Comparing biological effects and potencies of estrone and 17β-estradiol in mature fathead minnows, Pimephales promelas

Comparative effects of curcumin, nano curcumin and their combination on reproductive traits and spawning performance of red tilapia (Oreochromis Niloticus X O. Mossambicus)

Curcumin, the main polyphenol component of turmeric powder, has garnered increasing attention as an effective supplement in fish diets. A comparative trial was conducted to evaluate the impacts of dietary supplementation with different forms of curcumin (free, in combination, or nanoparticles) on hemato-biochemical parameters, reproductive capacity, and related gene expressions of red tilapia (Oreochromis niloticus x O. mossambicus) broodstock. Fish (n = 168) were fed an isonitrogenous (30% CP), isocaloric (18.72 MJ kg - 1) diet containing basal diet (Control), 60 mg kg-1 of either free curcumin (Cur), curcumin/nano-curcumin blend (Cur/NCur), or nano-curcumin (NCur) for 56 days. Red tilapia broodstock (155 ± 5.65 g) were stocked at a male: female ratio of 1:3. Blood samples and gonads were collected to assess hemato-biochemical parameters, reproductive capacity, and related gene expression at the end of the feeding trial. The results indicated that the values of hematological parameters (RBCs, WBCs, hemoglobin), total protein, albumin values, and reproductive hormones (T, LH, and FSH) were significantly increased, while liver function enzymes were decreased in the NCur group (P < 0.05). Reproductive performances (GSI, gonad maturation, total number of fry per female) were significantly improved in the NCur group compared with those in other groups (p < 0.05). The expression of reproductive genes (CYP19A1A, FSHR, LHR, FOXL2A, ESR1, ESR2A, and PGR) were significantly up-regulated in the gonads of fish fed NCur. Collectively, feeding red tilapia diets containing NCur led to noticeably better results followed by Cur/NCur blend, then free Cur compared to the control diet. These results indicate the superiority of NCur over its free or blended form, suggesting that a diet containing about 60 mg/kg of NCur is beneficial for enhancing hemato-biochemical parameters, improving reproductive performance, and enhancing the gonadal architecture of red tilapia.

Putative adverse outcome pathway development based on physiological responses of female fathead minnows to model estrogen versus androgen receptor agonists

Several adverse outcome pathways (AOPs) have linked molecular initiating events like aromatase inhibition, androgen receptor (AR) agonism, and estrogen receptor (ER) antagonism to reproductive impairment in adult fish. Estrogen receptor agonists can also cause adverse reproductive effects, however, the early key events (KEs) in an AOP leading to this are mostly unknown. The primary aim of this study was to develop hypotheses regarding the potential mechanisms through which exposure to ER agonists might lead to reproductive impairment in female fish. Mature fathead minnows were exposed to 1 or 10 ng 17α-ethynylestradiol (EE2)/L or 10 or 100 µg bisphenol A (BPA)/L for 14 d. The response to EE2 and BPA was contrasted with the effects of 500 ng/L of 17β-trenbolone (TRB), an AR agonist, as well as TRB combined with the low and high concentrations of EE2 or BPA tested individually. Exposure to 10 ng EE2/L, 100 µg BPA/L, TRB, or the various mixtures with TRB caused significant decreases in plasma concentrations of 17β-estradiol. Exposure to TRB alone caused a significant reduction in plasma vitellogenin (VTG), but VTG was unaffected or even increased in females exposed to EE2 or BPA alone or, in most cases, in mixtures with TRB. Over the course of the 14-d exposure, the only treatments that clearly did not affect egg production were 1 ng EE2/L and 10 µg BPA/L. Based on these results and knowledge of hypothalamic-pituitary-gonadal axis function, we hypothesize an AOP whereby decreased production of maturation-inducing steroid leading to impaired oocyte maturation and ovulation, possibly due to negative feedback or direct inhibitory effects of membrane ER activation, could be responsible for causing adverse reproductive impacts in female fish exposed to ER agonists.

Contaminant Exposure and Transport from Three Potential Reuse Waters within a Single Watershed

Global demand for safe and sustainable water supplies necessitates a better understanding of contaminant exposures in potential reuse waters. In this study, we compared exposures and load contributions to surface water from the discharge of three reuse waters (wastewater effluent, urban stormwater, and agricultural runoff). Results document substantial and varying organic-chemical contribution to surface water from effluent discharges (e.g., disinfection byproducts [DBP], prescription pharmaceuticals, industrial/household chemicals), urban stormwater (e.g., polycyclic aromatic hydrocarbons, pesticides, nonprescription pharmaceuticals), and agricultural runoff (e.g., pesticides). Excluding DBPs, episodic storm-event organic concentrations and loads from urban stormwater were comparable to and often exceeded those of daily wastewater-effluent discharges. We also assessed if wastewater-effluent irrigation to corn resulted in measurable effects on organic-chemical concentrations in rain-induced agricultural runoff and harvested feedstock. Overall, the target-organic load of 491 g from wastewater-effluent irrigation to the study corn field during the 2019 growing season did not produce substantial dissolved organic-contaminant contributions in subsequent rain-induced runoff events. Out of the 140 detected organics in source wastewater-effluent irrigation, only imidacloprid and estrone had concentrations that resulted in observable differences between rain-induced agricultural runoff from the effluent-irrigated and nonirrigated corn fields. Analyses of pharmaceuticals and per-/polyfluoroalkyl substances in at-harvest corn-plant samples detected two prescription antibiotics, norfloxacin and ciprofloxacin, at concentrations of 36 and 70 ng/g, respectively, in effluent-irrigated corn-plant samples; no contaminants were detected in noneffluent irrigated corn-plant samples.

Characterization of vitellogenin concentration in male fathead minnow mucus compared to plasma, and liver mRNA

The objective of this study was to characterize vitellogenin (VTG) protein in male fathead minnow (Pimephales promelas) mucus compared with more conventional measures in plasma and mRNA isolated from liver. To assess the intensity and duration of changes in mucus VTG concentrations, male fathead minnows were exposed to 17α-ethinylestradiol (EE2) for 7 days with a subsequent depuration period of 14 days. The experiment was conducted in a flow-through system to maintain a consistent concentration of EE2 at a nominal EC₅₀ concentration of 2.5 ng/L and high concentration of 10 ng/L as a positive control. Mucus, plasma and liver were sampled at regular intervals throughout the study. Relative abundance of vtg mRNA increased after 2 days of exposure and returned to control levels after 4 days of depuration. VTG protein concentration displayed similar induction kinetics in both mucus and plasma, however, it was found to be significantly increased after 2 days of exposure using the mucus-based assays and 7 days with the plasma-based assay. Significantly elevated levels of VTG were detected by both assays throughout the 14-day depuration period. The elimination of the laborious plasma collection step in the mucus-based workflow allowed sampling of smaller organisms where blood volume is limiting. It also resulted in significant gains in workflow efficiency, decreasing sampling time without loss of performance.

Environmental risk assessment of pharmaceuticals at a seasonal holiday destination in the largest freshwater shallow lake in Central Europe

The presence of pharmacologically active compounds (PhACs) in surface waters poses an environmental risk of chronic exposure to nontarget organisms, which is a well-established and serious concern worldwide. Our aim was to determine the temporal changes in ecological risk quotient (RQ) based on the concentrations of 42 PhACs from six sampling sites on seven sampling dates in the water of a freshwater lake in Central Europe preferentially visited by tourists. Our hypothesis was that the environmental risk increases during the summer holiday season due to the influence of tourists. Different experimental toxicological threshold concentrations and seasonal measured environmental concentrations of 16 PhACs were applied to ecological risk assessment. RQs of 4 dominant PhACs (diclofenac, estrone [E1], estradiol [E2], and caffeine) indicated high ecological risk (RQ > 1) for freshwater ecosystems. Additionally, our results confirmed the assumptions that the high tourist season had a significant impact on the calculated RQ; however, these results are mainly due to the concentration and temporal change of particular PhACs, including diclofenac (5.3-419.4 ng/L), E1 (0.1-5.5 ng/L), and E2 (0.1-19.6 ng/L). The seasonal dependent highest RQs changed as follows: 9.80 (June 2017; E2), 1.23 (August 2017; E1), 0.43 (November 2017; E1), 0.51 (April 2018; E1), 5.58 (June 2018, diclofenac), 39.50 (August 2018; diclofenac), and 30.60 (October 2018; diclofenac).

Evaluation of the oestrogenic potential of oestrone and bisphenol-A on the reproduction of Astyanax bimaculatus males after subacute exposure

In the last decades, oestrogenic compounds have often been reported in environmentally relevant concentrations in aquatic environments around the world. Most laboratory studies of oestrogens try to understand the effects of a single contaminant, but in natural environments, the effects may be quite different due to interactions with other compounds. The present study aimed to compare the action of oestrone (E1) and bisphenol-A (BPA), acting singularly and in combination, on the spermatogenesis of Astyanax bimaculatus. After exposure to 100 ng/L of E1, BPA and a mixture of the two for 15 days, our results showed that E1 and the E1 + BPA mixture significantly altered the number of spermatogenic cells. BPA presented high cytotoxicity when compared to other treatments. Analysis of the two oestrogenic compounds suggests that the E1 + BPA mixture has no additive or synergistic effects. Together, the results of the present study indicate that endocrine-disrupting chemicals (EDCs) analysed alone may behave differently than when administered with other substances.

Effects of Wastewater Treatment Plant Effluent in a Receiving Stream on Reproductive Behavior of Fathead Minnows (Pimephales promelas)

Wastewater treatment plant effluents contain a variety of endocrine disrupting chemicals (EDCs), including chemicals with estrogenic activity such as 17β-estradiol (E2), 17α-ethinyl estradiol (EE2), and nonylphenols. These substances can affect both behavior and physiology in vertebrate animals. To explore the presence and effects of these EDCs in a natural setting, juvenile and adult male fathead minnows, Pimephales promelas, were held in cages upstream and downstream of the effluent site of a wastewater treatment plant for 21 days and subsequently tested for changes in reproductive behaviors and production of vitellogenin. Additionally, estrogenic activity in the stream was measured using a yeast bioassay. Estrogenicity was found to be significantly higher downstream of the wastewater effluent when compared to levels upstream. Vitellogenin levels did not show a correlational pattern with levels of estrogenicity in the water, but two measures of reproductive behaviors occurred significantly less often in downstream males than upstream males. This suggests that a brief (three-week) exposure to stream water containing wastewater treatment plant effluent can bring about changes in reproductive behavior of fish and that behavior may be more sensitive to low levels of environmental endocrine disruptors than vitellogenin production.

Application of an Effects-Based Monitoring Strategy to Assess the Impact of Contaminants on Fish Health in an Urbanized Watershed

Effects-based monitoring frameworks that combine the use of analytical chemistry with in vitro cell bioassays, as well as in vivo whole organism tests offer an integrative approach to broadly screen for chemical contaminants and link their presence with adverse effects on aquatic organisms. California (USA) is currently evaluating the use of such a framework to assess the impact of contaminants of emerging concern (CECs) on biota in urbanized rivers and other waterbodies. In the present study, the occurrence and effects of contaminants found in the Los Angeles River (Los Angeles County, CA, USA) were examined using analytical chemistry and in vitro and in vivo bioassays. Male fathead minnows were deployed in field-based exposure units and exposed to river water for 21 d. The 2 field sites (above Bull Creek [BLC] and below Glendale Water Reclamation Plant [GWR]) were selected based on their unique characteristics and different contaminant discharge sources. In addition, 2 control units (filtered city water and estrone-spiked water) were added to the experimental design. Chemical analyses revealed differences in abundance of CECs between the 2 field sites and the controls, with GWR having the highest number and concentrations of CECs and metals. Cell bioassays screening for estrogenic, glucocorticoid, progestin, and dioxin-like activities were near or below detection limits in all river water samples, indicating a low potential for endocrine-related toxicity and tissue damage. Cell bioassay results were corroborated by the in vivo analyses. Field-exposed fish exhibited no changes in plasma hormones (e.g., estradiol), vitellogenin, or gonad maturation, but gene biomarkers of chemical exposure (cytochrome p450 1A and metallothionein) were significantly elevated, confirming exposure of the fish to complex chemical mixtures. The results demonstrate the value of a tiered monitoring approach to assess the sublethal effects of chemical mixtures on aquatic life. Environ Toxicol Chem 2021;40:402-412. © 2020 SETAC.

Estrogenicity of agricultural runoff: A rainfall simulation study of worst-case scenarios using fresh layer and roaster litter, and farrowing swine manure

Scientists have correlated land application of animal wastes as fertilizer with the feminization of fish. Two questions were asked. 1) Under a worst case scenario when animal waste (layer and roaster litter, or farrowing swine slurry) is applied and tilled in 24 h prior to a surface-runoff producing rainfall, will estrogenic equivalents exceed the Lowest Observable Effect Concentration (LOEC) for fish (10 ng/L)? 2) Can calcium concentrations in runoff, measured using a rapid meter-based method, be used as a sentinel of elevated estrogenic activity? In a 3-yr study wastes were surface-applied and incorporated and 24 h later, 1.5 by 3 m plots were subjected to simulated rainfall and again 1 wk. and 3 wk. later. Nutrients in runoff were also measured, and in year 1 total coliforms and E. coli. were assessed. Except for an initial preliminary test run, runoff from all plots and years never exceeded 10 ng/L E2Eq equivalent. Calcium concentrations in runoff were not related to estrogenicity, negating its use as a sentinel marker. Specific estrogens in animal waste and runoff were identified by mass spectrometry with concentrations in runoff dependant on manure source and timing of rainfall. As expected, total coliform and E. coli concentrations in runoff were increased by the application of layer litter. Concentrations of nutrients in runoff would not be expected to result in surface water concentrations higher than guidelines for protection of aquatic species. Animal wastes applied in quantities appropriate for crop nutrient requirements, tilled into the soil surface, in observance of regulations avoiding application within 24 h of a predicted rain event, should not result in estrogen levels of environmental concern.

Optimizing the Growth, Health, Reproductive Performance, and Gonadal Histology of Broodstock Fantail Goldfish (Carassius auratus, L.) by Dietary Cacao Bean Meal

Simple Summary

Recently, the use of medicinal herbs for regulating reproduction has received much attention in aquaculture, as they are safe, effective, biodegradable, and locally available. The data on the use of cacao bean meal as a food supplement for fish are extremely scarce. This study assessed the possible effects of cacao bean meal as a feed supplement on the growth, health status, blood biochemical parameters, antioxidant, immune status, physiological parameters, female reproductive performance, and gonadal histological features of fantail goldfish. The experimental treatments consisted of three levels of cacao bean meal 0, 5, and 10 g kg⁻¹ diet with the sex ratio being four females:two males per replicate. The findings suggested that cacao bean meal can be used as a feed supplement in diets of broodstock fantail goldfish for improving the growth, health status, and female reproductive performance, economic efficiency, and gonadal histological structure.

Abstract

The potential effects of cacao bean meal, Theobroma cacao L., (CBM) on the growth, health status, blood biochemical parameters, antioxidant, immune status, physiological parameters, female reproductive performance, and gonadal histological features of fantail goldfish (Carassius auratus, L.) were evaluated using a complete randomized block design with sex as a block. The trial lasted for 60 days. A total of 54 healthy fantail goldfish (36 broodstock females and 18 broodstock males) were randomly allocated into three treatments with supplementation of three levels of cocoa powder 0, 5, and 10 g kg⁻¹ diet, CBM0, CBM5, and CBM10, respectively, with the sex ratio being four females:two males per replicate. The body weight gain and feed conversion ratio of males were increased in the CBM10 treatment (p < 0.05). The CBM10 diet improved relative feed costs (p < 0.05). Females fed on the CBM10 diet had an increase in the serum level of total protein (p = 0.001). Females fed on a diet supplemented with CBM5 showed a decrease in the serum level of triglyceride compared to females fed on CBM0 and CBM10 diets (p = 0.03). CBM10 diet increased the serum superoxide dismutase (SOD) activity of fish compared to CBM0 and CBM5 diets (p = 0.004). Serum levels of testosterone and estradiol were significantly increased in males fed on the CBM10 diet. The female reproductive performance was improved by CBM supplementation (p < 0.05). Ovarian histology exhibited increased granulation and follicle numbers after dietary CBM supplementation compared to the control treatment. Therefore, cacao bean meal can be used as a feed supplement in the diets of fantail goldfish for improving the growth, health status, and female reproductive performance, economic efficiency, and gonadal histological structure.

Conversion of Estrone to 17β-Estradiol: A Potential Confounding Factor in Assessing Risks of Environmental Estrogens to Fish

Feminization of male fish and the role of endocrine-active chemicals in this phenomenon has been an area of intense study for many years. Estrone (E1), a natural steroid, is found in aquatic environments sometimes at high concentrations relative to the estrogenic steroids 17β-estradiol (E2) and 17α-ethynylestradiol. However, E1 has been less thoroughly studied than E2 or 17α-ethynylestradiol due in part to a relatively lower potency in metabolically limited estrogen receptor (ER) binding/activation assays. Recent evidence suggests that in vivo biotransformation of E1 to E2 may occur in fathead minnows (Pimephales promelas) residing in environments with high concentrations of E1, such as near wastewater treatment plants. The enzymes likely responsible for this biotransformation, 17β-hydroxysteroid dehydrogenases (17βHSDs), have been well characterized in mammals but to a lesser extent in fish species. In the present study, a novel systematic analysis of amino acid sequence data from the National Center for Biotechnology Information database demonstrated that multiple 17βHSD isoforms are conserved across different fish species. Experimentally, we showed that metabolically active hepatic cytosolic preparations from 2 commercially important salmonid species, rainbow trout and lake trout, biotransformed E1 to E2 to a degree sufficient to alter results of competitive ER binding assays. These results from in silico and in vitro analyses indicate that E1 and biotransformation may play a significant role in adverse effects on development and reproduction of a variety of fish species in contaminated aquatic environments. Environ Toxicol Chem 2020;39:2028-2040. Published 2020. This article is a US Government work and is in the public domain in the USA.

Temperature-Dependent Biomarkers of Estrogenic Exposure in a Piscivore Freshwater Fish

The biological effects of endocrine-active compounds and increasing water temperatures as a result of climate change have been studied extensively and independently, but there is a dearth of research to examine the combined effect of these factors on exposed organisms. Recent data suggest that estrogenic exposure and rising ambient temperatures independently impact predator-prey relationships. However, establishing these connections in natural settings is complex. These obstacles can be circumvented if biomarkers of estrogenic exposure in resident fish can predict changes in predator-prey relationships. To test the effects of estrone and temperature, the piscivore bluegill sunfish (Lepomis macrochirus) was exposed for 30 days to estrone at concentrations (90 ± 17.6 ng/L [mean ± standard deviation] and 414 ± 146 ng/L) previously shown to reduce prey-capture success. Exposures were conducted at four temperatures (15 °C, 18 °C, 21 °C, 24 °C) to simulate breeding season ambient temperatures across the natural range of this species. A suite of morphological and physiological biomarkers previously linked to estrogenic exposures were examined. Biomarkers of estrone exposure were more commonly and severely impacted in male fish than in female fish. Notably, the gonadosomatic index was lower and gonads were less mature in exposed males. Additionally, temperature modulated the effects of estrone similarly in males and females with fish exposed at higher temperatures typically exhibiting a decreased morphological index. This study provides evidence that alterations in hepatic function and gonadal function may cause shifts in metabolism and energy allocation that may lead to declining prey capture performance.

Endocrine disruption in western mosquitofish from open and closed aquatic ecosystems polluted by swine farm wastewaters

Swine farm wastewaters (SFWs) are generally discharged either directly into nearby rivers or into fish ponds as a source of fertilizer/food for aquaculture in China. SFWs contain various contaminants including steroid hormones. However, there is an extreme paucity of data on their effects in fish populations. Here we investigated the endocrine disrupting effects of SFWs in G. affinis from 2 rivers (7 sites) and 2 fish ponds (2 sites) receiving SFWs and a reference site in Guangdong Province, China. In this study, a total number of 3078 adult western mosquitofish (Gambusia affinis) were collected and the sex ratio was determined. In addition, secondary sexual characteristics were examined and the transcriptional levels of target genes were analyzed. The results showed the mosquitofish populations had a significant increase in male-to-female ratio from 7 sites (including 2 fish ponds) among the 9 sampling sites. The hemal spines of females were masculinized at most sites while the hemal spines of males were feminized at approximately half of the sites (including 2 fish ponds). Significant reduction in vitellogenin (Vtg) mRNA expression was observed in females from 2 sites (including RS7) while elevated Vtg mRNA expression was noticed in males from 2 sites along the rivers (including RS7). Redundancy analysis showed that androgens in the water samples were closely related with male-to-female ratio in the mosquitofish populations and the masculinized hemal spines of females. The findings from this study demonstrated that discharge of SFWs could result in occurrence of both masculinized females and feminized males in mosquitofish population.

Land Use Contributions to Adverse Biological Effects in a Complex Agricultural and Urban Watershed: A Case Study of the Maumee River

Agricultural and urban contaminants are an environmental concern because runoff may contaminate aquatic ecosystems, resulting in stress for exposed fish. The objective of the present controlled, field-based study was to assess the impacts of high-intensity agriculture and urban land use on multiple life stages of the fathead minnow (Pimephales promelas), using the Maumee River (Toledo, OH, USA) as a case study. Laboratory cultured adult and larval fathead minnows were exposed for 21 d, and embryos were exposed until hatching to site-specific water along the lower reach of the Maumee River. Adult minnows were analyzed for reproduction and alterations to hematologic characteristics (vitellogenin, glucose, estradiol, 11-ketotestosterone). Water and fish tissue samples were analyzed for a suite of multiresidue pesticides, hormones, and pharmaceuticals. Contaminants were detected in every water and tissue sample, with 6 pesticides and 8 pharmaceuticals detected in at least 82% of water samples and at least half of tissue samples. Effects differed by exposed life stage and year of exposure. Fecundity was the most sensitive endpoint measured and was altered by water from multiple sites in both years. Physiological parameters associated with fecundity, such as plasma vitellogenin and steroid hormone concentrations, were seldom impacted. Larval fathead minnows appeared to be unaffected. Embryonic morphological development was delayed in embryos exposed to site waters collected in 2016 but not in 2017. A distinction between agricultural and urban influences in the Maumee River was not realized due to the great overlap in contaminant presence and biological effects. Differences in precipitation patterns between study years likely contributed to the observed biological differences and highlight the need for environmental exposure studies to assess the environmental risk of contaminants. Environ Toxicol Chem 2019;00:1-17. © 2019 SETAC.

Multiplex Analysis Platform for Endocrine Disruption Prediction Using Zebrafish

Small fish are an excellent experimental model to screen endocrine-disrupting compounds, but current fish-based assays to detect endocrine disruption have not been standardized yet, meaning that there is not consensus on endpoints and biomarkers to be measured. Moreover, exposure conditions may vary depending on the species used as the experimental model and the endocrine pathway evaluated. At present, a battery of a wide range of assays is usually needed for the complete assessment of endocrine activities. With the aim of providing a simple, robust, and fast assay to assess endocrine-disrupting potencies for the three major endocrine axes, i.e., estrogens, androgens, and thyroid, we propose the use of a panel of eight gene expression biomarkers in zebrafish larvae. This includes brain aromatase (cyp19a1b) and vitellogenin 1 (vtg1) for estrogens, cytosolic sulfotransferase 2 family 2 (sult2st3) and cytochrome P450 2k22 (cyp2k22) for androgens, and thyroid peroxidase (tpo), transthyretin (ttr), thyroid receptor α (trα), and iodothyronine deiodinase 2 (dio2) for thyroid metabolism. All of them were selected according to their responses after exposure to the natural ligands 17β-estradiol, testosterone, and 3,3',5-triiodo-L-thyronine (T3), respectively, and subsequently validated using compounds reported as endocrine disruptors in previous studies. Cross-talk effects were also evaluated for all compounds.

Gonadosomatic index as a confounding variable in fish-based screening assays for the detection of anti-estrogens and nonaromatizable androgens

The presence of reproductive endocrine-disrupting compounds (REDCs) in the environment poses a potential threat to fish and wildlife, because exposures are capable of altering sexual development, reproductive success, and behavior. Fish-based screening assays are often utilized to screen for the presence of REDCs in surface waters and to assess single chemicals for potential endocrine-disrupting activity. In an effort to improve such screening assays, the goal of the present study was to determine whether the gonadosomatic index (GSI) of female fathead minnows (Pimephales promelas), as assessed via external characteristics, influences their response to REDC exposure. Specifically, we sought to determine whether low-GSI females differed from high-GSI females in their responses to the model anti-estrogen fadrozole and the model androgen 17β-trenbolone, and whether there was a preferable classification in the context of REDC screening. Low-GSI females were more sensitive to fadrozole at the lower concentration of fadrozole (5 µg/L) and to the higher concentration of trenbolone (50 ng/L), whereas high-GSI females were more sensitive at the lower concentration of trenbolone (5 ng/L). The differential response of low- and high-GSI females to REDCs indicates that GSI influences exposure outcome, and should subsequently be taken into consideration in the implementation of screening assays, as failure to utilize fish of the appropriate reproductive status may skew the test results. Environ Toxicol Chem 2019;38:603-615. © 2019 SETAC.

Critical review: Grand challenges in assessing the adverse effects of contaminants of emerging concern on aquatic food webs

Much progress has been made in the past few decades in understanding the sources, transport, fate, and biological effects of contaminants of emerging concern (CECs) in aquatic ecosystems. Despite these advancements, significant obstacles still prevent comprehensive assessments of the environmental risks associated with the presence of CECs. Many of these obstacles center around the extrapolation of effects of single chemicals observed in the laboratory or effects found in individual organisms or species in the field to impacts of multiple stressors on aquatic food webs. In the present review, we identify 5 challenges that must be addressed to promote studies of CECs from singular exposure events to multispecies aquatic food web interactions. There needs to be: 1) more detailed information on the complexity of mixtures of CECs in the aquatic environment, 2) a greater understanding of the sublethal effects of CECs on a wide range of aquatic organisms, 3) an ascertaining of the biological consequences of variable duration CEC exposures within and across generations in aquatic species, 4) a linkage of multiple stressors with CEC exposure in aquatic systems, and 5) a documenting of the trophic consequences of CEC exposure across aquatic food webs. We examine the current literature to show how these challenges can be addressed to fill knowledge gaps. Environ Toxicol Chem 2019;38:46-60. © 2018 SETAC.

Evaluation of targeted and untargeted effects-based monitoring tools to assess impacts of contaminants of emerging concern on fish in the South Platte River, CO

Rivers in the arid Western United States face increasing influences from anthropogenic contaminants due to population growth, urbanization, and drought. To better understand and more effectively track the impacts of these contaminants, biologically-based monitoring tools are increasingly being used to complement routine chemical monitoring. This study was initiated to assess the ability of both targeted and untargeted biologically-based monitoring tools to discriminate impacts of two adjacent wastewater treatment plants (WWTPs) on Colorado's South Platte River. A cell-based estrogen assay (in vitro, targeted) determined that water samples collected downstream of the larger of the two WWTPs displayed considerable estrogenic activity in its two separate effluent streams. Hepatic vitellogenin mRNA expression (in vivo, targeted) and NMR-based metabolomic analyses (in vivo, untargeted) from caged male fathead minnows also suggested estrogenic activity downstream of the larger WWTP, but detected significant differences in responses from its two effluent streams. The metabolomic results suggested that these differences were associated with oxidative stress levels. Finally, partial least squares regression was used to explore linkages between the metabolomics responses and the chemical contaminants that were detected at the sites. This analysis, along with univariate statistical approaches, identified significant covariance between the biological endpoints and estrone concentrations, suggesting the importance of this contaminant and recommending increased focus on its presence in the environment. These results underscore the benefits of a combined targeted and untargeted biologically-based monitoring strategy when used alongside contaminant monitoring to more effectively assess ecological impacts of exposures to complex mixtures in surface waters.

Contaminants of emerging concern presence and adverse effects in fish: A case study in the Laurentian Great Lakes

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.

Temperature modulates estrone degradation and biological effects of exposure in fathead minnows

Environmental pollutants, including estrogens, are widespread in aquatic environments frequently as a result of treated wastewater effluent discharged. Exposure to estrogens has been correlated with disruption of the normal physiological and reproductive function in aquatic organisms, which could impair the sustainability of exposed populations. However, assessing the effects of estrogen exposure on individuals is complicated by the fact that rates of chemical uptake and environmental degradation are temperature dependent. Because annual temperature regimes often coincide with critical periods of biological activity, temperature-dependent changes in estrogen degradation efficacy during wastewater treatment could modulate biological effects. We examined the interactions between ambient water temperature and degradation of estrone (E1) during wastewater treatment. In addition, we exposed mature fathead minnows (Pimephales promelas) to three environmentally relevant concentrations of E1 at four different water temperatures (15°C, 18°C, 21°C, and 24°C) to reflect natural seasonal variation. E1 degradation occurred with and without the support of robust nitrification at all temperatures; however, the onset of E1 degradation was delayed at cooler water temperatures. In addition, we observed significant interactive effects between temperature and E1 exposure. Female morphometric endpoints were more susceptible to temperature-modulating effects while physiological endpoints were more strongly affected in males. Collectively, the data demonstrate that natural seasonal fluctuations in temperature are sufficient to affect E1 degradation during wastewater treatment and induce sex-dependent physiological and anatomical changes in exposed fish.

Nest-defense behaviors in fathead minnows after lifecycle exposure to the antidepressant venlafaxine

Venlafaxine is an antidepressant and anti-anxiety drug that has been detected in municipal wastewater at low μg/L concentrations. In this study, the nest-defense behavior of adult male fathead minnows (Pimephales promelas) was observed in fish exposed for a full lifecycle to venlafaxine nominal concentrations of 0.88, 8.8, and 88 μg/L (i.e. 1, 9.3, 75 μg/L mean measured concentrations). Nest-defense behaviors quantified were the time taken to contact a dummy intruder fish (on a flexible stick, held near each nest) and the number of contacts made during a 1 min period. In male fathead minnows exposed to venlafaxine over a full lifecycle at environmentally relevant nominal concentrations (i.e. 0.88 and 8.8 μg/L) no significant effects were observed in behavior. However, in males exposed over a full lifecycle to the highest concentration of venlafaxine (i.e. 88 μg/L), nest-defense behaviors were increased in males with empty nests, as shown by the significantly elevated percentage of empty-nest males that made contact with the dummy intruder fish (89%) relative to the lower percentage of contacts (65%) among the Control males (p = 0.046). Lifecycle exposure to high venlafaxine (88 μg/L) caused males to over-protect their empty nests. Environmental venlafaxine concentrations are approximately 70 x lower than this, so it is unlikely that behavioral changes from venlafaxine exposure would occur in the environment. Normal nest defense behaviours in control males varied, depending on whether they were protecting empty nests or nests with eggs. Compared to Control males with empty nests, more Control males with eggs in their nests made contact with the dummy intruder fish (p = 0.014), contact was faster (i.e. <10 s, p = 0.011), and they hit the dummy intruder fish more times in 1 min (p = 0.031) This study is the first to assess reproductive behaviors in fish exposed to an antidepressant over a full lifecycle.

Removal of estrogenic hormones from manure-containing water by vegetable oil capture

Manure-containing water (MCW) is frequently used for agricultural amendment, a practice that introduces natural and synthetic hormones to the environment. Advanced treatment processes are not practical for most animal operations, so inexpensively removing hormones from MCW by capture with vegetable oils was evaluated. Estrone (E1) and 17β-estradiol (E2) were used as model hormones due to their high biological activity and prevalence in MCW. Eight vegetable-based oils were able to remove >94% of E1 and >87% of E2 from nanopure water (NPW), and tested oils had log₁₀K_oil-water values of 1.96-2.66 for E1 and 1.51-2.47 for E2. System parameters were optimized at 3min of shaking time and 1:10 corn oil:water (v/v). Removal from real MCW and NPW was assessed at several initial concentrations of E1 and E2. While E1 removal was comparable across all initial concentrations and both water types (>93%), E2 removal exhibited concentration-dependent interaction with MCW matrix. Treatment capacity was assessed by using the same oil for multiple batches of NPW or MCW. After 18 cycles, removal dropped to 50-64% of E1 and 35-37% for E2. Treating MCW with vegetable oils may be a promising approach to inexpensively remove microcontaminants before MCW is used for land application.

Do environmental factors affect male fathead minnow (Pimephales promelas) response to estrone? Part 2. Temperature and food availability

Fish are subject to constantly changing environmental conditions and food availability, factors that may impact their response to endocrine disruptors (EDs). This may, in part, explain outcome discrepancies between field studies and laboratory exposures to EDs. This study assessed whether standard laboratory conditions for fish exposures adequately represent effects of ED exposure at two environmentally realistic temperatures. The impact of temperature and food availability on male fathead minnow response to estrone (E1) exposure was studied in two experiments (3×2×2 factorial design) with three E1 concentrations (range 0-135ng/L); two temperatures (18°C and 26°C, the latter the prescribed laboratory temperature), and two feeding treatments (full fed vs. 25% of full fed) in a 21-day flow-through system. Morphometric endpoints [including body condition factor, somatic index of gonad (GSI) and liver (HSI), and secondary sex characteristics (SSC)], blood parameters [hematocrit (HCT), blood glucose, cortisol, and vitellogenin (VTG) concentrations], and histology of liver and testis were determined on day 22. High E1 consistently increased VTG, though interactions among E1, temperature and/or food on liver weight, HSI, and HCT were inconsistent between experiments. High temperature impacted the greatest number of parameters, independent of E1 treatment. Three sex-linked parameters were lower at high temperature (testis weight, GSI and VTG), and in Exp. 2SSC and gonad maturity rating were lower. At 26°C, in Exp. 1 HSI and HCT decreased, and in Exp. 2 length, body and liver weight, and body condition factor were lower. Food restriction decreased GSI in Exp. 1, and blood glucose and liver weight in Exp. 2. At 26°C several parameters were altered independent of E1 exposure, including three out of four measurements of sperm differentiation. Concordance between laboratory and field investigations of the biological effects of EDs may improve if environmentally-relevant exposure conditions, especially temperature, are employed.

Estrogenic effects following larval exposure to the putative anti-estrogen, fulvestrant, in the fathead minnow (Pimephales promelas)

The objective of the present study was to investigate the consequences of early-life exposure to fulvestrant on estrogenic gene expression in fathead minnow larvae. To address this objective, fathead minnow larvae were exposed to fulvestrant (ICI 182,780) during the window of sexual differentiation between 0 to 30 days post-hatch (dph). The four treatment groups in this study included: filtered water controls (never exposed), solvent controls (ethanol 0.01%), and nominally low (0.10μg/L) and high (10.0μg/L) doses of fulvestrant. Following 30 d exposure to their respective treatment, larvae were transferred to filtered water aquaria and assessed for alterations in endocrine-responsive gene expression (i.e., RT-qPCR), body size and survival. The remaining fish depurated in filtered water until reaching sexual maturity (180dph) for assessment of persistent effects on sex characteristics, reproductive performance and sex ratio. Following the 30-d early life exposure, larvae showed upregulations of the endocrine-responsive genes ar, erβ and vtg in response to both low and high doses of fulvestrant, but showed no differences in survival or body mass. Upon reaching sexual maturity under depuration conditions, male minnows previously exposed to fulvestrant as larvae showed reductions in gonad mass along with the feminization of secondary sex characteristics with no observed effects in females. Exposure to fulvestrant had no effects on gonadal histology, reproductive performance or final sex ratio as adults. Results from this study demonstrate that aqueous exposure to fulvestrant is estrogenic in fathead minnow larvae and is capable of feminizing male fish as adults following early life exposure.

Do environmental factors affect male fathead minnow (Pimephales promelas) response to estrone? Part 1. Dissolved oxygen and sodium chloride

Laboratory exposures indicate that estrogens and their mimics can cause endocrine disruption in male fishes, yet while studies of resident fish populations in estrogen-polluted waters support these findings, biomarker expression associated with field versus laboratory exposure to estrogenic endocrine disruptors (EDs) often differ dramatically. Two of the environmental parameters often found to vary in dynamic aquatic ecosystems were chosen (dissolved oxygen [DO] and sodium chloride concentrations) to assess their potential impact on ED exposure. In separate experiments, male fathead minnows (Pimephales promelas) were exposed to estrone (E1) a natural ED, under either two concentrations of DO, or two concentrations of sodium chloride, in a laboratory flow-through system. Morphological and hematological parameters were assessed. While vitellogenin concentrations were elevated with exposure to estrone (29 to 390ng/L), the effect on other indices were variable. Estrone exposure altered SSC, blood glucose, hematocrit, and hepatic and gonado-somatic index in 1 of 4 experiments, while it decreased body condition factor in 3 of 4 experiments. At the concentrations tested, no main effect differences (P<0.05) were found associated with DO or sodium chloride treatments, except in one experiment low DO resulted in a decrease in secondary sex characteristic score (SSC). The combination of DO or sodium chloride and E1 altered blood glucose in one experiment each. These results indicate the variability of fathead minnow response to estrone, even within the confines of controlled laboratory conditions.

Social hierarchy modulates responses of fish exposed to contaminants of emerging concern

Many organisms, including the fathead minnow (Pimephales promelas), a toxicological model organism, establish social hierarchies. The social rank of each male in a population is under the control of the hypothalamic-pituitary-gonadal (HPG) axis mainly through regulation of circulating androgen concentrations, which in turn drive the expression of secondary sex characteristics (SSCs). As dominant and subordinate males in an exposure study are initially under different physiological conditions (i.e., differing plasma androgen concentrations), we proposed that they belong to different subpopulations in the context of exposure to compounds that may interact with the HPG axis. Using a meta-analysis of our data from several previously published studies, we corroborated the hypothesis that social status, as indicated by SSCs, results in distinct clusters (eigenvalues >0.8 explaining >80% of variability) with differential expression of plasma vitellogenin, a commonly used biomarker of exposure to contaminants of emerging concern (CEC). Furthermore, we confirmed our predictions that exposure to estrogenic CECs would homogenize plasma vitellogenin response (E1: cluster mean SSC values decreased to 4.33 and 4.86 relative to those of control; E2: decreased to 4.8 and 5.37) across the social hierarchy. In contrast, serotonin-specific reuptake inhibitors expand this response range (cluster mean SSC increased to 5.21 and 6.5 relative to those of control). Our results demonstrated that social hierarchies in male fathead minnows result in heterogeneous responses to chemical exposure. These results represent a cautionary note for the experimental design of single-sex exposure studies. We anticipate our study to be a starting point for the re-evaluation of toxicological data analyses in single sex exposure experiments.

Contaminants of emerging concern in tributaries to the Laurentian Great Lakes: II. Biological consequences of exposure

The Laurentian Great Lakes contain one fifth of the world's surface freshwater and have been impacted by human activity since the Industrial Revolution. In addition to legacy contaminants, nitrification and invasive species, this aquatic ecosystem is also the recipient of Contaminants of Emerging Concern (CECs) with poorly understood biological consequences. In the current study, we documented the presence, concentrations, and biological effects of CECs across 27 field sites in six Great Lakes tributaries by examining over 2250 resident and caged sunfish (Lepomis ssp.) for a variety of morphological and physiological endpoints and related these results to CEC occurrence. CEC were ubiquitous across studies sites and their presence and concentrations in water and sediment were highest in effluent dominated rivers and downstream of municipal wastewater treatment plant discharges. However, even putative upstream reference sites were not free of CEC presence and fish at these sites exhibited biological effects consistent with CEC exposure. Only the Fox River exhibited consistent adverse biological effects, including increased relative liver size, greater prominence of hepatocyte vacuoles and increased plasma glucose concentrations. Canonical Redundancy Analysis revealed consistent patterns of biological consequences of CEC exposure across all six tributaries. Increasing plasma glucose concentrations, likely as a result of pollutant-induced metabolic stress, were associated with increased relative liver size and greater prominence of hepatocyte vacuoles. These indicators of pollutant exposure were inversely correlated with indicators of reproductive potential including smaller gonad size and less mature gametes. The current study highlights the need for greater integration of chemical and biological studies and suggests that CECs in the Laurentian Great Lakes Basin may adversely affect the reproductive potential of exposed fish populations.

Salinity and sensitivity to endocrine disrupting chemicals: A comparison of reproductive endpoints in small-bodied fish exposed under different salinities

The influence of salinity on toxicity outcomes has been demonstrated for various contaminants, but has received limited attention for endocrine disrupting chemicals (EDCs). Short-term laboratory tests using small-bodied fish are an important tool for evaluating impacts of EDCs on reproduction. Tests have been developed for both freshwater and estuarine/marine species, providing an opportunity to assess whether concentrations at which small-bodied fish respond to EDCs may be influenced by salinity. We conducted a semi-quantitative review of short-term laboratory tests with small-bodied fish exposed to EDCs, including 59 studies under freshwater conditions (7 species) and 23 studies conducted under saline conditions (5 species). We focused on two model estrogens [17α-ethinylestradiol and 17β-estradiol (E2)], and three androgens (17β-trenbolone, 5α-dihydrotestosterone and 17α-methyltestosterone). The lowest observed adverse effect concentration (LOAEC_LOW) for key reproductive endpoints was recorded, including sex-steroid and vitellogenin (VTG) levels, fecundity and fertilization. In 65.2% of cases, responses occurred at lower doses under freshwater compared to saline conditions, compared to only 4.3% of cases where fish responded to lower doses under saline conditions. The potential influence of salinity was more pronounced when estrogenic compounds were considered separately, with fish responding to lower doses under fresh compared to saline conditions in 90.5% of cases. Fecundity and E2 level were identified as the most sensitive endpoints for evaluating EDCs regardless of salinity. Interestingly, female VTG levels were a sensitive endpoint under freshwater but not saline conditions. Overall, our results suggest that salinity may be an important factor influencing how small-bodied fish respond to environmental EDCs.

Prioritization of Contaminants of Emerging Concern in Wastewater Treatment Plant Discharges Using Chemical:Gene Interactions in Caged Fish

We examined whether contaminants present in surface waters could be prioritized for further assessment by linking the presence of specific chemicals to gene expression changes in exposed fish. Fathead minnows were deployed in cages for 2, 4, or 8 days at three locations near two different wastewater treatment plant discharge sites in the Saint Louis Bay, Duluth, MN and one upstream reference site. The biological impact of 51 chemicals detected in the surface water of 133 targeted chemicals was determined using biochemical endpoints, exposure activity ratios for biological and estrogenic responses, known chemical:gene interactions from biological pathways and knowledge bases, and analysis of the covariance of ovary gene expression with surface water chemistry. Thirty-two chemicals were significantly linked by covariance with expressed genes. No estrogenic impact on biochemical endpoints was observed in male or female minnows. However, bisphenol A (BPA) was identified by chemical:gene covariation as the most impactful estrogenic chemical across all exposure sites. This was consistent with identification of estrogenic effects on gene expression, high BPA exposure activity ratios across all test sites, and historical analysis of the study area. Gene expression analysis also indicated the presence of nontargeted chemicals including chemotherapeutics consistent with a local hospital waste stream. Overall impacts on gene expression appeared to be related to changes in treatment plant function during rain events. This approach appears useful in examining the impacts of complex mixtures on fish and offers a potential route in linking chemical exposure to adverse outcomes that may reduce population sustainability.

Thermal modulation of anthropogenic estrogen exposure on a freshwater fish at two life stages

Human-mediated environmental change can induce changes in the expression of complex behaviors within individuals and alter the outcomes of interactions between individuals. Although the independent effects of numerous stressors on aquatic biota are well documented (e.g., exposure to environmental contaminants), fewer studies have examined how natural variation in the ambient environment modulates these effects. In this study, we exposed reproductively mature and larval fathead minnows (Pimephales promelas) to three environmentally relevant concentrations (14, 22, and 65ng/L) of a common environmental estrogen, estrone (E1), at four water temperatures (15, 18, 21, and 24°C) reflecting natural spring and summer variation. We then conducted a series of behavioral experiments to assess the independent and interactive effects of temperature and estrogen exposure on intra- and interspecific interactions in three contexts with important fitness consequences; reproduction, foraging, and predator evasion. Our data demonstrated significant independent effects of temperature and/or estrogen exposure on the physiology, survival, and behavior of larval and adult fish. We also found evidence suggesting that thermal regime can modulate the effects of exposure on larval survival and predator-prey interactions, even within a relatively narrow range of seasonally fluctuating temperatures. These findings improve our understanding of the outcomes of interactions between anthropogenic stressors and natural abiotic environmental factors, and suggest that such interactions can have ecological and evolutionary implications for freshwater populations and communities.

In Vitro and In Vivo Assessment of Aqueously Extractable Estrogens in Poultry Manure after Pilot-scale Composting

Poultry manure contains free and conjugated forms of the natural estrogens 17β-estradiol and estrone, which can be transported to receiving waters via runoff when land-applied. Previous studies have demonstrated estrogens in runoff from poultry manure-amended fields but have not tracked changes in estrogenicity within this water over time. Microbial conversion of conjugated estrogens (a major portion of water-extractable estrogens) to parent forms may result in temporary increases in estrogenicity in natural water bodies. The present study created 80-L batches of simulated poultry manure runoff, which were investigated over 10 d for estrogenicity by bioluminescent yeast estrogen screen assay and fathead minnow () vitellogenin induction model. The efficacy of different compost conditions (in-vessel aeration ± turning, and piling) on reduction/elimination of aqueously extractable estrogens in poultry manure was also investigated. Results indicate 3- to 10-fold increases in estrogenicity in various poultry manure mixtures during 10-d observations. Estrogenicity returned to low levels in postcompost treatments but remained elevated in the precompost treatment. Aerated compost resulted in >75% reductions in initial, peak, and 10-d mean estrogenicity in aqueous mixtures (0.3, 0.8, and 0.5 ng 17β-estradiol equivalents [EEQ] L, respectively) compared with the precompost mixture (1.4, 4.8, and 2.1 ng EEQ L, respectively). Estrogenicity was significantly higher in the aqueous extract from the piled treatment than the aerated treatment, and 10-d exposure of male fish to the piled treatment resulted in statistically significant vitellogenin induction. Collectively, our results suggest a need to investigate estrogenicity in surface waters for several days after receiving manure-influenced runoff.

Re-evaluating the Significance of Estrone as an Environmental Estrogen

Studies worldwide have demonstrated the occurrence of feminized male fish at sites impacted by human and animal wastes. A variety of chemicals could contribute to this phenomenon, but those receiving the greatest attention in terms of research and monitoring have been 17β-estradiol (β-E2) and 17α-ethinylestradiol, due both to their prevalence in the environment and strong estrogenic potency. A third steroid, estrone (E1), also can occur at high concentrations in surface waters but generally has been of lesser concern due to its relatively lower affinity for vertebrate estrogen receptors. In an initial experiment, male fathead minnow (Pimephales promelas) adults were exposed for 4-d to environmentally relevant levels of waterborne E1, which resulted in plasma β-E2 concentrations similar to those found in reproductively active females. In a second exposure we used ¹³C-labeled E1, together with liquid chromatography-tandem mass spectrometry, to demonstrate that elevated β-E2 measured in the plasma of the male fish was indeed derived from the external environment, most likely via a conversion catalyzed by one or more 17β-hydroxysteroid dehydrogenases. The results of our studies suggest that the potential impact of E1 as an environmental estrogen currently is underestimated.

Veterinary pharmaceuticals in aqueous systems and associated effects: an update

Environmental studies have shown that pharmaceuticals can contaminate aqueous matrices, such as groundwater, surface water, sediment as well as aquatic flora and fauna. Effluents from sewage and wastewater treatment plants, pharmaceutical industries and hospitals have been implicated in such contamination. Recent studies have however revealed significant concentrations of pharmaceuticals in wastewater from animal facilities in proximal aquatic habitats. Furthermore, epidemiological studies have shown a consistent positive correlation between exposure to some drugs of veterinary importance and increased adverse effects in aquatic biota largely due to induction of endocrine disruption, antibiotic resistance, neurotoxicity, genotoxicity and oxidative stress. The aquatic habitats and associated biota are important in the maintenance of global ecosystem and food chain. For this reason, anything that compromises the integrity and functions of the aquatic environment may lead to major upset in the world's ecosystems. Therefore, knowledge about this route of exposure cannot be neglected and monitoring of their occurrence in the environment is required. This review focuses on scientific evidence that link the presence of pharmaceuticals in aqueous matrices to animal production facilities and presents means to reduce the occurrence of veterinary pharmaceutical residues in the aquatic habitats.

Prior knowledge-based approach for associating contaminants with biological effects: A case study in the St. Croix River basin, MN, WI, USA

Evaluating potential adverse effects of complex chemical mixtures in the environment is challenging. One way to address that challenge is through more integrated analysis of chemical monitoring and biological effects data. In the present study, water samples from five locations near two municipal wastewater treatment plants in the St. Croix River basin, on the border of MN and WI, USA, were analyzed for 127 organic contaminants. Known chemical-gene interactions were used to develop site-specific knowledge assembly models (KAMs) and formulate hypotheses concerning possible biological effects associated with chemicals detected in water samples from each location. Additionally, hepatic gene expression data were collected for fathead minnows (Pimephales promelas) exposed in situ, for 12 d, at each location. Expression data from oligonucleotide microarrays were analyzed to identify functional annotation terms enriched among the differentially-expressed probes. The general nature of many of the terms made hypothesis formulation on the basis of the transcriptome-level response alone difficult. However, integrated analysis of the transcriptome data in the context of the site-specific KAMs allowed for evaluation of the likelihood of specific chemicals contributing to observed biological responses. Thirteen chemicals (atrazine, carbamazepine, metformin, thiabendazole, diazepam, cholesterol, p-cresol, phenytoin, omeprazole, ethyromycin, 17β-estradiol, cimetidine, and estrone), for which there was statistically significant concordance between occurrence at a site and expected biological response as represented in the KAM, were identified. While not definitive, the approach provides a line of evidence for evaluating potential cause-effect relationships between components of a complex mixture of contaminants and biological effects data, which can inform subsequent monitoring and investigation.

Comparison of in vitro estrogenic activity and estrogen concentrations in source and treated waters from 25 U.S. drinking water treatment plants

In vitro bioassays have been successfully used to screen for estrogenic activity in wastewater and surface water, however, few have been applied to treated drinking water. Here, extracts of source and treated water samples were assayed for estrogenic activity using T47D-KBluc cells and analyzed by liquid chromatography-Fourier transform mass spectrometry (LC-FTMS) for natural and synthetic estrogens (including estrone, 17β-estradiol, estriol, and ethinyl estradiol). None of the estrogens were detected above the LC-FTMS quantification limits in treated samples and only 5 source waters had quantifiable concentrations of estrone, whereas 3 treated samples and 16 source samples displayed in vitro estrogenicity. Estrone accounted for the majority of estrogenic activity in respective samples, however the remaining samples that displayed estrogenic activity had no quantitative detections of known estrogenic compounds by chemical analyses. Source water estrogenicity (max, 0.47ng 17β-estradiol equivalents (E2Eq) L^-1) was below levels that have been linked to adverse effects in fish and other aquatic organisms. Treated water estrogenicity (max, 0.078ngE2EqL^-1) was considerably below levels that are expected to be biologically relevant to human consumers. Overall, the advantage of using in vitro techniques in addition to analytical chemical determinations was displayed by the sensitivity of the T47D-KBluc bioassay, coupled with the ability to measure cumulative effects of mixtures, specifically when unknown chemicals may be present.

Molecular initiating events of the intersex phenotype: Low-dose exposure to 17α-ethinylestradiol rapidly regulates molecular networks associated with gonad differentiation in the adult fathead minnow testis

Intersex, or the presence of oocytes in the testes, has been documented in fish following exposure to wastewater effluent and estrogenic compounds. However, the molecular networks underlying the intersex condition are not completely known. To address this, we exposed male fathead minnows to a low, environmentally-relevant concentration of 17alpha-ethinylestradiol (EE2) (15ng/L) and measured the transcriptome response in the testis after 96h to identify early molecular initiating events that may proceed the intersex condition. The short-term exposure to EE2 did not affect gonadosomatic index and proportion of gametes within the testes. However, the production of 11-ketotestosterone and testosterone from the testis in vitro was decreased relative to controls. Expression profiling using a 8×60K fathead minnow microarray identified 10 transcripts that were differentially expressed in the testes, the most dramatic change being that of coagulation factor XIII A chain (20-fold increase). Transcripts that included guanine nucleotide binding protein (Beta Polypeptide 2), peroxisome proliferator-activated receptor delta, and WNK lysine deficient protein kinase 1a, were down-regulated by EE2. Subnetwork enrichment analysis revealed that EE2 suppressed transcriptional networks associated with steroid metabolism, hormone biosynthesis, and sperm mobility. Most interesting was that gene networks associated with doublesex and mab-3 related transcription factor 1 (dmrt1) were suppressed in the adult testis, despite the fact that dmrt1 itself was not different in expression from control males. Transcriptional networks involving forkhead box L2 (foxl2) (transcript involved in ovarian follicle development) were increased in expression in the testis. Noteworthy was that a gene network associated to granulosa cell development was increased over 100%, suggesting that this transcriptome network may be important for monitoring estrogenic exposures. Other cell processes rapidly downregulated by EE2 at the transcript level included glucose homeostasis, response to heavy metal, amino acid catabolism, and the cyclooxygenase pathway. Conversely, lymphocyte chemotaxis, intermediate filament polymerization, glucocorticoid metabolism, carbohydrate utilization, and anterior/posterior axis specification were increased. These data provide new insight into the transcriptional responses that are perturbed prior to gonadal remodeling and intersex following exposure to estrogens. These data demonstrate that low concentrations of EE2 (1) rapidly suppresses male hormone production, (2) down-regulate molecular networks related to male sex differentiation, and (3) induce transcriptional networks related to granulosa cell development in the adult testis. These responses are hypothesized to be key molecular initiating events that occur prior to the development of the intersex phenotype following estrogenic exposures.

Characterization, specificity and sensibility of produced anti-Rhamdia quelen vitellogenin in Brazilian fish species

Endocrine-disrupting chemicals (EDCs) are widespread used and can interfere on hormone regulation with adverse consequences for both biota and human. Vitellogenin (vtg) is a yolk precursor protein synthesized by the liver in response to estrogen. In order to characterize the vtg of tropical fish Rhamdia quelen and establish a molecular biomarker, adult male individuals were exposed to 17-β-estradiol (E₂) for vtg induction and anti-R. quelen vtg polyclonal antibodies production. Vitellogenic female fish were used as positive control group. E₂-induced vtg was characterized as a glycolipophosphoprotein of high molecular mass with peptide mass fingerprint very similar in E₂-exposed male and vitellogenic female fish. A polyclonal serum containing anti-R. quelen vtg antibodies was produced and showed high specificity and sensibility to detect the vtg of three fish species: R. quelen, Piaractus mesopotamicus and Prochilodus lineatus. Wildlife and laboratory studies reported that EDCs released into the environment may alter the levels of plasma vtg in male fish, making this protein a valuable biomarker of xenoestrogens exposure. Then, we propose the use of anti-R. quelen vtg as a tool for biomonitoring studies and water quality assessment in Brazil and South American countries where the three fish species occur.

Interpretation of fish biomarker data for identification, classification, risk assessment and testing of endocrine disrupting chemicals

Chemical induced changes in fish biomarkers vitellogenin (VTG), secondary sex characteristics (SSC), and sex ratio indicate modes/mechanisms of action (MOAs) of EAS (estrogen, androgen and steroidogenesis) pathways. These biomarkers could be used for defining MOAs and the causal link between MOAs and adverse effects in fish for the identification of endocrine disrupting chemicals (EDCs). This paper compiled data sets of 150 chemicals for VTG, 57 chemicals for SSC and 38 chemicals for sex ratio in fathead minnow, medaka and zebrafish. It showed 1) changes in fish biomarkers can indicate the MOAs as anticipated; 2) in addition to EAS pathways, chemicals with non-EAS pathways induced changes in fish biomarkers; 3) responses of fish biomarkers did not always follow the anticipated patterns of EAS pathways. These responses may result from the interaction of chemical-induced multiple MOAs and confounding factors like fish diet, infection, culture conditions, general toxicity and stress response. The complex response of fish biomarkers to a chemical of interest requires EDC testing at multiple biological levels. Interpretation of fish biomarker data should be combined with relevant information at different biological levels, which is critical for defining chemical specific MOAs. The utility of fish biomarker data for identification, classification, PBT assessment, risk assessment, and testing of EDCs in the regulatory context was discussed. This paper emphasizes the importance of fish biomarker data in the regulatory context, a weight of evidence approach for the interpretation of fish biomarker data and the need for defining levels of evidence for the identification of EDCs.

Contaminants of emerging concern in a large temperate estuary

This study was designed to assess the occurrence and concentrations of a broad range of contaminants of emerging concern (CECs) from three local estuaries within a large estuarine ecosystem. In addition to effluent from two wastewater treatment plants (WWTP), we sampled water and whole-body juvenile Chinook salmon (Oncorhynchus tshawytscha) and Pacific staghorn sculpin (Leptocottus armatus) in estuaries receiving effluent. We analyzed these matrices for 150 compounds, which included pharmaceuticals, personal care products (PPCPs), and several industrial compounds. Collectively, we detected 81 analytes in effluent, 25 analytes in estuary water, and 42 analytes in fish tissue. A number of compounds, including sertraline, triclosan, estrone, fluoxetine, metformin, and nonylphenol were detected in water and tissue at concentrations that may cause adverse effects in fish. Interestingly, 29 CEC analytes were detected in effluent and fish tissue, but not in estuarine waters, indicating a high potential for bioaccumulation for these compounds. Although concentrations of most detected analytes were present at relatively low concentrations, our analysis revealed that overall CEC inputs to each estuary amount to several kilograms of these compounds per day. This study is unique because we report on CEC concentrations in estuarine waters and whole-body fish, which are both uncommon in the literature. A noteworthy finding was the preferential bioaccumulation of CECs in free-ranging juvenile Chinook salmon relative to staghorn sculpin, a benthic species with relatively high site fidelity.

Complex mixtures, complex responses: Assessing pharmaceutical mixtures using field and laboratory approaches

Pharmaceuticals are present in low concentrations (<100 ng/L) in most municipal wastewater effluents but may be elevated locally because of factors such as input from pharmaceutical formulation facilities. Using existing concentration data, the authors assessed pharmaceuticals in laboratory exposures of fathead minnows (Pimephales promelas) and added environmental complexity through effluent exposures. In the laboratory, larval and mature minnows were exposed to a simple opioid mixture (hydrocodone, methadone, and oxycodone), an opioid agonist (tramadol), a muscle relaxant (methocarbamol), a simple antidepressant mixture (fluoxetine, paroxetine, venlafaxine), a sleep aid (temazepam), or a complex mixture of all compounds. Larval minnow response to effluent exposure was not consistent. The 2010 exposures resulted in shorter exposed minnow larvae, whereas the larvae exposed in 2012 exhibited altered escape behavior. Mature minnows exhibited altered hepatosomatic indices, with the strongest effects in females and in mixture exposures. In addition, laboratory-exposed, mature male minnows exposed to all pharmaceuticals (except the selective serotonin reuptake inhibitor mixture) defended nest sites less rigorously than fish in the control group. Tramadol or antidepressant mixture exposure resulted in increased splenic T lymphocytes. Only male minnows exposed to whole effluent responded with increased plasma vitellogenin concentrations. Female minnows exposed to pharmaceuticals (except the opioid mixture) had larger livers, likely as a compensatory result of greater prominence of vacuoles in liver hepatocytes. The observed alteration of apical endpoints central to sustaining fish populations confirms that effluents containing waste streams from pharmaceutical formulation facilities can adversely impact fish populations but that the effects may not be temporally consistent. The present study highlights the importance of including diverse biological endpoints spanning levels of biological organization and life stages when assessing contaminant interactions.

Transformation kinetics of trenbolone acetate metabolites and estrogens in urine and feces of implanted steers

Biotransformation of trenbolone acetate metabolites and estrogens derived from animal feeding operations in soils, waste storage systems, and in land applied manure has been well characterized. Yet recent data demonstrate potential for steroid transport into the environment directly from feedyard pens via runoff or airborne particulate matter. Therefore, the objective of this study was to determine steroid transformation rates in beef cattle excreta. Feces and urine were collected from steers recently treated with steroidal implants. Excreta were stored and periodically extracted over 112 d then analyzed for trenbolone acetate metabolites and estrogens by liquid chromatography mass spectrometry. Conjugated steroids were present primarily in urine, and conjugates quickly degraded to free steroid with a half-life of 0.6-1.0 d. The primary trenbolone acetate metabolite, 17α-trenbolone, had a half-life of 5.1-9.5 d. Likewise, 17α-estradiol was the predominant estrogen, with a half-life of 8.6-53 d. Secondary trenbolone metabolites formed from 17α-trenbolone biotransformation were observed at low concentrations less than 10% initial 17α-trenbolone concentrations. Estrone was the primary metabolite of 17α-estradiol and concentrations of estrone exceeded initial 17α-estradiol concentration in all sample types. These results suggest manure-borne steroids are more stable in excreta than in soil microcosms.

Emerging wastewater contaminant metformin causes intersex and reduced fecundity in fish

The occurrence of intersex fish, where male reproductive tissues show evidence of feminization, have been found in freshwater systems around the world, indicating the potential for significant endocrine disruption across species in the ecosystem. Estrogens from birth control medications in wastewater treatment plant effluent have been cited as the likely cause, but research has shown that endocrine disruption is not solely predictable based on hormone receptor interactions. Many other non-hormone pharmaceuticals are found in effluent at concentrations orders of magnitude higher than estrogens, yet there is little data indicating the impacts of these other medications. The widely prescribed anti-diabetic metformin is among the most abundant of pharmaceuticals found in effluent and is structurally dissimilar from hormones. However, we show here that exposing fathead minnows (Pimephales promelas) to a concentration of metformin found in wastewater effluent causes the development of intersex gonads in males, reduced size of treated male fish, and reduction in fecundity for treated pairs. Our results demonstrate that metformin acts as an endocrine disruptor at environmentally relevant concentrations.

Occurrence and Characterization of Steroid Growth Promoters Associated with Particulate Matter Originating from Beef Cattle Feedyards

Studies of steroid growth promoters from beef cattle feedyards have previously focused on effluent or surface runoff as the primary route of transport from animal feeding operations. There is potential for steroid transport via fugitive airborne particulate matter (PM) from cattle feedyards; therefore, the objective of this study was to characterize the occurrence and concentration of steroid growth promoters in PM from feedyards. Air sampling was conducted at commercial feedyards (n = 5) across the Southern Great Plains from 2010 to 2012. Total suspended particulates (TSP), PM10, and PM2.5 were collected for particle size analysis and steroid growth promoter analysis. Particle size distributions were generated from TSP samples only, while steroid analysis was conducted on extracts of PM samples using liquid chromatography mass spectrometry. Of seven targeted steroids, 17α-estradiol and estrone were the most commonly detected, identified in over 94% of samples at median concentrations of 20.6 and 10.8 ng/g, respectively. Melengestrol acetate and 17α-trenbolone were detected in 31% and 39% of all PM samples at median concentrations of 1.3 and 1.9 ng/g, respectively. Results demonstrate PM is a viable route of steroid transportation and may be a significant contributor to environmental steroid hormone loading from cattle feedyards.

Fish multigeneration test with preliminary short-term reproduction assay for estrone using Japanese medaka (Oryzias latipes)

The most potent chemicals potentially causing adverse effects on fish species are estrogens in human waste.Sewage is a source of these estrogens and it is difficult to reduce. In particular, although the bioactivity of estrone is estimated to be about half of that of estradiol, multiple studies report that more than 100 ng l(–1) of estrone can be detected in urban rivers, including discharges from sewage treatment works; approximately two times as high as estradiol. Few studies have been conducted to investigate the long-term effects of estrone on wildlife; therefore, we conducted fish multigeneration test using Japanese medaka (Oryzias latipes). Medaka were exposed to estrone for 27 weeks across three generations in environmentally relevant concentrations, being 5.74, 11.4, 24.0, 47.1 and 91.4 ng l(–1). No effects on reproduction were observed in the first generation; however, a decline in egg production and fertility was observed in the second generation exposed to 91.4 ng l(–1) estrone, which is lower than some known environmental concentrations in urban environments. Furthermore, histopathological abnormalities were observed in the third generation exposed to both 47.1 and 91.4 ng l(–1), suggesting that estrone possibly exerts severe effects on the third or later generations. However, appearances of testis–ova were observed in the second and third generation they were not consistent with actual effects on reproduction, notwithstanding the testis-ovais regarded as the key evidence for endocrine disruption. Accordingly, we consider that qualitative measurement of abnormalities using histopathological observations is required for appropriate evaluation of endocrine disruption.

Pharmaceuticals and personal care products: A critical review of the impacts on fish reproduction

Research in environmental toxicology involving pharmaceuticals and personal care products (PPCPs) has increased greatly over the last 10-15 years. Much research has been focused on the endocrine-disrupting potential of PPCPs, as they relate to negative population impacts of aquatic organisms. This review assesses the current data on the reported effects of PPCPs on fish reproduction with an emphasis on fecundity, a predictor of population effects. Studies of both individual PPCPs and PPCP mixtures are presented. As the majority of individual PPCP studies reviewed demonstrate negative effects on fish fecundity, we relate these findings to detected surface water concentrations of these compounds. Very few studies involving PPCP mixtures have been conducted; however, the need for these types of studies is warranted as fish are most likely exposed to mixtures of PPCPs in the wild. In addition, laboratory and field assessments of wastewater treatment plant (WWTP) effluents, a major source of PPCPs, are reviewed. Much of the data provided from these assessments are variable and do not generally demonstrate negative impacts on reproduction, or the studies are unable to directly associate observed effects with WWTP effluents. Finally, future research considerations are outlined to provide an avenue into understanding how wild populations of fish are affected by PPCPs. These considerations are aimed at determining the adaptation potential of fish exposed to mixtures of PPCPs over multiple generations. As global use of PPCPs continually rises, the need to discern the effects of chronic exposure to PPCPs is greatly increased.

Do laboratory species protect endangered species? Interspecies variation in responses to 17β-estradiol, a model endocrine active compound

Although the effects of estrogens on model laboratory species are well documented, their utility as surrogates for other species, including those listed as endangered, are less clear. Traditionally, conservation policies are evaluated based on model organism responses but are intended to protect all species in an environment. We tested the hypothesis that the endangered Rio Grande silvery minnow (Hybognathus amarus) is more vulnerable to endocrine disruption-as assessed through its larval predator-escape performance, survival, juvenile sex ratios, and whole-body vitellogenin concentration-than the commonly used toxicological model species fathead minnow (Pimephales promelas) and the bluegill sunfish (Lepomis macrochirus). Fish were exposed concurrently for 21 days to the model endocrine active compound (EAC) 17ß-estradiol (E2) at 10 ng E2/L and 30 ng E2/L in a flow-through system using reconstituted water that simulated the physicochemical conditions of the Middle Rio Grande in New Mexico, USA. No significant differences were observed between the fathead and silvery minnow in larval predator-escape response or juvenile sex ratio. Rio Grande silvery minnow survival decreased significantly at day 14 compared with the other two species; by day 21, both cyprinid species (silvery minnow and fathead minnow) exhibited a significant decrease in survival compared with bluegill sunfish, a member of the family Centrarchidae. Male Rio Grande silvery minnow showed a significant increase in whole-body vitellogenin concentration in the 10 ng/L treatment, whereas fathead minnow and bluegill sunfish showed no significant increases in vitellogenin concentrations across treatments. Our study showed response differences to estrogen exposures between the two cyprinid species and further divergence in responses between the families Cyprinidae and Centrarchidae. These results suggest that commonly used laboratory model organisms may be less sensitive to EACs than the endangered Rio Grande silvery minnow. However, this study supports the continued use of surrogate species for the beneficial implementation of water-quality regulations for the protection of threatened and endangered species if phylogenetic relationships are taken into consideration.

Characterization of trenbolone acetate and estradiol metabolite excretion profiles in implanted steers

Exogenous growth promoters have been used in US beef cattle production for over 50 yr. The environmental fate and transport of steroid growth promoters suggest potential for endocrine-disrupting effects among ecological receptors; however, the initial excretion of steroid metabolites from cattle administered growth promoters has not been well characterized. To better characterize excretion of trenbolone acetate and estrogen metabolites, steers were assigned to 1 of the following treatment groups: control, given no implant, or treatment, administered a combination implant (200 mg trenbolone acetate, 40 mg estradiol). Blood, urine, and fecal samples were collected over the course of 112 d following implantation. Samples were extracted and analyzed by liquid chromatography tandem mass spectrometry for trenbolone acetate and estrogen metabolites. In both urine and feces, 17α-trenbolone and 17α-estradiol were the predominant metabolites following implantation. Mean concentrations of 17α-trenbolone and 17α-estradiol in feces of implanted steers were 5.9 ± 0.37 ng/g and 2.7 ± 0.22 ng/g, respectively. A best-fit model is presented to predict 17α-trenbolone and 17α-estradiol excretion from steers receiving implants. The present study provides the first characterization of both trenbolone and estrogen metabolites in excreta from implanted cattle and will help provide estimates of steroid production from feedyards in the United States.