on sediment samples collected from five sites (one upstream and four downstream of the city of Milan) along a polluted tributary of the Po River, the Lambro River. Sediment chemistry showed a progressive downstream deterioration in river quality, so that the final sampling site showed up to eight times higher concentrations of, for example, triclosan, galaxolide, PAH, PCB, BPA, Ni, and Pb, compared with the uppermost site. The embryo/larval tests showed widespread toxicity although the middle river sections evidenced worse effects, as evidenced by delayed embryo development, hatching rate, larval survival, and growth. At the mRNA transcript level, the genes encoding biotransformation enzymes (cyp1a, gst, ugt) showed increasing upregulations after exposure to sediment from further downstream sites. The genes involved in antioxidant responses (sod, gpx) suggested that more critical conditions may be present at downstream sites, but even upstream of Milan there seemed to be some level of oxidative stress. Indirect evidences of potential apoptotic activity (bcl2/bax < 1) in turn suggested the possibility of genotoxic effects. The genes encoding for estrogen receptors (erα, erβ1, erβ2) showed exposure to (xeno)estrogens with a progressive increase after exposure to sediments from downstream sites, paralleled by a corresponding downregulation of the ar gene, likely related to antiandrogenic compounds. Multiple levels of thyroid disruption were also evident particularly in downstream zebrafish, as for thyroid growth (nkx2.1), hormone synthesis and transport (tg, ttr, d2), and signal transduction (trα, trβ). The inhibition of the igf2 gene reasonably reflected larval growth inhibitions. Although none of the sediment chemicals could singly explain fish responses, principal component analysis suggested a good correlation between gene transcripts and the overall trend of contamination. Thus, the combined impacts from known and unknown covarying chemicals were proposed as the most probable explanation of fish responses. In summary, transcriptional endpoints applied to zebrafish embryo/larval test can provide sensitive, comprehensive, and timeliness information which may greatly enable the assessment of the hazard potential of sediments to fish, complementing morphological endpoints and being potentially predictive of longer studies.
... Although, the risk of these contaminants to aquatic life is still uncertain, there is concern that exposure to contaminants and contaminant mixtures may have negative populationlevel effects on some fisheries (Hamilton et al., 2016;Martin and Grant, 2019). For example, starting in the early 2000's, there have been signs of reproductive endocrine disruption, clinical signs of disease, declines in catch rates and mortality events in smallmouth bass (Micropterus dolomieu) populations (Arway and Smith, 2013;Kolpin et al., 2013;Blazer et al., 2014;Smith et al., 2015;Schall et al., 2018;Walsh et al., 2018). Over this same time period, several studies detected chemicals in surface waters that could represent a risk to aquatic biota. ...
... We were particularly interested in the presence of chemical contaminants within the context of the observed health issues and declines in abundance of smallmouth bass populations documented in several rivers within the Chesapeake Bay Watershed, recognizing that not only contaminant occurrence but also contaminant concentrations are important. Recent studies suggest that these potential reproductive health issues may be due to exposure to endocrine disrupting compounds (often hormones) present in surface water (Blazer et al., 2012Kolpin et al., 2013). The presence of endocrine disrupting compounds can be captured through the measurement of total estrogenicity, a measurement of estrogenic activity in water (Routledge and Sumpter, 1996;Balsiger et al., 2010;Baldigo et al., 2014). ...
Article
Investigating the spatiotemporal dynamics of contaminants in surface water is crucial to better understand how introduced chemicals are interacting with and potentially influencing aquatic organisms and environments. Within the Chesapeake Bay Watershed, United States, there are concerns about the potential role of contaminant exposure on fish health. Evidence suggests that exposure to contaminants in surface water is causing immunosuppression and intersex in freshwater fish species. Despite these concerns, there is a paucity of information regarding the complex dynamics of contaminant occurrence and co-occurrence in surface water across both space and time. To address these concerns, we applied a Bayesian hierarchical joint-contaminant model to describe the occurrence and co-occurrence patterns of 28 contaminants and total estrogenicity across six river sites and over three years. We found that seasonal occurrence patterns varied by contaminant, with the highest occurrence probabilities during the spring and summer months. Additionally, we found that the proportion of agricultural landcover in the immediate catchment, as well as stream discharge, did not have a significant effect on the occurrence probabilities of most compounds. Four pesticides (atrazine, metolachlor, fipronil and simazine) co-occurred across sites after accounting for environmental covariates. These results provide baseline information on the contaminant occurrence patterns of several classes of compounds within the Chesapeake Bay Watershed. Understanding the spatiotemporal dynamics of contaminants in surface water is the first step in investigating the effects of contaminant exposure on fisheries and aquatic environments.
... The insecticide methoxyfenozide had site-detection frequencies of 93 and 1% in POCIS and water samples, respectively. These examples highlight an advantage of using an integrative sampler, in that the mass of a chemical accumulated in the POCIS over time was sufficient to satisfy the method detection limits of the instrument, whereas the concentration in a discrete water sample was less than the instrument's detection capability (Alvarez et al., 2005;Kolpin et al., 2013). Conversely, a few compounds were frequently detected in water but rarely in POCIS, including the atrazine degradate didealkylatrazine (99 and 14%, respectively) and the fungicide pyraclostrobin (72 and 5%, respectively). ...
... Bayen et al. (2014) reported good correlations (approximately 1:1) between concentrations in POCIS and mean concentrations in filtered grab samples for chemical contaminants, including pesticides and pharmaceuticals, in tropical waters. Other studies have focused on comparing detections, rather than concentrations, between POCIS results and water samples (Alvarez et al., 2005;Kolpin et al., 2013). In these studies, there often was a high degree of variability in the presence and measured concentration of chemicals in the water samples relative to the presence of chemicals in the POCIS, which is similar to the variability observed in the MSQA study presented here. ...
Article
Full-text available
The Midwest United States is an intensely agricultural region where pesticides in streams pose risks to aquatic biota, but temporal variability in pesticide concentrations makes characterization of their exposure to organisms challenging. To compensate for the effects of temporal variability, we deployed polar organic chemical integrative samplers (POCIS) in 100 small streams across the Midwest for about 5 weeks during summer 2013 and analyzed the extracts for 227 pesticide compounds. Analysis of water samples collected weekly for pesticides during POCIS deployment allowed for comparison of POCIS results with periodic water-sampling results. The median number of pesticides detected in POCIS extracts was 62, and 141 compounds were detected at least once, indicating a high level of pesticide contamination of streams in the region. Sixty-five of the 141 compounds detected were pesticide degradates. Mean water concentrations estimated using published POCIS sampling rates strongly correlated with means of weekly water samples collected concurrently, however, the POCIS-estimated concentrations generally were lower than the measured water concentrations. Summed herbicide concentrations (units of ng/POCIS) were greater at agricultural sites than at urban sites but summed concentrations of insecticides and fungicides were greater at urban sites. Consistent with these differences, summed concentrations of herbicides correlate to percent cultivated crops in the watersheds and summed concentrations of insecticides and fungicides correlate to percent urban land use. With the exception of malathion concentrations at nine sites, POCIS-estimated water concentrations of pesticides were lower than aquatic-life benchmarks. The POCIS provide an alternative approach to traditional water sampling for characterizing chronic exposure to pesticides in streams across the Midwest region.
... Increased rates of chronic mortality and co-infections of bacterial, viral, and/or parasitic pathogens within both adult and young-of-year (YOY) fish may be indicative of immunosuppression (Smith et al., 2015;Starliper et al., 2013;Walsh et al., 2018). SMB, an indicator species, are extremely sensitive to environmental changes, and previous analyses of water, sediment, and fish tissues have identified the presence of varying levels of environmental contaminants capable of inducing endocrine disruption and immunosuppression Kolpin et al., 2013;McClure et al., 2020;Walsh et al., 2018). The majority of previous studies have focused on adult SMB and the identification of estrogenic compounds in surface waters through targeted analyses. ...
... Targeted analyses are an ideal approach when contaminants are known or suspected to be in an area. In developed communities, it is possible to predict which chemical contaminants will be present at a site based on the land use around the area (e.g., farmland, manufacturing complexes, or wastewater treatment plants) (Furihata et al., 2019;Kolpin et al., 2013). However, target compounds are not always detected and those that are may not correlate with the observed health impairments, such as intersex and immunosuppression in SMB. ...
Article
Smallmouth bass in the Susquehanna River Basin, Chesapeake Bay Watershed, USA, have been exhibiting clinical signs of disease and reproductive endocrine disruption (e.g., intersex, male plasma vitellogenin) for over fifteen years. Previous histological and targeted chemical analyses have identified infectious agents and pollutants in fish tissues including organic contaminants, mercury, and perfluorinated compounds, but a common causative link for the observed signs of disease across this widespread area has not been determined. This study examines 146 young-of-year smallmouth bass collected from 14 sampling sites in the Susquehanna River Basin, Pennsylvania, USA with varying levels of disease prevalence. Whole fish were extracted by a recently developed modification to the quick, easy, cheap, effective, rugged, and safe extraction method and analyzed by comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry. A targeted analysis was conducted to identify the presence and quantity of 127 known contaminants, including polychlorinated biphenyls, brominated diphenyl ethers, organochlorinated pesticides, and pharmaceutical and personal care products. A non-targeted analysis was conducted on the same data set to identify analytes of interest not included on routine target compound lists. Chromatographic alignment through Statistical Compare (ChromaTOF GC) was followed by Fisher ratio and principal component analysis to reduce the data set from thousands of peaks per sample to a final data set of 65 analytes of interest. Comparisons of these 65 compounds between Normal (no observed health anomalies) and Lesioned (observed health anomaly at time of collection) fish revealed increased levels of three chemical families in Lesioned fish including esters, ketones, and nitrogen containing compounds.
... The presence of these pharmaceuticals poses many risks on the aquatic environment. The U.S Geological Survey, for instance, discovered intersex fish in the Potomac River due to estrogen contamination [7]. In this context, another study realized by researchers in Canada detected 25 antibiotics in drinking water in small concentrations [8]. ...
Article
Full-text available
A massive volume of expired medications amasses annually around the world because of pharmaceutical overprescription, combined with overproduction. The accumulation of pharmaceutical waste imposes ecological, economic and social/ethical burdens. Managing this presumed “waste” has developed into a global challenge due to the absence of specific regulations, unreasonable behavior of the patients, and an improper understanding of the concept of “expired medications” in general. This paper summaries, first, the recent literature reporting practices related to the disposal of unused medications. In this context, 48 papers from 34 countries with a total of 33,832 participants point towards a significant lack of public awareness regarding the appropriate disposal of such biologically potent chemicals. These findings are corroborated by a local survey on the disposal practices of unused medicines among pharmacy students at Saarland University. The regulatory aspects surrounding this topic, often based on the official guidelines for the disposal of expired medications and local waste management strategies, are then discussed in light of these findings. Finally, a closer inspection of the epistemic values of expired medications and different strategies for managing expired medications have been reviewed.
... The presence of emerging contaminants (ECs) in the environment has become a significant concern in recent years, especially in sensitive aquatic ecosystems. Many ECs, such as natural and synthetic estrogens, are known to be relatively widespread in surface water bodies (DeLaune and Moore, 2013;Finlay-Moore et al., 2000;Gall et al., 2011;Goeppert et al., 2014;Kjaer et al., 2007;Kolpin et al., 2013;Nie et al., 2015;van Donk et al., 2013), given their presence in municipal wastewater effluent (Andaluri et al., 2012;Desbrow et al., 1998;Nakada et al., 2004;Ternes et al., 1999;Ying et al., 2002). Conventional wastewater treatment processes were not designed to remove estrogens and other ECs, and therefore wastewater effluent discharged to receiving water bodies is an important pathway of estrogens into the environment (Chang et al., 2011;Pal et al., 2010;Ying et al., 2009). ...
Article
Planned beneficial re-use of water has become an increasingly common conservation practice worldwide, sparking questions about the degree of water treatment needed to mitigate negative environmental impacts. Since the early 1980s, as an alternative to surface discharge, the Pennsylvania State University has spray-irrigated all of its treated wastewater effluent via land application onto an environmental setting known as the "Living Filter" site (∼245 ha). The impacts of spray irrigation on nearby ephemeral wetlands, known as vernal pools, were explored. The pools gain water from both natural rainfall and spray-irrigation of the University's treated wastewater. The occurrence and persistence of estrogens in three vernal pools were quantified by analyzing > 137 water samples collected from the pools over an eight-week period coincident with the development period of native amphibian larvae. Additionally, dissolved oxygen, oxidation-reduction potential, water level, water temperature, electrical conductivity, pH, and rainfall data were measured continuously throughout the study period within each pool. Further, the treated wastewater effluent was sampled during each weekly spray-irrigation event. Estrone was detected in nearly 100% of the vernal pool samples, with concentrations up to 6.2 ng L −1. Additionally, 17α-estradiol was not detected in the wastewater effluent, but was present in 52% of the vernal pool samples. 17β-estradiol, estriol, and 17α-ethinylestradiol were detected in fewer than 10% of the vernal pool samples. The findings of this research have important implications for management practices that can help protect these critical habitats.
... For instance, the detection of the insect repellent DEET in wastewater is commonly attributed to the dermal application of the molecule which is subsequently washed from the skin when showering and collected by the sewer system. However, the common detection of DEET in wastewater during the winter period, in dry areas that are not associated with the abundance of mosquitoes, together with the detection of the insect repellent in blank samples (Anumol et al., 2013;Kolpin et al., 2013;Wode et al., 2015) has led to suspect the occurrence of potential analytical interferences or an uncharacterized source of DEET (Merel et al., 2015b;Merel and Snyder, 2016). Similarly, recent studies using targeted analysis to monitor biocides identified households and paper production industries as previously unknown sources of the fungicide carbendazim in wastewater and the environment (Bollmann et al., 2014;Merel et al., 2018;Singer et al., 2010). ...
Article
Wastewater is a significant environmental and public health concern which management is a constant challenge since antiquity. Wastewater research has increased exponentially over the last decades. This paper provides a global overview of the exponentially increasing wastewater research in order to identify current challenges and paradigm shifts. Besides households, hospitals and typical industries, other sources of wastewater appear due to emerging activities like hydraulic fracturing. While the composition of wastewater needs constant reassessment to identify contaminants of interest, the comprehensive chemical and toxicological analysis remains one of the main challenges in wastewater research. Moreover, recent changes in the public perception of wastewater has led to several paradigm shifts: i) water reuse considering wastewater as a water resource rather than a hazardous waste, ii) wastewater-based epidemiology considering wastewater as a source of information regarding the overall health of a population through the analysis of specific biomarkers, iii) circular economy through the implementation of treatment processes aiming at harvesting valuable components such as precious metals or producing valuable goods such as biofuel. However, wastewater research should also address social challenges such as the public acceptance of water reuse or the access to basic sanitation that is not available for nearly a third of the world population.
... Fish with disrupted sexual development, specically feminized male sh, have been found in numerous rivers. [9][10][11][12] More importantly, since surface water is a major source of drinking water, human exposure to EDCs will likely occur because some of these contaminants are not effectively removed during drinking water treatment. 13 In the past decade, many compounds have been detected in various surface/source waters with evidence of endocrine disrupting effects from sub ng L À1 to mg L À1 levels. ...
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The occurrence of endocrine disrupting chemicals (EDCs) in aquatic environments has been of long concern because of their threat to human and aquatic health. Liquid chromatography coupled with tandem mass...
... In his recent studies, he analyzed the chemicals contaminants' spatial and temporal variations and exposures to fish (e.g. smallmouth bass), livestock and human health [54][55][56][57][58][59][60][61][62][63][64]. The impact of agricultural chemical inputs on environment: global evidence from informetrics analysis and visualization Our findings suggest that the three stages identified (i.e. ...
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This paper identifies and analyzes salient research frontiers, research hotspots and high-frequency terms using aggregated and multiple-source literature records related to the topic of 'effects of agricultural chemical inputs on the environment.' We employ a set of Informetrics Theory methods (i.e. document co-citation analysis, document clustering and co-words analysis via co-occurrence network of subject terms) for our analysis. Our findings suggest that in the past 30 years, research about this topic can be divided into three stages, namely the early stage (1990-99), the middle stage (2000-07) and the late stage (2008-16). Research directions for the three identified stages deal primarily with (a) the effects of pesticides and veterinary drugs on the environment, (b) the influence of fertilizer application on the environment and food safety and (c) the technologies and strategies to monitor and control the impact of agricultural chemical inputs on the environment. Particularly, we find that research in the topic of interest primarily focusses on agricultural scenarios of food crop production and fish farming. In terms of agricultural chemical inputs, major attention is given to pesticides and fertilizers. With respect to the impact of agricultural inputs, pollutant formation and transferring process, nitrogen and phosphorous cycles, impact assessment indicators, as well as pollution prevention and reduction strategies are the most researched areas, and soil and water constitute the main researched environmental media. Finally, institutions and organization based in North America, East Asia and Europe are main research contributors on this topic.
... Toxic chemical contaminants enter the Chesapeake Bay through numerous pathways from legacy sediments to direct runoff and precipitation. In recent years, concerns have risen over chemical contaminants associated with pharmaceuticals and personal care products that reach waters through sewage systems and are believed to be involved in disrupting the reproductive systems of fish and wildlife (Chen et al., 2010;Kolpin et al., 2013). ...
... In summary, the aquatic environment represents a major sink for many classes of contaminants such as pesticides, insecticides, industrial chemicals, pharmaceutical and personal care product. These contaminants are notoriously known for different deleterious effects that are exerted either singularly or as mixtures, on human and wildlife physiology and fitness (Kolpin et al., 2013). Among the possible types of alteration of wildlife and human physiology include chemically-induced endocrine disruption, which represents a major concern in modern ecotoxicological research (Kabir et al., 2015;Scholz and Mayer, 2008). ...
Article
In the present study, H295R human cells were used to investigate the endocrine disruptor potential of three different sediments extracts taken from a Nigerian tropical freshwater dam (Awba Dam), using three extraction methods that allowed a selective consideration of contaminants based on their binding affinity, which is mainly driven by polarity, to sediment particles. After exposure to different concentration of each extract, H295R cells were evaluated for the expression profiles of 10 steroidogenic enzyme genes and estradiol (E2) and testosterone (T) levels. Our results showed a comparable concentrated-related increase in the expression of 17βhsd1, 3βhsd2 and cyp21 in cells treated with the polar and non-polar extracts. The star, hmgr, cyp11b2 and 17β-hsd4 were slightly decreased, in an apparent concentration-specific manner, after treatment with the polar extract and decreased in the non-polar treatment. The cyp11a and cyp17 showed an opposite trend in the polar and non-polar treatments. E2 was significantly higher in cell treated with the non-polar extract. Elutriate exposure produced less pronounced variation in mRNA and hormones levels. Overall the extract with non-polar compounds produced the most severe effects in H295R cells. Thus, direct ingestion of detritus and mud from fishes and other benthonic organisms represent possible transfer of contaminants in the trophic web, and mainly account for alteration of the endocrine system previously observed in fish from the same study site.
... Co-infections of bacterial, viral, as well as parasitic infections have been associated with these events [4,6,7] suggesting immunosuppression. Estrogenic endocrine disruption as evidenced by testicular oocytes (intersex), vitellogenin in male fish [8][9][10] and the occurrence of contaminants linked to intersex [4,7,11,12] has been confirmed within the areas of the Chesapeake watershed where disease events occur. The observation of a complex disease etiology that includes multiple obligate and opportunistic pathogens and parasites as well as endocrine disruption necessitates laboratory investigations into the potential changes in physiologic functions including the immune response. ...
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Smallmouth bass (Micropterus dolomieu) are used as an indicator species in environmental monitoring and assessment studies. However, laboratory-based studies for methods development and effector assessment are limited for this species. Nutrition, a known modulator of teleost physiological responses including immune function, is a critical knowledge-gap sometimes overlooked in the design of laboratory studies. We report the results from a study evaluating a commercially available artificial pelleted diet for bass and live feed (fathead minnows). Following a six-month diet-acclimation period, age-0 smallmouth bass were assessed using morphometric measures, histologic and immune-function end points using conventional methods, miniaturized cell isolation and assay methods as well as imaging flow cytometry. Fish on the two diets did not significantly differ in length, weight, or condition factor, indicating that growth was similar in the two groups. Histologic examination revealed relatively higher levels of macrophage aggregates and accumulation of ceroid/lipofuscin in the spleen as well as hepatocyte changes in the pellet-fed group. Leukocytes from the pellet-fed group exhibited significantly elevated bactericidal activity and significantly depressed mitogen response compared to fish fed live feed. Following exposure to a known inducer of inflammatory responses, bacterial lipopolysaccharide, responses including the transition of leukocytes to an apoptotic/necrotic condition differed significantly based on diet. Histologic findings were consistent with the occurrence of diet-related oxidative stress in the pellet-fed fish. Oxidative stress can be induced by multiple factors including environmental pollutants. For a diet to be useful in laboratory-based studies, it cannot elicit response that could also be induced by experimental treatments. To do so greatly complicates the detection of experimental effects. Until an artificial diet is developed for smallmouth bass that does not produce potentially confounding conditions for laboratory-based studies, use of a live feed appears to be the best option.
... These variable correlations indicate that the correlations may not be causal in nature. The variable association between endpoints and chemical classes is similar to those reported in other studies; such as in Bizarro et al. (2014) where the authors also noted variable correlations or in Kolpin et al. (2013) where only limited correlations between chemical and biological results were apparent. This is not surprising considering aquatic biota are exposed to many contaminants and other physico-chemical stressors, such as those measured in this study as well as those that could be present but were not analyzed for, and these mixtures can have combination effects. ...
Article
The Laurentian Great Lakes are a valuable natural resource that is affected by contaminants of emerging concern (CECs), including sex steroid hormones, personal care products, pharmaceuticals, industrial chemicals, and new generation pesticides. However, little is known about the fate and biological effects of CECs in tributaries to the Great Lakes. In the current study, 16 sites on three rivers in the Great Lakes basin (Fox, Cuyahoga, and Raquette Rivers) were assessed for CEC presence using polar organic chemical integrative samplers (POCIS) and grab water samplers. Biological activity was assessed through a combination of in vitro bioassays (focused on estrogenic activity) and in vivo assays with larval fathead minnows. In addition, resident sunfish, largemouth bass, and white suckers were assessed for changes in biological endpoints associated with CEC exposure. CECs were present in all water samples and POCIS extracts. A total of 111 and 97 chemicals were detected in at least one water sample and POCIS extract, respectively. Known estrogenic chemicals were detected in water samples at all 16 sites and in POCIS extracts at 13 sites. Most sites elicited estrogenic activity in bioassays. Ranking sites and rivers based on water chemistry, POCIS chemistry, or total in vitro estrogenicity produced comparable patterns with the Cuyahoga River ranking as most and the Raquette River as least affected by CECs. Changes in biological responses grouped according to physiological processes, and differed between species but not sex. The Fox and Cuyahoga Rivers often had significantly different patterns in biological response Our study supports the need for multiple lines of evidence and provides a framework to assess CEC presence and effects in fish in the Laurentian Great Lakes basin.
... The application of screening and TWA determination allows for the evaluation of spatial and temporal distribution in aquatic environments (Morin et al., 2012;Söderström et al., 2009). The ability of the POCIS to screen pollutants was also shown in a study conducted by Kolpin et al. (2013) where POCIS were used to determine the exposure of chemical contaminants to smallmouth bass in the Potomac River basin. Among the chemical contaminants tylosin, sulfamethazine, and atrazine detection frequencies were 0, 40, and 100% respectively. ...
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This study evaluated the influence of temporal variation on the occurrence, fate, and transport of tylosin (TYL) and sulfamethazine (SMZ); antibiotics commonly used in swine production. Atrazine (ATZ) was used as a reference analyte to indicate the agricultural origin of the antibiotics. We also assessed the impact of season and hydrology on antibiotic concentrations. A reconnaissance study of the South Fork watershed of the Iowa River (SFIR), was conducted from 2013 to 2015. Tile drain effluent and surface water were monitored using polar organic integrative sampler (POCIS) technology. Approximately 169 animal feeding operations (AFOs) exist in SFIR, with 153 of them being swine facilities. All analytes were detected, and detection frequencies ranged from 69 to 100% showing the persistence in the watershed. Antibiotics were detected at a higher frequency using POCIS compared to grab samples. We observed statistically significant seasonal trends for SMZ and ATZ concentrations during growing and harvest seasons. Time weighted average (TWA) concentrations quantified from the POCIS were 1.87ngL(-1) (SMZ), 0.30ngL(-1) (TYL), and 754.2ngL(-1) (ATZ) in the watershed. SMZ and TYL concentrations were lower than the minimum inhibitory concentrations (MIC) for E. coli. All analytes were detected in tile drain effluent, confirming tile drainage as a pathway for antibiotic transport. Our results identify the episodic occurrence of antibiotics, and highlights the importance identifying seasonal fate and occurrence of these analytes.
... Concentrations of herbicides (primarily those associated with row-crop production, including atrazine, its degradate deethylatrazine, and metolachlor) in discrete water samples correlated with TO prevalence and severity. There was also correlation with biogenic hormones plus plant sterols in the sediment associated with bass nests, and total estrogenicity, atrazine, and organochlorine concentrations in extracts from passive integrated water samplers (Kolpin et al., 2013). It was hypothesized that factors associated with agricultural runoff may be responsible for induction of the intersex (and/or sensitivity to estrogenic chemicals) in early life stages, while factors from multiple sources, including point sources such as WWTP, may increase the severity in adults. ...
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The Chesapeake Bay is the largest estuary in the United States and its watershed includes river drainages in six states and the District of Columbia. Sportfishing is of major economic interest, however, the rivers within the watershed provide numerous other ecological, recreational, cultural and economic benefits, as well as serving as a drinking water source for millions of people. Consequently, major fish kills and the subsequent finding of estrogenic endocrine disruption (intersex or testicular oocytes and plasma vitellogenin in male fishes) raised public and management concerns. Studies have occurred at various sites within the Bay watershed to document the extent and severity of endocrine disruption, identify risk factors and document temporal and spatial variability. Data from these focal studies, which began in 2004, were used in CART (classification and regression trees) analyses to better identify land use associations and potential management practices that influence estrogenic endocrine disruption. These analyses emphasized the importance of scale (immediate versus upstream catchment) and the complex mixtures of stressors which can contribute to surface water estrogenicity and the associated adverse effects of exposure. Both agricultural (percent cultivated, pesticide application, phytoestrogen cover crops) and developed (population density, road density, impervious surface) land cover showed positive relationships to estrogenic indicators, while percent forest and shrubs generally had a negative association. The findings can serve as a baseline for assessing ongoing restoration and management practices.
... Concentrations of herbicides (primarily those associated with row-crop production, including atrazine, its degradate deethylatrazine, and metolachlor) in discrete water samples correlated with TO prevalence and severity. There was also correlation with biogenic hormones plus plant sterols in the sediment associated with bass nests, and total estrogenicity, atrazine, and organochlorine concentrations in extracts from passive integrated water samplers (Kolpin et al., 2013). It was hypothesized that factors associated with agricultural runoff may be responsible for induction of the intersex (and/or sensitivity to estrogenic chemicals) in early life stages, while factors from multiple sources, including point sources such as WWTP, may increase the severity in adults. ...
Article
Ecological risk assessments play an important role in environmental management and decision-making. Although empirical measurements of the effects of habitat changes and chemical exposure are often made at molecular and individual levels, environmental decision-making often requires the quantification of management-relevant, population-level outcomes. In this study, we generalized a modeling framework to evaluate population-level ecological risk of environmental stress and bioactive chemicals. The modeling framework includes (1) a biological model module that incorporates complex and interacting biological and ecological processes, and environmental stochasticity, (2) an effect module that links the impacts of environmental changes and chemical exposure to individual characteristics, and (3) a population module that makes decisions on the choice of population-level properties to best capture the effects and thus to track in the model based on the target species and the research and management interest. This framework is a 3-module procedure that provides an alternative way for researchers to organize, present and communicate the risk assessment modeling studies. To demonstrate this framework, we used a socioeconomically important riverine fish species, smallmouth bass Micropterus dolomieu, as the model species. We developed an individual-based model as the biological model module. We evaluated the impacts of changing water temperature and flow regimes, and the impacts of exposure to estrogenic endocrine disrupting compounds (EEDC) on smallmouth bass populations in the Chesapeake Bay Watershed, USA. Warm summer water temperatures and year-round high flows had the most severe impacts on the smallmouth bass population. An increase in exposure level to EEDC, both year-round and in summer months, substantially reduced population size, spawner and recruit abundance, and the proportion of quality-length individuals. Acute exposure to EEDC was more detrimental to the population than chronic exposure. Acute exposure during spawning season had the most severe impacts. This modeling framework can be extended to other species, environmental factors and chemicals, and can be used to inform management and conservation decisions.
... Nutrient control is a priority focus within the Chesapeake Bay Watershed (CBW) given observed impacts on biological communities and recreational opportunities (Butt and Brown, 2000). Moreover, the presence of estrogenic endocrine-disrupting chemicals (EEDCs) and evidence of endocrine disruption in fishes of the CBW has been a concern of resource managers and the public (Blazer et al., 2007;Blazer et al., 2012;Kolpin et al., 2013). Currently, there are multiple strategies implemented to reduce watershed nutrient loads in streams through municipal wastewater treatment plant (WWTP) upgrades, overflows of combined sewer system (CSOs) replacement and nonpoint source best management practices (BMPs). ...
Article
We evaluate the impacts of different nutrient management strategies on the potential for co-managing estrogens and nutrients in environmental waters of the Potomac watershed of the Chesapeake Bay. These potential co-management approaches represent agricultural and urban runoff, wastewater treatment plant effluent, and combined sewer overflow replacements. Twelve estrogenic compounds and their metabolites were analysed by gas chromatography–mass spectrometry. Estrogenic activity (E2Eq) was measured by in vitro bioassay. We detected estrone E1 (0.05–6.97 ng L⁻¹) and estriol E3 (below detection-8.13 ng L⁻¹) and one conjugated estrogen (estrone-3-sulfate E1-3S; below detection-8.13 ng L⁻¹). E1 was widely distributed and positively correlated with E2Eq, water temperature, and dissolved organic carbon (DOC). Among nonpoint sources, E2Eq, and concentrations of E1, soluble reactive phosphorus (SRP) and total dissolved nitrogen (TDN) decreased by 51–61%, 77–82%, 62–64%, 4–16% in restored urban and agricultural streams with best management practices (BMPs) relative to unrestored streams without BMPs. In a wastewater treatment plant (Blue Plains WWTP), >94% of E1, E1-3S, E3, E2Eq and TDN were removed while SRP increased by 305% during nitrification/denitrification as a part of advanced wastewater treatment. Consequently, E1 and TDN concentrations in WWTP effluents were comparable or even lower than those observed in the receiving stream or river waters, and the effects of wastewater discharges on downstream E1 and TDN concentrations were minor. Highest E2Eq value and concentrations of E1, E3, and TDN were detected in combined sewer overflow (CSO). This study suggests that WWTP upgrades with biological nutrient removal, CSO management, and certain agricultural and urban BMPs for nutrient controls have the potential to remove estrogens from point and nonpoint sources along with other contaminants in streams and rivers.
... The non-tidal portion of Potomac River flows through different land use zones that range from agricultural in Fredrick (Maryland), suburban in Germantown (Maryland), and urban in Washington DC, thus monitoring the quality of water in Potomac River is highly important. Previous studies on micropollutants in Potomac River have focused on the determination of estrogenic contaminants such as estrogen and estradiol and their relationship to the high prevalence of male fish intersex observed in the river (Young et al., 2014;Kolpin et al., 2013). Other studies have detected polychlorinated biphenyls, polybrominated diphenyl ethers, and PFASs from Ospreys nesting in Chesapeake Bay (Rattner et al., 2004) which are known for their high persistence in the environment and high bioaccumulation potential in organisms (Krafft and Riess, 2015). ...
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The Publisher regrets that this article is an accidental duplication of a published article, http://dx.doi.org/10.1016/j.wroa.2021.100088. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.
... Based on established evidence of ubiquitous, transboundary atmospheric transport, and deposition capabilities, photo-stability, ecological risk, and human health concerns, PBDEs are grouped as persistent organic pollutants (Peverly et al., 2015;Sohail et al., 2017;Bai et al., 2018;Chakraborty et al., 2018;O'Brien et al., 2019). Environmental PBDEs are associated with cumulative and deleterious effects to soilbiota health, consumption of PBDEs contaminated food, human, and animal exposure through accidental; oral, dermal, and inhalation contacts (Assis et al., 2012;Kolpin et al., 2013;Harmouche-Karaki et al., 2019). PBDE health hazards are associated with liver damage, neurobehavioral disorders cancer, allergies, birth defects, and hypersensitivity. ...
Article
The usage of polybrominated diphenyl ethers (PBDEs) as fire-resistant additives was banned several years ago; however, they persist in several environmental compartments. This study determined the concentrations and associated exposure risks of Ʃ39PBDEs in soil depth samples from selected metals and plastics scrap catchments in the Niger Delta region, Nigeria. Samples extraction was performed by the Soxhlet extraction method followed by GC-MS analysis. The mean concentrations of ∑39PBDEs-congeners ranged from 0.01 ± 001 to 25 ± 11.0 ng g⁻¹ in the topsoil and 0.01 ± 0.01 to 6.50 ± 4.7 ng g⁻¹ in the subsoil. The PBDE homologue profiles were dominated by di, penta, hexa, and tri-BDEs. The PBDEs cancer and non-cancer risk for infants were higher than those in adults, expressed in the following order: ingestion > dermal contact > inhalation. In general, the sum for the three exposure pathways was within the allowable threshold limit, suggesting a low lifetime cancer risk from soil exposures. The technical mixture used for paints, plastics, hydraulic, and dielectric insulating fluids for transformers, capacitors, cable wires, and power capacitors is a potential source of Ʃ39PBDEs in the study area. With the increase in metals scrap enterprise in Nigeria, this study provides empirical data useful for the development of efficient strategies to strengthen and enforce existing regulations for metals and plastics scrap land use in Nigeria and other similar catchments around the world.
... The same study also found evidence supporting a potential association between bass TOs and measurements of a known estrogenic compound, citing significant correlations between water concentrations of estrone and TO prevalence, TO severity, and the percentage of male bass detected with plasma Vtg [29]. A companion study conducted at the same sites also found significant correlations between TOs and sediment concentrations of 2 estrogenic sterols, but not estrone [30]. The potential contributions from nonpoint sources add uncertainty to the likelihood that fish from any particular site might have been exposed to EDCs, and may be responsible for some of these incongruences. ...
Article
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Testicular oocytes (TOs) have been found in black basses (Micropterus spp.) from many locations in North America. The presence of TOs is often assumed to imply exposure to estrogenic endocrine disrupting compounds (EDCs), however, a definitive causal relationship has yet to be established, and TO prevalence is not consistently low in fish from areas lacking evident EDC sources. This might indicate any of a number of situations: (a) unknown or unidentified EDCs or EDC sources, (b) induction of TOs by other stressors, or (c) TOs occurring spontaneously during normal development. In the present study we analyzed TO occurrence in smallmouth bass (M. dolomieu) from eight populations in Northeastern Minnesota watersheds with differing degrees of human development and hence, presumed likelihood of exposure to anthropogenic chemicals. Three watersheds were categorized as moderately developed, based on the presence of municipal wastewater discharges and higher human population density (4-81 per km2), and five watersheds were minimally developed, with very low human population density (0-1 per km2) and minimal built environment. Testicular tissues from mature fish were evaluated using a semi-quantitative method that estimated TO density, normalized by cross-sectional area. TO prevalence and density among populations from moderately developed watersheds was higher than in populations from minimally developed watersheds. However, TO prevalence was unexpectedly high and variable (7-43%) in some populations from minimally developed watersheds, and only weak evidence was found for a relationship between TO density and watershed development, suggesting alternative or more complex explanations for TO presence in smallmouth bass from this region. This article is protected by copyright. All rights reserved
... The emerging contaminants include a range of synthetic and natural chemical compounds, such as drugs, hormones, endocrine disrupting chemicals, personal care products, pharmaceuticals, pesticides, surfactants, and flame retardants, whose occurrence and removal are often reported in the literature, although there is still a lack of knowledge concerning the various contaminants' fate [6][7][8][9][10][11][12]. Commonly, they are found in varied water matrices (e.g., wastewater, surface water, groundwater) in concentrations ranging from ng·L −1 to µg·L −1 [1,6,13]. However, to assess the new technologies' efficiency in removing emerging pollutants, higher concentrations in the order of mg·L −1 are used [14,15]. ...
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Domestic wastewater has been targeted for the presence of emerging contaminants such as antibiotics, of which diclofenac is one of the most frequently detected. Many studies have focused on the removal of these emerging pollutants. However, the legislation has focused on toxicity monitoring. In search of simplified solutions for rural areas, and to guarantee the safe reuse of effluent in agriculture, this study evaluated the efficiency of a decentralized solar disinfection (SODIS) system regarding the reduction of ecotoxicity, phytotoxicity, and pathogens in domestic wastewater after adding diclofenac potassium. For this purpose, the bioindicators Artemia sp., Allium cepa L. and Lactuca sativa were used, after 1, 2, and 3 h of exposure to solar radiation. After 3 h of exposure to solar radiation, toxicity was reduced and root growth inhibition was noted, which indicates low effluent toxicity after treatment by the SODIS system. It was achieved a reduction of 3 and 2 log units in the concentration of total coliforms and Escherichia coli, respectively.
... Ongoing research produces more and more evidence that pharmaceutical ingredients in the environment can have adverse effects. Studies in the Potomac River Basin in the United States have shown that chemical drugs are inextricably linked to fish mortality and a high prevalence of intersex or testicular oocytes [9]. The psychotropic oxazepam and 17α-ethynylestradiol can, respectively, affect the sexual characteristics and habitat behavior of male fish [10,11]. ...
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The total amount of drug waste is expanding significantly as populations age and societies become wealthier. Drug waste is becoming a problem for health and the environment. Thus, how to reduce and effectively dispose of drug waste is increasingly becoming an issue for society. This study focuses on household drug management, which involves five sub-practices: selection, purchasing, using, storing, and disposing of drugs. A questionnaire survey was conducted in a second-tier Chinese city that reveals both problems and opportunities in these five sub-practices. The results show that consumers are aware of significant issues with regard to the safe and effective use of drugs as well as with regard to proper ways of disposing of and recycling drugs. Moreover, our analysis reveals promising opportunities for addressing these issues by developing novel services based on the idea of connecting the five involved sub-practices of household drug management. Connecting and adjusting practices in this manner can be seen as an important factor in reducing drug waste and pharmaceutical pollutants.
Article
Aromatic compounds are widespread microbial growth substrates with natural as well as anthropogenic sources, albeit with their in situ concentrations and their bioavailabilities varying over several orders of magnitude. Even though degradation pathways and underlying regulatory systems have long been studied with aerobic and, to a lesser extent, with anaerobic bacteria, comparatively little is known about the effector concentration-dependent responsiveness. A. aromaticum EbN1 is a model organism for the anaerobic degradation of aromatic compounds with the architecture of the catabolic network and its substrate-specific regulation having been intensively studied by means of differential proteogenomics. The present study aims at unraveling the minimal concentration of an aromatic growth substrate ( p -hydroxyacetophenone here) required to initiate gene expression for its degradation pathway and to learn in principle about the lower limit of catabolic responsiveness of an anaerobic degradation specialist.
Article
Reuse of municipal and industrial wastewater treatment plant (WWTP) effluent is used to augment freshwater supplies globally. The Shenandoah River Watershed (U.S.A.) was selected to conduct on-site exposure experiments to assess endocrine disrupting characteristics of different source waters. This investigation integrates WWTP wastewater reuse modeling, hydrological and chemical characterization, and in vivo endocrine disruption bioassessment to assess contaminant sources, exposure pathways, and biological effects. The percentage of accumulated WWTP effluent in each river reach (ACCWW%) was used to predict environmental concentrations for consumer product chemicals (boron), pharmaceutical compounds (carbamazepine), and steroidal estrogens (estrone, 17-β-estradiol, estriol, and 17-α-ethinylestradiol). Fish endocrine disruption was evaluated using vitellogenin induction in adult male or larval fathead minnows. Water samples were analyzed for >500 inorganic and organic constituents to characterize the complex contaminant mixtures. Municipal ACCWW% at drinking water treatment plant surface water intakes ranged from <0.01 to 2.0% under mean-annual streamflow and up to 4.5% under mean-August streamflow. Measured and predicted environmental concentrations resulted in 17-β-estradiol equivalency quotients ranging from 0.002 to 5.0 ng L ⁻¹ indicating low-to-moderate risk of fish endocrine disruption. Results from the fish exposure experiments showed low (0.5- to 3.2-fold) vitellogenin induction in adult males.
Article
Intersex in wild fish populations has received considerable attention in the scientific literature and public media. Conventional detection of testicular oocytes (TO), the presence of immature oocytes within testis of male fish, employs transverse sectioning of excised testis and is lethal. This present study used a non-lethal laparoscopic technique to collect biopsies of testis from black bass, entering the body cavity via the genital pore. Detection of TO was compared between biopsy and conventional methods using 79 smallmouth bass (SMB) Micropterus dolomieu from 8 sites and 68 largemouth bass (LMB) M. salmoides from 4 sites. Both methods performed similarly at sites where TO severity was moderate or high (6 of 8 SMB sites) while transverse sectioning resulted in superior TO detection at sites where severity was low (2 of 8 SMB sites and all 4 LMB sites). In SMB, TO prevalence by transverse and biopsy methods was strongly correlated across sites (r(2) = 0.81) and severity reported by enumeration of TO was moderately correlated across sites (r(2 ) = 0.59). Survival of a subset of LMB (n = 20) to 28-d after laparoscopic surgery was 90%. This research indicates that laparoscopy may be useful for monitoring the prevalence and severity of TO in Micropterus species, particularly when lethal sampling is precluded. This article is protected by copyright. All rights reserved.
Article
The present study assesses the spatial distribution and temporal trends of the water dissolved phase (WDP), suspended particulate matter (SPM) and sediment partitioning of atrazine (ATR) and its metabolites in the Volturno River estuary. The load contribution of ATR and its metabolites in this river to the Central Mediterranean Sea was estimated. Samples were collected in 10 sampling sites during the four seasons. The total concentrations of ATR and DPs detected ranged from 18.1 to 105.5 ng L⁻¹ in WDP, from 4.5 to 63.2 ng L⁻¹ in SPM, and from 4.6 to 18.6 ng g⁻¹ in sediment samples, indicating high levels of these pollutants. Structural equation model and the ratio study indicated that the relationship between sediment and WDP pollutants occurred through the SPM. The pollutants load at the Volturno River in its mouth was evaluated in about 30.4 kg year⁻¹, showing that this river is an important source of these analytes through discharge into Central Mediterranean Sea. Principal component analysis indicated that ATR and its metabolites pollution moves from Volturno River mouth southward and increased in the rainy season. The desethylatrazine-to-atrazine ratio was higher than 0.5 for all samples analyzed, indicating an historical discharge and a long residence time of ATR in sediment about two decades after its ban, and classifying ATR as a nonpoint source contaminant. This study makes up the first record of ATR and its metabolites in superficial water of Southern Italy and provides helpful data as starting point for future studies.
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Water‐borne contaminants were monitored in 69 tributaries of the Laurentian Great Lakes in 2010 and 2014 using semipermeable membrane devices (SPMDs), and polar organic chemical integrative samplers (POCIS). A risk‐based screening approach was used to prioritize chemicals and chemical mixtures, identify sites at greatest risk for biological impacts, and identify potential hazards to monitor at those sites. Analyses included 185 chemicals (143 detected) including polycyclic aromatic hydrocarbons (PAHs), legacy and current‐use pesticides, fire retardants, pharmaceuticals, fragrances, and others. Hazard quotients were calculated by dividing detected concentrations by biological effect concentrations reported in the ECOTOX Knowledgebase (Toxicity quotients, TQs) or ToxCast database (Exposure Activity Ratios, EARs). Mixture effects were estimated by summation of EAR values for chemicals that influence ToxCast assays with common gene targets. Nineteen chemicals, including atrazine, DEET, di(2‐ethylhexyl)phthalate, dl‐menthol, galaxolide, p‐tert‐octylphenol, three organochlorine pesticides, three PAHs, four pharmaceuticals, and three phosphate flame retardants, had TQs greater than 0.1 or EARs for individual chemicals (EARchem) greater than 10‐3 at 10% or more of the sites monitored. An additional four chemicals (tributyl phosphate, triethyl citrate, benz(a)anthracene, and benzo(b)fluoranthene) were present in mixtures with EAR (EARmixture) greater than 10‐3. To evaluate potential apical effects and biological endpoints to monitor in exposed wildlife, in vitro bioactivity data were compared to adverse outcome pathway (AOP) and gene ontology information. Endpoints and effects associated with endocrine disruption, alterations in xenobiotic metabolism, and potentially neuronal development would be relevant to monitor at the priority sites. The EAR threshold exceedance for many chemical classes was correlated with urban land cover and wastewater effluent influence, while herbicides and fire retardants were also correlated to agricultural land cover. This article is protected by copyright. All rights reserved.
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This study determined the concentrations, origin, and associated ecological and human health risks of Ʃ28PCBs in soil profiles from selected telecom-masts in the Niger Delta, Nigeria. A total of 18 soil samples were quantified for Ʃ28PCBs with gas chromatography-mass spectrometry after soxhlet extraction with n-hexane/dichloromethane and purified with florisil and silica gel column. The occurrence of the ∑28PCBs varied widely, and ranged from 88.0 to 293 mg kg⁻¹, with pollution load in the order of subsoil > topsoil, and SS 3 > SS 2 > SS 1 > SS 6 > SS 7 > SS 9 > SS 4 > SS 8 > SS 5. The compositional pattern of the ∑28PCBs were in the order of deca-PCB > tetra-PCBs > di-PCBs > penta-PCBs > hexa-PCBs > hepta-PCBs > tri-PCBs > octa-PCBs > nona-PCBs. Also, the LC-PCBs are the dominant PCBs with a composition of 50 to 91.8%, while the HC-PCBs accounted for 34.8 to 78.8%. The levels of the ∑28PCBs from the telecom-masts were significantly higher than the recommended standards for urban and agricultural soils. The ecological risk index, toxic equivalence, hazard index, and total cancer risk suggest ecological risk to soil-dwelling organisms and on-site human occupational risk to soils around the telecom-masts. The source identification depicts that PCBs originated from the use of Aroclor1254 mixtures, cable and wire insulators, lubricants, paints, transformer oils, pesticides, and power capacitors in the telecom masts. Standard guidelines for the operations of telecom-masts should be carried out to mitigate the potential ecological and on-site human occupational risks in soil profiles around the telecom-masts, and similar land use somewhere else around the world.
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During recent decades, survey studies have documented the widespread presence of oocytes in the testes of male Smallmouth Bass Micropterus dolomieu collected from surface waters throughout the United States. There are few published reports of testicular oocytes (TO) in Smallmouth Bass before the 1990s, so it is difficult to know how long this has been occurring. Consequently, this study was conducted to evaluate the prevalence and severity of TO occurrence in whole fish specimens from two archival collections-the Smithsonian Institution's National Museum of Natural History in Suitland, Maryland, and Cornell University's Museum of Vertebrates in Ithaca, New York. Gonads were excised from 167 preserved male Smallmouth Bass that were originally collected between 1875 and 2004, and routine histologic sections were prepared and examined. The severity of TO was determined using a semiquantitative scoring system. Overall, 52.1% of male Smallmouth Bass were found to have TO. Affected fish had been collected in 11 of the 18 represented states, and TO were found in specimens harvested during decades as early as the 1880s and 1900s. Unfortunately, the small number of samples acquired at the earliest time periods precluded analyses of prevalence and severity trends over time. The results of this study demonstrated that the phenomenon of TO in male Smallmouth Bass is at least a century old and confirmed the widespread nature of this finding throughout the species' historic range. Further research efforts should focus on determining the baseline prevalence of TO in laboratory-reared male Smallmouth Bass that have not been exposed to endocrine active substances or the effects of experimental estrogen exposure on such fish.
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Excessively used pesticides in agricultural areas are spilled into aquatic environments, wherein they are suspended or sedimented. Owing to climate change, herbicides are the fastest growing sector of the pesticide industry and are detected in surface water, groundwater, and sediments near agricultural areas. In freshwater, organisms, including mussels, snails, frogs, and fish, are exposed to various types and concentrations of herbicides. Invertebrates are sensitive to herbicide exposure because their defense systems are incomplete. At the top of the food chain in freshwater ecosystems, fish show high bioaccumulation of herbicides. Herbicide exposure causes reproductive toxicity and population declines in freshwater organisms and further contamination of fish used for consumption poses a risk to human health. In addition, it is important to understand how environmental factors are physiologically processed and assess their impacts on reproductive parameters, such as gonadosomatic index and steroid hormone levels. Zebrafish is a good model for examining the effects of herbicides such as atrazine and glyphosate on embryonic development in freshwater fish. This review describes the occurrence and role of herbicides in freshwater environments and their potential implications for the reproduction and embryonic development of freshwater organisms.
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Urbanization contributes to the formation of novel elemental combinations and signatures in terrestrial and aquatic watersheds, also known as ‘chemical cocktails.’ The composition of chemical cocktails evolves across space and time due to: (1) elevated concentrations from anthropogenic sources, (2) accelerated weathering and corrosion of the built environment, (3) increased drainage density and intensification of urban water conveyance systems, and (4) enhanced rates of geochemical transformations due to changes in temperature, ionic strength, pH, and redox potentials. Characterizing chemical cocktails and underlying geochemical processes is necessary for: (1) tracking pollution sources using complex chemical mixtures instead of individual elements or compounds; (2) developing new strategies for co-managing groups of contaminants; (3) identifying proxies for predicting transport of chemical mixtures using continuous sensor data; and (4) determining whether interactive effects of chemical cocktails produce ecosystem-scale impacts greater than the sum of individual chemical stressors. First, we discuss some unique urban geochemical processes which form chemical cocktails, such as urban soil formation, human-accelerated weathering, urban acidification-alkalinization, and freshwater salinization syndrome. Second, we review and synthesize global patterns in concentrations of major ions, carbon and nutrients, and trace elements in urban streams across different world regions and make comparisons with reference conditions. In addition to our global analysis, we highlight examples from some watersheds in the Baltimore-Washington DC region, which show increased transport of major ions, trace metals, and nutrients across streams draining a well-defined land-use gradient. Urbanization increased the concentrations of multiple major and trace elements in streams draining human-dominated watersheds compared to reference conditions. Chemical cocktails of major and trace elements were formed over diurnal cycles coinciding with changes in streamflow, dissolved oxygen, pH, and other variables measured by high-frequency sensors. Some chemical cocktails of major and trace elements were also significantly related to specific conductance (p < 0.05), which can be measured by sensors. Concentrations of major and trace elements increased, peaked, or decreased longitudinally along streams as watershed urbanization increased, which is consistent with distinct shifts in chemical mixtures upstream and downstream of other major cities in the world. Our global analysis of urban streams shows that concentrations of multiple elements along the Periodic Table significantly increase when compared with reference conditions. Furthermore, similar biogeochemical patterns and processes can be grouped among distinct mixtures of elements of major ions, dissolved organic matter, nutrients, and trace elements as chemical cocktails. Chemical cocktails form in urban waters over diurnal cycles, decades, and throughout drainage basins. We conclude our global review and synthesis by proposing strategies for monitoring and managing chemical cocktails using source control, ecosystem restoration, and green infrastructure. We discuss future research directions applying the watershed chemical cocktail approach to diagnose and manage environmental problems. Ultimately, a chemical cocktail approach targeting sources, transport, and transformations of different and distinct elemental combinations is necessary to more holistically monitor and manage the emerging impacts of chemical mixtures in the world's fresh waters.
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Smallmouth bass Micropterus dolomieu were sampled from three sites within the Lake Erie drainage (Elk Creek, Twentymile Creek, and Misery Bay, an embayment in Presque Isle Bay). Plasma, tissues for histopathological analyses, and liver and testes preserved in RNALater® were sampled from 30 smallmouth bass (of both sexes) at each site. Liver and testes samples were analyzed for transcript abundance with Nanostring nCounter® technology. Evidence of estrogenic endocrine disruption was assessed by the presence and severity of intersex (testicular oocytes; TO) and concentrations of plasma vitellogenin in male fish. Abundance of 17 liver transcripts associated with reproductive function, endocrine activity, and contaminant detoxification pathways and 40 testes transcripts associated with male and female reproductive function, germ cell development, and steroid biosynthesis were also measured. Males with a high rate of TO (87–100%) and plasma vitellogenin were noted at all sites; however, TO severity was greatest at the site with the highest agricultural land cover. Numerous transcripts were differentially regulated among the sites and patterns of transcript abundance were used to better understand potential risk factors for estrogenic endocrine disruption. The results of this study suggest endocrine disruption is prevalent in this region and further research would benefit to identify the types of contaminants that may be associated with the observed biological effects.
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Signs of disease, such as external lesions, have been prevalent in smallmouth bass throughout the Susquehanna River Basin, USA. Previous targeted chemical studies in this system have identified known persistent organic pollutants, but a common explanatory link across multiple affected sites remains undetermined. A fast and robust extraction method that can be applied to young-of-year fish is needed to effectively screen for target and non-target compounds that may be impacting organism health. The quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction methodology was optimized to perform both targeted and non-targeted chemical analyses from a single extraction of whole young-of-year fish. Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS) was used for extract analysis. Sample extraction was performed using the solvent ethyl acetate, followed by a two-step cleanup in which samples were frozen for lipid removal and subjected to dispersive solid phase extraction using Florisil. A sample of 21 young-of-year smallmouth bass collected from areas with disease and exhibiting different types of external lesions were evaluated for 233 target compounds. A total of 34 organic contaminants, including polychlorinated biphenyls, brominated diphenyl ethers, organochlorinated pesticides, and personal care products, were detected. Data from this sample set was then analyzed for non-targets. Using the Fisher ratio method and multivariate analysis, an additional 10 significant features were identified specific to either fish with visible lesions or with no visible disease characteristics.
Chapter
The end of World War II brought DDT and other organic pesticides to Chesapeake Bay agriculture. These new insecticides and herbicides supported the industrialization of farming that primarily produced feedstock for the manufacture of animal-based foods. The widespread use of these new chemicals constituted a war on nature with the intent of poisoning non-human animals that ate crops and weeds that competed for land, space, light, nutrients, and water. The pesticides tended to fail as the artificial selection they imposed on their targets promoted the evolution of resistant pests. In the 1960s, herbicides replaced insecticides as the dominant pesticide. Genetic engineered pesticide resistant corn and soybean facilitated the marketing of the generalist herbicides glyphosate, and later dicamba. The genetically engineered crops and pesticide dominate the animal feedstock agriculture in the region. Years of pesticide use have contaminated water, soils, fish and wildlife. The pesticides threaten both human health and that of the environment. Adopting sustainable organic agricultural practices can end the war on nature and help recover the health of the Chesapeake Bay ecosystem and that of its people.
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Smallmouth bass Micropterus dolomieu is an economically important sportfish and within the Chesapeake Bay watershed has experienced a high prevalence of external lesions, infectious disease, mortality events, reproductive endocrine disruption and population declines. To date, no clear or consistent associations with contaminants measured in fish tissue or surface water have been found. Therefore, plasma samples from two sites in the Potomac River and two in the Susquehanna River drainage basins, differing in land-use characteristics, were utilized to determine if perfluoroalkyl substances were present. Four compounds, perfluorooctane sulphonic acid (PFOS), perfluoroundecanoic acid (PFUnA), perfluorodecanoic acid (PFDA) and perfluorododecanoic acid (PFDoA), were detected in every fish. Two additional compounds, perfluorooctane sulphonamide (PFOSA) and perfluorononanoic acid (PFNA), were less commonly detected at lower concentrations, depending on the site. Concentrations of PFOS (up to 574 ng/mL) were the highest detected and varied significantly among sites. No seasonal differences (spring versus fall) in plasma concentrations were observed. Concentrations of PFOS were not significantly different between the sexes. However, PFUnA and PFDoA concentrations were higher in males than females. Both agricultural and developed land-use appeared to be associated with exposure. Further research is needed to determine if these compounds could be affecting the health of smallmouth bass and identify sources.
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Endocrine disrupting contaminants are of continuing concern for potentially contributing to reproductive dysfunction in largemouth and smallmouth bass in the Chesapeake Bay watershed (CBW) and elsewhere. Exposures to atrazine (ATR) have been hypothesized to have estrogenic effects on vertebrate endocrine systems. The incidence of intersex in male smallmouth bass from some regions of CBW has been correlated with ATR concentrations in water. Fish early life stages may be particularly vulnerable to ATR exposure in agricultural areas, as a spring influx of pesticides coincides with spawning and early development. Our objectives were to investigate the effects of early life stage exposure to ATR or the model estrogen 17α-ethinylestradiol (EE2) on sexual differentiation and gene expression in gonad tissue. We exposed newly hatched largemouth bass (LMB, Micropterus salmoides ) from 7 to 80 days post-spawn to nominal concentrations of 1, 10, or 100 µg ATR/L or 1 or 10 ng EE2/L and monitored histological development and transcriptomic changes in gonad tissue. We observed a nearly 100% female sex ratio in LMB exposed to EE2 at 10 ng/L, presumably due to sex reversal of males. Many gonad genes were differentially expressed between sexes. Multidimensional scaling revealed clustering by gene expression of the 1 ng EE2/L and 100 µg ATR/L-treated male fish. Some pathways responsive to EE2 exposure were not sex-specific. We observed differential expression in male gonad in LMB exposed to EE2 at 1 ng/L of several genes involved in reproductive development and function, including star , cyp11a2 , ddx4 (previously vasa ), wnt5b , cyp1a and samhd1 . Expression of star , cyp11a2 and cyp1a in males was also responsive to ATR exposure. Overall, our results confirm that early development is a sensitive window for estrogenic endocrine disruption in LMB and are consistent with the hypothesis that ATR exposure induces some estrogenic responses in the developing gonad. However, ATR-specific and EE2-specific responses were also observed.
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Alzheimer’s disease (AD) is one of the most common neurodegenerative diseases. The association between environmental factors (e.g., pesticide) and AD has attracted considerable attention. However, no systematic analysis has been performed and make it difficult to provide deeper insights of AD correlated with pesticide exposure. Hence, this study utilized a bibliometric and visual approach that included map collaborations, co-citations, and keywords, to identifying the knowledge structure, hot topics and the research trends based on 372 publications from the Web of Science Core Collection and PubMed databases. The results showed that 116 institutions from 52 countries published articles in this field. The United States and Israel played a leading role with numerous publications in related journals, as well as prolific institutions and authors, respectively. Three hot topics in pesticide-induced AD were recognized based on co-occurrence keywords detection, including acetylcholinesterase (AChE) inhibitor, oxidative stress, and AChE. Moreover, analysis of keywords burst suggests that some potential molecular mechanisms and therapy targets of pesticide-induced AD, especially for mitochondrial dysfunction and monoamine oxidase-B (MAO-B) that catalyzes the oxidative deamination and causes oxidative stress, are emerging trends. In addition, the study of various pesticides and the assessment method of pesticide exposure will step forward as well. To the best of our knowledge, this study is the first to specifically visualize the relationship between AD and pesticide exposure and to predict potential future research directions.
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The vast number of chemicals potentially reaching aquatic environment pose a challenge in maintaining the quality of water resources. However, best management practices to improve water quality are typically focused on reducing nutrient transport without assessing how these practices may impact the occurrence of micropollutants. The potential for co-management of nutrients and organic micropollutants exists, but few studies have comprehensively evaluated the suite of contaminants associated with different water quality management practices (riparian zone restoration, stormwater management, etc.). Furthermore, most studies dealing with the determination of micropollutants in environmental samples include only a limited number of target analytes, leaving many contaminants undetected. To address this limitation, there has been a gradual shift in environmental monitoring from using target analysis to either suspect screening analysis (SSA) or non-targeted analysis (NTA), which relies on accurate mass measurements, mass spectral fragmentation patterns, and retention time information obtained using liquid chromatography coupled to high-resolution mass spectrometry. The work presented in this paper focuses on a wide-scope detection of micropollutants in surface water samples from the Potomac River watershed (United States). An in-house database composed of 1039 compounds based on experimental analysis of primary standards was established, and SSA workflow was optimized and applied to determine the presence of micropollutants in surface water. A total of 103 micropollutants were detected in the samples, some of which are contaminants that were not previously monitored and belong to various classes such as pharmaceuticals, personal care products, per-and polyfluoroalkyl substances and other persistent industrial chemicals. The impact of best management practices being implemented for nitrogen and phosphorus reductions were also assessed for their potential to reduce micropollutant transport. This work illustrates the advantages of suspect screening methods to determine a large number of micropollutants in environmental samples and reveals the potential to co-manage a diverse array of micropollutants based on shared transport and transformation mechanisms in watersheds.
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If not managed properly, modern agricultural practices can alter surface and groundwater quality and drinking water resources resulting in potential negative effects on aquatic and terrestrial ecosystems. Exposure to agriculturally derived contaminant mixtures has the potential to alter habitat quality and negatively affect fish and other aquatic organisms. Implementation of conservation practices focused on improving water quality continues to increase particularly in agricultural landscapes throughout the United States. The goal of this study was to determine the consequences of land management actions on the primary drivers of contaminant mixtures in five agricultural watersheds in the Chesapeake Bay, the largest watershed of the Atlantic Seaboard in North America where fish health issues have been documented for two decades. Surface water was collected and analyzed for 301 organic contaminants to determine the benefits of implemented best management practices (BMPs) designed to reduce nutrients and sediment to streams in also reducing contaminants in surface waters. Of the contaminants measured, herbicides (atrazine, metolachlor), phytoestrogens (formononetin, genistein, equol), cholesterol and total estrogenicity (indicator of estrogenic response) were detected frequently enough to statistically compare to seasonal flow effects, landscape variables and BMP intensity. Contaminant concentrations were often positively correlated with seasonal stream flow, although the magnitude of this effect varied by contaminant across seasons and sites. Land-use and other less utilized landscape variables including biosolids, manure and pesticide application and percent phytoestrogen producing crops were inversely related with site-average contaminant concentrations. Increased BMP intensity was negatively related to contaminant concentrations indicating potential co-benefits of BMPs for contaminant reduction in the studied watersheds. The information gained from this study will help prioritize ecologically relevant contaminant mixtures for monitoring and contributes to understanding the benefits of BMPs on improving surface water quality to better manage living resources in agricultural landscapes inside and outside the Chesapeake Bay watershed.
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This study evaluated the occurrence characteristics to trace the origin and associated risks of organochlorine pesticides (OCPs) in soils from urban, suburban, and rural stormwater reservoirs. Samples were collected from the topsoil (0–15 cm) and subsoil (15-30 cm), and quantified for Ʃ20OCPs using a gas chromatography-mass spectrometry (GC-MS) after extraction with n-hexane and dichloromethane. The concentrations of ∑20OCPs ranged from 29.3 to 77.9 ng g⁻¹. The average concentration of Σ20OCPs in the catchments and the isomer compositional pattern is in the order of urban > sub-urban > rural and ∑HCHs > ∑Chlordane > ∑Drins > ∑Endosulfan > ∑DDTs respectively. The HI levels for infants’ exposure were seven-fold that of adults' exposure and were > 1. The human exposure risk is in the order of RiskIng > RiskDerm > RiskInh. The RiskIng and RiskDerm in infants’ exposure were higher than in adults’ exposure, while the RiskInh in adult exposure was higher than that of infants' exposure. The total cancer risk was higher than the acceptable total cancer risk value. The ecological risk indicated a significant biological effect in 56% of the samples. The source apportionment showed that Ʃ20OCPs were of historical and fresh inputs from the non-point and direct origin. Standard clean-up and source-directed mitigation actions should be carried out to assuage the associated risks.
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Exposure to multiple classes of contaminants, both legacy and those of emerging concern (CECs), were assessed in tree swallow (Tachycineta bicolor) tissue and diet samples from six sites along the Maumee River, Ohio to understand both exposure and possible effects of exposure to those CECs for which there are little avian data. The six sites represented a gradient from intensive agriculture upstream to highly urbanized and industrial landscapes downstream; 1 – 2 remote Wisconsin lakes were assessed for comparative purposes. Cytochrome P450 induction, DNA damage, and thyroid function were also assessed relative to contaminant exposure. Bioaccumulative CECs, such as polybrominated diphenyl ethers (PBDEs) and perfluorinated substances, did not follow any upstream to downstream gradient, but both had significantly greater concentrations along the Maumee River than at the remote lake sites. Greater exposure to PBDEs was apparent in swallows at or near wastewater treatment facilities than at other sites. Total polychlorinated biphenyl and total polycyclic aromatic hydrocarbon concentrations were at greater concentrations in swallows at downstream locations compared to upstream sites and were associated with higher ethoxyresorufin‐O‐dealkylase activity. Few herbicides or non‐organochlorine insecticides were detected in swallow tissues or their food, except for atrazine and its metabolite desethylatrazine. Few pharmaceuticals and personal care products were detected except for DEET and iopamidol. Both were detected in most liver samples, but not in eggs, and were detected at the remote lake sites as well. This is one of the most comprehensive assessments to date of exposure and effects of a wide variety of CECs in birds. This article is protected by copyright. All rights reserved.
Technical Report
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Method report available at https://nwql.usgs.gov/Public/rpt.shtml?WRIR-01-4098 A method for the isolation and analysis of 21 parent pesticides and 20 pesticide degradates in natural-water samples is described. Water samples are filtered to remove suspended particulate matter and then are pumped through disposable solid-phase-extraction columns that contain octadecyl-bonded porous silica to extract the analytes. The columns are dried by using nitrogen gas, and adsorbed analytes are eluted with ethyl acetate. Extracted analytes are determined by capillary-column gas chromatography/mass spectrometry with selected-ion monitoring of three characteristic ions. The upper concentration limit is 2 micrograms per liter (µg/L) for most analytes. Single-operator method detection limits in reagent-water samples range from 0.00 1 to 0.057 µg/L. Validation data also are presented for 14 parent pesticides and 20 degradates that were determined to have greater bias or variability, or shorter holding times than the other compounds. The estimated maximum holding time for analytes in pesticide-grade water before extraction was 4 days. The estimated maximum holding time for analytes after extraction on the dry solid-phase-extraction columns was 7 days. An optional on-site extraction procedure allows for samples to be collected and processed at remote sites where it is difficult to ship samples to the laboratory within the recommended pre-extraction holding time. The method complements existing U.S. Geological Survey Method O-1126-95 (NWQL Schedules 2001 and 2010) by using identical sample preparation and comparable instrument analytical conditions so that sample extracts can be analyzed by either method to expand the range of analytes determined from one water sample.
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This report presents the study design, environmental data, and quality-assurance data for an integrated chemical and biological study of selected streams or lakes that receive wastewater-treatment plant effluent in Minnesota. This study was a cooperative effort of the U.S. Geological Survey, the Minnesota Pollution Control Agency, St. Cloud State University, the University of St. Thomas, and the University of Colorado. The objective of the study was to identify distribution patterns of endocrine active chemicals, pharmaceuticals, and other organic and inorganic chemicals of concern indicative of wastewater effluent, and to identify biological characteristics of estrogenicity and fish responses in the same streams. The U.S. Geological Survey collected and analyzed water, bed-sediment, and quality-assurance samples, and measured or recorded streamflow once at each sampling location from September through November 2009. Sampling locations included surface water and wastewater-treatment plant effluent. Twenty-five wastewater-treatment plants were selected to include continuous flow and periodic release facilities with differing processing steps (activated sludge or trickling filters) and plant design flows ranging from 0.002 to 10.9 cubic meters per second (0.04 to 251 million gallons per day) throughout Minnesota in varying land-use settings. Water samples were collected from the treated effluent of the 25 wastewater-treatment plants and at one point upstream from and one point downstream from wastewater-treatment plant effluent discharges. Bed-sediment samples also were collected at each of the stream or lake locations. Water samples were analyzed for major ions, nutrients, trace elements, pharmaceuticals, phytoestrogens and pharmaceuticals, alkylphenols and other neutral organic chemicals, carboxylic acids, and steroidal hormones. A subset (25 samples) of the bed-sediment samples were analyzed for carbon, wastewater-indicator chemicals, and steroidal hormones; the remaining samples were archived. Biological characteristics were determined by using an in-vitro bioassay to determine total estrogenicity in water samples and a caged fish study to determine characteristics of fish from experiments that exposed fish to wastewater effluent in 2009. St. Cloud State University deployed and processed caged fathead minnows at 13 stream sites during September 2009 for the caged fish study. Measured fish data included length, weight, body condition factor, and vitellogenin concentrations.
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The physiological basis for well-known correlations between summer air temperature indices and year-class strength in northern smallmouth bass (Micropterus dolomieui) populations was examined. Field and laboratory studies demonstrated the existence of two critical stages in early life when smallmouth bass are particularly vulnerable to features characteristic of many natural water temperature regimes. The first stage extends from fertilization until the young leave the nest; high mortality results from exposure to extreme temperatures. The second stage extends over the first winter, when the young subsist on accumulated energy reserves. Because the ratio of energy stored to basal metabolic rate increases with size, large fish can with stand winter starvation better than small fish. The results from these and other studies were incorporated into a deterministic model of the relations between temperature and first-year survival of smallmouth bass. Analysis of water temperature time series data from many locations led to the development and parameterization of a stochastic model capable of simulating variations in water temperature characteristic of the littoral zones of typical North American lakes. The stochastic physical and deterministic biological models were used together to assess the effects on first-year survival of changes in climate and of realistic changes in the magnitudeand frequency of short-term temperature fluctuations. The model successfully predicted the observed northern limit of the species' range. It also generated approximate environmental criteria for judging when year-to-year variation in survival, over one or both of the critical life history stages identified, is likely to reach a level sufficiently great to determine the pattern of year-to-year variation in recruitment to the adult stock. The combined model was also used to assess the effects of thermal loading from a nuclear power plant on a particular population.
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Significant amounts of antibiotics enter the environment via point and nonpoint sources. We examined the temporal dynamics of tetracycline exposure to stream periphyton and associated organisms across a logarithmically dosed-series of experimental mesocosms, designed to mimic natural conditions. Target in-stream tetracycline exposures were based on environmentally relevant concentrations in aquatic ecosystems throughout the United States (<1-100 μg L(-1)). Significant changes in the stream biotic community were observed within 7 days with in-stream tetracycline concentrations as low as 0.5 μg L(-1), including significant changes in antibiotic resistance, bacteria abundance and productivity, algae biomass, cyanobacteria, organic biomass, and nematodes. These effects were magnified with increased exposure time and dosing concentration. Recovery of the periphyton community after 28 days of exposure was dependent upon the tetracycline dose. At the highest doses, 10 and 100 μg L(-1), bacteria productivity recovered; however, bacteria, algae, and nematode abundance did not recover at the same rate and remained low even after a 28-day recovery period (of nondosing). This study demonstrates that tetracycline exposure under near-natural conditions and at concentrations currently observed in aquatic environments may have important consequences for the structure and function of stream periphyton and, potentially, public health via increasing resistance of naturally occurring bacteria.
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A high prevalence of intersex or testicular oocytes (TO) in male smallmouth bass within the Potomac River drainage has raised concerns as to the health of the river. Studies were conducted to document biomarker responses both temporally and spatially to better understand the influence of normal physiological cycles, as well as water quality and land-use influences. Smallmouth bass were collected over a 2-year period from three tributaries of the Potomac River: the Shenandoah River, the South Branch Potomac and Conococheague Creek, and an out-of-basin reference site on the Gauley River. The prevalence of TO varied seasonally with the lowest prevalence observed in July, post-spawn. Reproductive maturity and/or lack of spawning the previous spring, as well as land-use practices such as application of manure and pesticides, may influence the seasonal observations. Annual, seasonal, and site differences were also observed in the percentage of males with measurable concentrations of plasma vitellogenin, mean concentration of plasma vitellogenin in females, and plasma concentrations of 17β-estradiol and testosterone in both sexes. Bass collected in the South Branch Potomac (moderate to high prevalence of TO) had less sperm per testes mass with a lower percentage of those sperm being motile when compared to those from the Gauley River (low prevalence of TO). An inverse relationship was noted between TO severity and sperm motility. An association between TO severity and wastewater treatment plant flow, percent of agriculture, total number of animal feeding operations, the number of poultry houses, and animal density within the catchment was observed.
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During the last decade, a number of studies have shown that, in addition to their classically described reproductive function, estrogens and androgens also regulate the immune system in teleosts. Today, several molecules are known to interfere with the sex-steroid signaling. These chemicals are often referred to as endocrine disrupting contaminants (EDCs). We review the growing evidence that these compounds interfere with the fish immune system. These studies encompass a broad range of approaches from field studies to those at the molecular level. This integrative overview improves our understanding of the various endocrine-disrupting processes triggered by these chemicals. Furthermore, the research also explains why fish that have been exposed to EDCs are more sensitive to pathogens during gametogenesis. In this review, we first discuss the primary actions of sex-steroid-like endocrine disruptors in fish and the specificity of the fish immune system in comparison to mammals. Then, we review the known interactions between the immune system and EDCs and interpret the primary effects of sex steroids (estrogens and androgens) and their related endocrine disruptors on immune modulation. The recent literature suggests that immune parameters may be used as biomarkers of contamination by EDCs. However, caution should be used in the assessment of such immunotoxicity. In particular, more attention should be paid to the specificity of these biomarkers, the external/internal factors influencing the response, and the transduction pathways induced by these molecules in fish. The use of the well-known mammalian models provides a useful guide for future research in fish.
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Skin lesions and spring mortality events of smallmouth bass Micropterus dolomieu and selected other species were first noted in the South Branch of the Potomac River in 2002. Since that year morbidity and mortality have also been observed in the Shenandoah and Monocacy rivers. Despite much research, no single pathogen, parasite, or chemical cause for the lesions and mortality has been identified. Numerous parasites, most commonly trematode metacercariae and myxozoans; the bacterial pathogens Aeromonas hydrophila, Aeromonas salmonicida, and Flavobacterium columnare; and largemouth bass virus have all been observed. None have been consistently isolated or observed at all sites, however, nor has any consistent microscopic pathology of the lesions been observed. A variety of histological changes associated with exposure to environmental contaminants or stressors, including intersex (testicular oocytes), high numbers of macrophage aggregates, oxidative damage, gill lesions, and epidermal papillomas, were observed. The findings indicate that selected sensitive species may be stressed by multiple factors and constantly close to the threshold between a sustainable (healthy) and nonsustainable (unhealthy) condition. Fish health is often used as an indicator of aquatic ecosystem health, and these findings raise concerns about environmental degradation within the Potomac River drainage. Unfortunately, while much information has been gained from the studies conducted to date, due to the multiple state jurisdictions involved, competing interests, and other issues, there has been no coordinated approach to identifying and mitigating the stressors. This synthesis emphasizes the need for multiyear, interdisciplinary, integrative research to identify the underlying stressors and possible management actions to enhance ecosystem health.
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Estuarine shallow areas and coastal lagoons are known to receive and concentrate multiple inputs, either from land, rivers or coastal areas, being intensively impacted by chemical contamination, namely endocrine disrupting chemicals (EDCs). Despite the ubiquitous coexistence of several classes of EDCs in most of these aquatic ecosystems, there is still limited information regarding their combined effects. Furthermore, given the immediate implications for population dynamics, the available laboratory studies almost invariably focus on very specific life history stages, such as embryonic development or reproduction, thus creating a gap on our knowledge of what happens in between. During this ‘intermediate phase’, the newborn larvae and juveniles face numerous challenges whose outcome may impair reproduction or even survival.
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The widespread occurrence of feminized male fish downstream of some wastewater treatment works has led to substantial interest from ecologists and public health professionals. This concern stems from the view that the effects observed have a parallel in humans, and that both phenomena are caused by exposure to mixtures of contaminants that interfere with reproductive development. The evidence for a "wildlife-human connection" is, however, weak: Testicular dysgenesis syndrome, seen in human males, is most easily reproduced in rodent models by exposure to mixtures of antiandrogenic chemicals. In contrast, the accepted explanation for feminization of wild male fish is that it results mainly from exposure to steroidal estrogens originating primarily from human excretion. We sought to further explore the hypothesis that endocrine disruption in fish is multicausal, resulting from exposure to mixtures of chemicals with both estrogenic and antiandrogenic properties. We used hierarchical generalized linear and generalized additive statistical modeling to explore the associations between modeled concentrations and activities of estrogenic and antiandrogenic chemicals in 30 U.K. rivers and feminized responses seen in wild fish living in these rivers. In addition to the estrogenic substances, antiandrogenic activity was prevalent in almost all treated sewage effluents tested. Further, the results of the modeling demonstrated that feminizing effects in wild fish could be best modeled as a function of their predicted exposure to both antiandrogens and estrogens or to antiandrogens alone. The results provide a strong argument for a multicausal etiology of widespread feminization of wild fish in U.K. rivers involving contributions from both steroidal estrogens and xenoestrogens and from other (as yet unknown) contaminants with antiandrogenic properties. These results may add further credence to the hypothesis that endocrine-disrupting effects seen in wild fish and in humans are caused by similar combinations of endocrine-disrupting chemical cocktails.
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Book
This is the original first edition published as a physical book by Elsevier. It is woefully out of date. An updated electronic version was published in 2002 by the U.S. Geological Survey, and a completely revised 2020 version with updated methods and supporting materials is listed in my publication list, and is available for download at https://doi.org/10.3133/tm4a3 .
Article
The occurrence of hermaphrodite fish in the lagoons of sewage treatment works led us to hypothesize that sewage effluent might contain a substance, or substances, estrogenic to fish. to test this hypothesis, we placed cages containing rainbow trout in the effluent from sewage-treatment works, and one to three weeks later measured the vitellogenin concentration in the plasma of the fish. Vitellogenin is a protein synthesized by the liver of oviparous fish in response to estradiol stimulation; it is then conveyed by the blood to the ovary, where it is sequestered by oocytes to form the yolk. Thus, the presence of vitellogenin in the plasma is indicative of estrogenic stimulation of the liver. an initial study, at a sewage-treatment works, showed that plasma vitellogenin concentrations rose rapidly and very markedly (over 1000-fold in three weeks) when trout were maintained in the effluent. an extensive nationwide survey was then conducted. Results were obtained from fifteen sewage-treatment works distributed throughout England. in all cases, exposure of trout to effluent resulted in a very pronounced increase (500 to 100,000-fold, depending on site) in the plasma vitellogenin concentration. Induction of vitellogenesis was also observed in carp, but to a much lesser extent than in trout.The identity of the estrogenic substance is unknown. It is suggested that the two most likely possibilities are ethynylestradiol, originating from pharmaceutical use, or alkylphenol-ethoxylates (APE), originating from the biodegradation of surfactants and detergents during sewage treatment.Laboratory studies on the potency of ethynylestradiol demonstrated that levels as low as 1 to 10 ng 1 could generate the response shown by the caged fish and that positive responses may arise at 0.1 to 0.5 ng 1. Further work is in progress on the potency of APE.
Book
Many important chemical transformations involve oxidative and reductive steps, also called redox reactions. The thermodynamics of these electron-transfer changes are discussed in terms of the Gibbs free energy changes and the corresponding reduction potentials, leading to the Nernst equation formulation. With this result, the spontaneity of redox reactions under environmental conditions (e.g., pH 7) is examined. Although many redox transformations are thermodynamically favored, they prove to be kinetically limited. The general sequence of steps leading to electron transfer is described, and the relative reactivities of structurally-related compounds are examined to assess what the likely rate-limiting processes involve. The importance of electron-transfer mediators in many environmental systems is illustrated.
Chapter
The disciplines of fish immunology and endocrinology have periodically met at a cross-road. This interdisciplinary overlap is perhaps most evident in the case of stress physiology. Such research has clearly demonstrated intersystem communication in which ligands traditionally associated with the endocrine system affect target cells of the immune system. However other ligands of the endocrine system, namely estrogens, are also known to exert actions on cells of the immune system. In the instance of fish immunology, documentation of such intersystem communication is scarce. Given the recognition of estrogenic endocrine disrupting chemicals in the environment and the increased application of immune status as an indicator of wild fish health, it is essential that mechanistic and physiological effects of estrogen on immune function are elucidated in fish. The following chapter is a general review of the effects of steroid hormones on immune function. The effects of estrogens on immune function in mammals and fish are specifically emphasized, and the possible significance of estrogenic endocrine disrupting chemicals is also considered.