Simultaneous determination of corticosteroids, androgens, and progesterone in river water by liquid chromatography-tandem mass spectrometry

Wastewater reuse and pharmaceutical pollution in agriculture: Uptake, transport, accumulation and metabolism of pharmaceutical pollutants within plants

The presence of pharmaceutical pollutants in water sources has become a growing concern due to its potential impacts on human health and other organisms. The physicochemical properties of pharmaceuticals based on their intended therapeutical application, which include antibiotics, hormones, analgesics, and antidepressants, is quite diverse. Their presence in wastewater, sewerage water, surface water, ground water and even in drinking water is reported by many researchers throughout the world. Human exposure to these pollutants through drinking water or consumption of aquatic and terrestrial organisms has raised concerns about potential adverse effects, such as endocrine disruption, antibiotic resistance, and developmental abnormalities. Once in the environment, they can persist, undergo transformation, or degrade, leading to a complex mixture of contaminants. Application of treated wastewater, compost, manures or biosolids in agricultural fields introduce pharmaceutical pollutants in the environment. As pharmaceuticals are diverse in nature, significant differences are observed during their uptake and accumulation in plants. While there have been extensive studies on aquatic ecosystems, the effect on agricultural land is more disparate. As of now, there are few reports available on the potential of plant uptake and transportation of pharmaceuticals within and between plant organs. This review summarizes the occurrence of pharmaceuticals in aquatic water bodies at a range of concentrations and their uptake, accumulation, and transport within plant tissues. Research gaps on pharmaceutical pollutants' specific effect on plant growth and future research scopes are highlighted. The factors affecting uptake of pharmaceuticals including hydrophobicity, ionization, physicochemical properties (pKa, logKow, pH, Henry's law constant) are discussed. Finally, metabolism of pharmaceuticals within plant cells through metabolism phase enzymes and plant responses to pharmaceuticals are reviewed.

High enrichment factors in chemical analysis of progestins and in bioassays: insights beyond trace levels

Concerns are growing about adverse effects of progestins on biota, even at ultra-trace concentrations. The enrichment factor (EF) from extraction of analytes in environmental samples that is needed for sample pre-concentration can affect not only performance of the analytical method but also the matrix effect. Therefore, the present study aimed to assess the influence of high sample EF on performance of the high-performance liquid chromatography with atmospheric pressure chemical ionization and photoionization coupled with high-resolution mass spectrometry (HPLC-APCI/APPI-HRMS) method for analysis of progestins in waste water treatment plant (WWTP) effluents and surface waters and analysis of (anti-)progestogenic activities measured by (anti-)PR-CALUX bioassays. The results showed that HPLC-APCI/APPI-HRMS coupled with solid-phase extraction and a high EF (33,333 Lwater/Lextract) enabled the detection of more compounds compared to samples with lower sample EF (10,000 Lwater/Lextract). The matrix effect did not increase proportionally compared to lower EFs (10,000 and 16,666 Lwater/Lextract), and lower limits of quantification were achieved in WWTP effluents and surface waters. The results of bioassays have shown that relative EF of 25 Lwater/Lbioassay appears high enough to detect progestogenic activity in treated waste water. Our study is one of the first to provide insights into sample pre-concentration in analysis of progestins and progestogenicity in aquatic environments.

Novel biosensor for high-throughput detection of progesterone receptor-interacting endocrine disruptors

Progesterone receptor (PR)-interacting compounds in the environment are associated with serious health hazards. However, methods for their detection in environmental samples are cumbersome. We report a sensitive activity-based biosensor for rapid and reliable screening of progesterone receptor (PR)-interacting endocrine disrupting chemicals (EDCs). The biosensor is a cell line which expresses nuclear mCherry-NF1 and a green fluorescent protein (GFP)-tagged chimera of glucocorticoid receptor (GR) N terminus fused to the ligand binding domain (LBD) of PR (GFP-GR-PR). As this LBD is shared by the PRA and PRB, the biosensor reports on the activation of both PR isoforms. This GFP-GR-PR chimera is cytoplasmic in the absence of hormone and translocates rapidly to the nucleus in response to PR agonists or antagonists in concentration- and time-dependent manner. In live cells, presence of nuclear NF1 label eliminates cell fixation and nuclear staining resulting in efficient screening. The assay can be used in screens for novel PR ligands and PR-interacting contaminants in environmental samples. A limited screen of river water samples indicated a widespread, low-level contamination with PR-interacting contaminants in all tested samples.

Tracing COVID-19 drugs in the environment: Are we focusing on the right environmental compartment?

The Coronavirus Disease 2019 (COVID-19) pandemic led to over 770 million confirmed cases, straining public healthcare systems and necessitating extensive and prolonged use of synthetic chemical drugs around the globe for medical treatment and symptom relief. Concerns have arisen regarding the massive release of active pharmaceutical ingredients (APIs) and their metabolites into the environment, particularly through domestic sewage. While discussions surrounding this issue have primarily centered on their discharge into aquatic environments, particularly through treated effluent from municipal wastewater treatment plants (WWTPs), one often overlooked aspect is the terrestrial environment as a significant receptor of pharmaceutical-laden waste. This occurs through the disposal of sewage sludge, for instance, by applying biosolids to land or non-compliant disposal of sewage sludge, in addition to the routine disposal of expired and unused medications in municipal solid wastes. In this article, we surveyed sixteen approved pharmaceuticals for treating COVID-19 and bacterial co-infections, along with their primary metabolites. For this, we delved into their physiochemical properties, ecological toxicities, environmental persistence, and fate within municipal WWTPs. Emphasis was given on lipophilic substances with log Kow >3.0, which are more likely to be found in sewage sludge at significant factions (25.2%-75.0%) of their inputs in raw sewage and subsequently enter the terrestrial environment through land application of biosolids, e.g., 43% in the United States and as high as 96% in Ireland or non-compliant practices of sewage sludge disposal in developing communities, such as open dumping and land application without prior anaerobic digestion. The available evidence underscores the importance of adequately treating and disposing of sewage sludge before its final disposal or land application in an epidemic or pandemic scenario, as mismanaged sewage sludge could be a significant vector for releasing pharmaceutical compounds and their metabolites into the terrestrial environment.

Short-term exposure to dexamethasone at environmentally relevant concentrations impairs embryonic development in Cyprinus carpio: Bioconcentration and alteration of oxidative stress-related gene expression patterns

In recent years and as a result of the Covid-19 pandemic, the consumption of dexamethasone (DXE) has increased. This favors that this corticosteroid is highly released in aquatic environments, generating deleterious effects in aquatic organisms. The information on the toxic effects of DXE in the environment is still limited. Thus, the objective of this work was to determine whether DXE at short-term exposure can cause alterations to embryonic development and alteration of oxidative stress-related gene expression patterns in Cyprinus carpio. For this purpose, common carp embryos (2 hpf) were exposed to realistic concentrations of DXE until 96 hpf. Alterations to embryonic development were evaluated at 12, 24, 48, 72 and 96 hpf. In addition, oxidative stress in carp embryos at 72 and 96 hpf was evaluated by cellular oxidation biomarkers (lipoperoxidation level, hydroperoxide and carbonyl protein content) and antioxidant enzymes activities (superoxide dismutase and catalase). Oxidative stress-related gene expression (sod, cat and gpx1) was also evaluated. Our results showed that DXE concentrations above 35 ng/L are capable of producing alterations to embryonic development in 50 % of the embryo population. Furthermore, DXE was able to induce alterations such as scoliosis, hypopigmentation, craniofacial malformations, pericardial edema and growth retardation, leading to the death of half of the population at 50 ng/L of DXE. Concerning oxidative stress, the results demonstrated that DXE induce oxidative damage on the embryos of C. carpio. In conclusion, DXE is capable of altering embryonic development and generating oxidative stress in common carp C. carpio.

Are synthetic glucocorticoids in the aquatic environment a risk to fish?

The glucocorticosteroid, or glucocorticoid (GC), system is largely conserved across vertebrates and plays a central role in numerous vital physiological processes including bone development, immunomodulation, and modification of glucose metabolism and the induction of stress-related behaviours. As a result of their wide-ranging actions, synthetic GCs are widely prescribed for numerous human and veterinary therapeutic purposes and consequently have been detected extensively within the aquatic environment. Synthetic GCs designed for humans are pharmacologically active in non-mammalian vertebrates, including fish, however they are generally detected in surface waters at low (ng/L) concentrations. In this review, we assess the potential environmental risk of synthetic GCs to fish by comparing available experimental data and effect levels in fish with those in mammals. We found the majority of compounds were predicted to have insignificant risk to fish, however some compounds were predicted to be of moderate and high risk to fish, although the dataset of compounds used for this analysis was small. Given the common mode of action and high level of inter-species target conservation exhibited amongst the GCs, we also give due consideration to the potential for mixture effects, which may be particularly significant when considering the potential for environmental impact from this class of pharmaceuticals. Finally, we also provide recommendations for further research to more fully understand the potential environmental impact of this relatively understudied group of commonly prescribed human and veterinary drugs.

Pharmaceutical compounds used in the COVID-19 pandemic: A review of their presence in water and treatment techniques for their elimination

During the COVID-19 pandemic, high consumption of antivirals, antibiotics, antiparasitics, antiprotozoals, and glucocorticoids used in the treatment of this virus has been reported. Conventional treatment systems fail to efficiently remove these contaminants from water, becoming an emerging concern from the environmental field. Therefore, the objective of the present work is to address the current state of the literature on the presence and removal processes of these drugs from water bodies. It was found that the concentration of most of the drugs used in the treatment of COVID-19 increased during the pandemic in water bodies. Before the pandemic, Azithromycin concentrations in surface waters were reported to be in the order of 4.3 ng L-1, and during the pandemic, they increased up to 935 ng L-1. Laboratory scale studies conclude that adsorption and advanced oxidation processes (AOPs) can be effective in the removal of these drugs. Up to more than 80% removal of Azithromycin, Chloroquine, Ivermectin, and Dexamethasone in aqueous solutions have been reported using these processes. Pilot-scale tests achieved 100% removal of Azithromycin from hospital wastewater by adsorption with powdered activated carbon. At full scale, treatment plants supplemented with ozonation and artificial wetlands removed all Favipiravir and Azithromycin, respectively. It should be noted that hybrid technologies can improve removal rates, process kinetics, and treatment cost. Consequently, the development of new materials that can act synergistically in technically and economically sustainable treatments is required.

Automation in quantifying phenoxy herbicides and bentazon in surface water and groundwater using novel solid phase extraction and liquid chromatography tandem mass spectrometry

The occurrence of phenoxy herbicides is a financial and regulatory concern for drinking water treatment plants. This paper presents a new method of quantification for nine phenoxy-acids and bentazon in different water samples using liquid chromatography tandem mass spectrometry (LC-MS/MS). The method is based on an automated solid phase extraction (SPE) process that applied hydrophilic modified polystyrene and divinylbenzene cartridges at low pH (<2.0). Main advantages of the presented method include the reduced consumption of organic solvent in extraction and the fully automated sample pre-concentration. The method is thus more environmentally-friendly. In the quantification step, five stable isotopically labelled analogues were used as internal standards to account for the losses during sample preparation and to calibrate the ion source response under the mass spectrometric detection. The method was optimized in terms of sample preparation and subsequent LC-MS/MS separation to obtain reliable measurement of the analyte concentration during real sample analysis. The method quantification limit was between 1.5 and 10.0 ng/L for target compounds in surface water and groundwater samples. The method was validated at three fortification levels between 10.0 and 1000 ng/L, and the results showed fit-for-purpose recovery with appropriate precision at low concentration levels. The method was also utilized to analyse thirty-two actual water samples from different sources. Forty percent of the analysed samples contained detectable level of herbicides, ranging from 1.91 to 40.5 ng/L. The concentrations of targeted herbicides in our study were comparable to those found in water samples in other regions of world.

Occurrence, Fate, Effects, and Risks of Dexamethasone: Ecological Implications Post-COVID-19

The recent outbreak of respiratory syndrome-coronavirus-2 (SARS-CoV-2), which causes coronavirus disease (COVID-19), has led to the widespread use of therapeutics, including dexamethasone (DEXA). DEXA, a synthetic glucocorticoid, is among the widely administered drugs used to treat hospitalized COVID-19 patients. The global COVID-19 surge in infections, consequent increasing hospitalizations, and other DEXA applications have raised concerns on eminent adverse ecological implications to aquatic ecosystems. Here, we aim to summarize published studies on DEXA occurrence, fate, and effects on organisms in natural and engineered systems as, pre-COVID, the drug has been identified as an emerging environmental contaminant. The results demonstrated a significant reduction of DEXA in wastewater treatment plants, with a small portion, including its transformation products (TPs), being released into downstream waters. Fish and crustaceans are the most susceptible species to DEXA exposure in the parts-per-billion range, suggesting potential deleterious ecological effects. However, there are data deficits on the implications of DEXA to marine and estuarine systems and wildlife. To improve DEXA management, toxicological outcomes of DEXA and formed TPs should entail long-term studies from whole organisms to molecular effects in actual environmental matrices and at realistic exposure concentrations. This can aid in striking a fine balance of saving human lives and protecting ecological integrity.

Steroid hormones in the aquatic environment

Steroid hormones are extremely important natural hormones in all vertebrates. They control a wide range of physiological processes, including osmoregulation, sexual maturity, reproduction and stress responses. In addition, many synthetic steroid hormones are in widespread and general use, both as human and veterinary pharmaceuticals. Recent advances in environmental analytical chemistry have enabled concentrations of steroid hormones in rivers to be determined. Many different steroid hormones, both natural and synthetic, including transformation products, have been identified and quantified, demonstrating that they are widespread aquatic contaminants. Laboratory ecotoxicology experiments, mainly conducted with fish, but also amphibians, have shown that some steroid hormones, both natural and synthetic, can adversely affect reproduction when present in the water at extremely low concentrations: even sub-ng/L. Recent research has demonstrated that mixtures of different steroid hormones can inhibit reproduction even when each individual hormone is present at a concentration below which it would not invoke a measurable effect on its own. Limited field studies have supported the conclusions of the laboratory studies that steroid hormones may be environmental pollutants of significant concern. Further research is required to identify the main sources of steroid hormones entering the aquatic environment, better describe the complex mixtures of steroid hormones now known to be ubiquitously present, and determine the impacts of environmentally-realistic mixtures of steroid hormones on aquatic vertebrates, especially fish. Only once that research is completed can a robust aquatic risk assessment of steroid hormones be concluded.

A critical review on environmental presence of pharmaceutical drugs tested for the covid-19 treatment

On March 11, 2020, the World Health Organization (WHO) declared COVID-19 a pandemic. The outbreak caused a worldwide impact, becoming a health threat to the general population and its professionals. To date, there are no specific antiviral treatments or vaccines for the COVID-19 infection, however, some drugs are being clinically tested. The use of these drugs on large scale raises great concern about their imminent environmental risk, since the elimination of these compounds by feces and urine associated with the inefficiency of sewage treatment plants in their removal can result in their persistence in the environment, putting in risk the health of humans and of other species. Thus, the goal of this work was to conduct a review of other studies that evaluated the presence of the drugs chloroquine, hydroxychloroquine, azithromycin, ivermectin, dexamethasone, remdesivir, favipiravir and some HIV antivirals in the environment. The research indicated the presence of these drugs in the environment in different regions, with concentration data that could serve as a basis for further comparative studies following the pandemic.

COVID-19 Treatment Agents: Do They Pose an Environmental Risk?

The end of 2019 was marked by reports of a previously unknown virus causing coronavirus disease 19 (COVID-19). With over 800 new daily hospitalizations at the peak in Los Angeles (LA) County, the potential for high use of COVID-19 treatment agents, remdesivir and dexamethasone, warranted a screening assessment of their fate and toxicity risk for aquatic organisms. We predicted environmental concentrations (PECs) using the ChemFate model and hospitalizations data and compared them to predicted ecotoxicity concentrations generated using Ecological Structure Activity Relationships (ECOSAR) to assess risk to potentially exposed organisms. The lowest predicted toxicity thresholds were between 2 and 11 orders of magnitude greater than the highest PECs for freshwater and saltwater. We conclude that had all eligible patients in LA County been given the recommended treatment regimen, exposure of aquatic organisms in regional water bodies to remdesivir, dexamethasone, and their evaluated metabolites would not be likely to be affected based on ECOSAR predictions. Conservative, protective assumptions were used for this screening analysis, considering limited toxicity information. Modeling tools thus serve to predict environmental concentrations and estimate ecotoxicity risks of novel treatment agents and can provide useful preliminary data to assess and manage ecological health risks.

How much do human and livestock actually contribute to steroids emission and surface water pollution from past to the future: A global research

A comprehensive global inventory of past, present, and future steroid emissions was firstly developed based on the global 5' × 5' grids relevant data available. From 1970 to 2070, the growth rate of the annual global steroid emission was relatively stable around 10%. At present (in 2015), the global steroid emissions was 18,270 t, with 17% contributed by humans. Almost one-third of total animal emissions have been occurring in India and Brazil. India also had the highest value of human steroid emissions. Regions with highest steroid emissions were concentrated between 10° ~ 35° N and 70° ~ 90° E. The increase of sewage treatment rates can effectively reduce the total quantity of steroids entering the environment, especially for some developing countries. But the "technology bonus" from sewage treatment process will be exhausted until to 2030. Meanwhile, global surface water pollution was predicted based on steroid emissions into water compartment and on the digital river network with annual river discharge. The modelling results show that steroids are widely distributed across the globe, with concentrations mostly below 100 ng/L. However, if no proper treatment measures for animal excretions, in another 100 years, the range of the surface water contaminated by steroids will increase by 1.2 times. The Nile River resulted as the most polluted among the eight world's longest and famous rivers during the whole period investigated. Various measured concentrations worldwide validated our modelling result. The global steroid emission inventory and surface water pollution from past to the future will stand as an important data and knowledge base for the management of pollution from different types of steroids at global and regional level.

Sodium dodecyl sulfate-multi-walled carbon nanotubes-coated-membrane solid phase extraction of glucocorticoids in aqueous matrices

A membrane-based solid phase extraction (SPE)-ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed for the determination of nine glucocorticoids in water. This new hybrid SPE approach involved the deposition of sodium dodecyl sulfate (SDS)-multi-walled carbon nanotubes (MWCNTs) on a piece of polypropylene membrane that served as the extraction device. Hitherto, such a sample preparation procedure has not been applied to the analysis of water contaminants before. The use of the surfactant helped to disperse the MWCNTs effectively so that they were coated uniformly onto the polypropylene membrane. This increased the overall extraction efficiency of the procedure. Characterisation of the SDS-MWCNTs material was performed using transmission electron microscopy and scanning electron microscopy. The membrane device did not require a pre-conditioning step. The most favourable extraction parameters such as type of surfactant, percentage of surfactant, type of desorption solvent, stirring rate, desorption time, extraction time, temperature, salting-out effect, pH and diameter of MWCNTs were obtained. The method showed linearity ranges from 0.2 to 100 ng mL^-1 for hydrocortisone, dexamethasone, cortisone acetate and beclomethasone dipropionate, and 0.5-100 ng mL^-1 for the rest of the analytes. Limits of detection ranging from 0.019 to 0.098 ng mL^-1, and limits of quantification ranging from 0.065 to 0.326 ng mL^-1, were obtained for the analytes. The intra-day repeatability was between 1.77 and 3.56% while the inter-day reproducibility was between 2.69 and 9.53%, respectively. The method was used to analyse glucocorticoids as contaminants in the canal water samples.

An antibody-aptamer sandwich cathodic photoelectrochemical biosensor for the detection of progesterone

The progesterone (P4) level in body fluids can act as an indicator for early pregnancy diagnosis and offers insight into mammalian somatic function. In this work, we designed an antibody-aptamer based sandwich assay as a cathodic photoelectrochemical (PEC) biosensor for P4 detection. The composites of carbon dots and graphene oxide (CDs-GO) with favorable cathodic photocurrent response were used as photoactive materials on which the antibody (Ab) of P4 was immobilized. Meanwhile, high affinity truncated P4 aptamer was immobilized on Au-CuO-Cu₂O to act as a bioconjugate. When P4 was present, the aptamer-Au-CuO-Cu₂O bioconjugate could amplify the cathodic photocurrent of CDs-GO modified electrode through Ab-P4-aptamer interactions. Under optimum conditions, the cathodic photocurrent of the constructed PEC biosensor was found to increase linearly with P4 in a wide concentration range from 0.5 nM to 180 nM, with a low detection limit (3S/N) of 0.17 nΜ. The proposed cathodic PEC sensing platform demonstrated high selectivity, satisfying reproducibility, good stability. The sensor was successfully applied in the determination of P4 in human serum samples.

Spatiotemporal distribution, source apportionment, and ecological risk of corticosteroids in the urbanized river system of Guangzhou, China

We investigated the occurrence and distribution of 24 selected corticosteroids (CSs) in the surface water of the Zhujiang River (ZR) system in Guangzhou, a highly urbanized river system receiving both treated and untreated municipal wastewater effluents. Twenty-two and sixteen CSs were detected in the tributaries and the main stream of the ZR system, and their concentrations ranged from less than the method quantification limit (fluticasone propionate) to 94 ng/L (clobetasone butyrate) and from 0.24 ng/L (cortisol) to 7.2 ng/L (clobetasone butyrate), respectively. We observed higher total CSs (∑CSs) concentrations in the tributaries (11-396 ng/L) relative to the main stream (5.5-33 ng/L) due to their proximity to densely populated residential areas. ∑CSs concentrations in the dry season were generally higher than those in the wet season due to low dilution from decreased river discharge. Principal component analysis and multiple linear regression analysis identified untreated domestic sewage to be the dominant source of CSs (t₂, contribution rate: 42.7%) in the urban rivers. Additional source contributions were from naturally attenuated treated and/or raw sewage (t₁, 21.5%) and effluents from wastewater treatment plants (t₃, 26.7%). CSs contribution was dominated by t₂ in the dry season, and the contributions from t₁, t₂, and t₃ showed no significant difference in the wet season. Risk assessment inferred that the ZR system is at medium to high ecological risk from CSs and is therefore a potential threat to the health of aquatic ecosystems. To prevent CSs pollution, our results demonstrate the need to develop effective control strategies to minimize the discharge of untreated waste to nearby rivers and to improve the capacity of wastewater treatment plants in Guangzhou. Further, we demonstrate that the concentrations of cortisone and fludrocortisone acetate are effective chemical indicators to estimate the level of natural and synthetic CSs contamination in urban rivers.

Determination and occurrence of natural and synthetic glucocorticoids in surface waters

Glucocorticoids (GCs) have been increasingly reported to have adverse effects on aquatic organisms, but the lack of comprehensive analytical methods for a broad number of GCs has limited the effective management of pollution by these molecules in surface and coastal waters. In this study, we developed an original analytical method for simultaneously monitoring 25 natural GCs, and 43 synthetic GCs (4 hydrocortisone types, 6 acetonide types, 8 betamethasone types, 14 halogenated esters, and 11 labile prodrug esters) in water samples. Of the river samples investigated, 15 natural and 25 synthetic compounds were detected with the concentrations ranging from 0.13 ng/L (11-epitetrahydrocortisol) to 433 ng/L (cortisone) and from 0.05 (clobetasol) to 94 ng/L (prednisolone), respectively. Thirteen natural metabolites of cortisol (CRL) were first detected, and their concentrations were up to 36 times higher than that of CRL. Hydrocortisone-type GCs were the dominant synthetic compounds (≤154 ng/L), followed by halogenated esters (≤81 ng/L), acetonide type GCs (≤57 ng/L), betamethasone type GCs (≤32 ng/L), and labile prodrug esters (≤22 ng/L). Considering the relative potencies for detected GCs compared to dexamethasone, halogenated esters predominantly contributed to the GC activities in the samples. Notably, this is the first report of the halogenated esters 11-oxo fluticasone propionate (OFP) and cloticasone propionate (CTP) in environmental waters. Untreated wastewater is the main source of GCs in the studied waters, and the concentration ratios between natural and synthetic GCs can be used as potential indicators of sewage input. Because of the high detected concentrations and bioactivity potency of halogenated GCs, they are the main contributors to GC activities in the studied waters, and deserved more study in the future.

Occurrence, distribution, and potential risks of environmental corticosteroids in surface waters from the Pearl River Delta, South China

The occurrence, spatiotemporal distribution, and potential risks of 21 glucocorticoids (GCs) and 3 mineralocorticoids (MCs) in four rivers were studied by investigating the surface waters from the Pearl River Delta (PRD), South China. These environmental corticosteroids (ECs) were commonly present in the river surface waters with average concentrations varying from <0.17 ng/L for fluticasone propionate to 5.6 ng/L for clobetasone butyrate; and cortisone had the highest concentration, 32.9 ng/L. The total ECs ranged in concentration from undetectable to 83.3 ng/L, with a mean and median of 8.1 ng/L and 4.8 ng/L, respectively. Spatially the total EC concentration levels in the Pearl River system occurred in the following order: Zhujiang River (ZR) > Dongjiang River (DR) > Shiziyang waterway (SW) > Beijiang River (BR). These levels generally demonstrated a trend of increasing from upstream to midstream or downstream then attenuating toward the estuary. Considerable seasonal variations in the ECs differed among rivers. Higher ECs concentrations in winter were mostly found in the ZR, whereas lower levels were found in the DR. Moreover, the temporal variations of the ECs were marginal in the BR and SW. These spatiotemporal distributions of the ECs might have been simultaneously influenced by pollution sources derived from anthropogenic activities and river hydrologic conditions. Correlation analyses indicated that dissolved organic carbon (DOC) could play a key role in the occurrence and distribution of ECs in an aquatic environment. Risk assessment demonstrated that the occurrence of ECs might have posed medium to high risk to aquatic organisms in the Pearl River.

Environmental glucocorticoids corticosterone, betamethasone and flumethasone induce more potent physiological than transcriptional effects in zebrafish embryos

Many glucocorticoids occur in the aquatic environments but their adverse effects to fish are poorly known. Here we investigate effects of the natural glucocorticoid corticosterone and the synthetic glucocorticoids betamethasone and flumethasone in zebrafish embryos. Besides studying the effects of each steroid, we compared effects of natural with synthetic glucocorticoids, used as drugs. Exposure at concentrations of 1 μg/L and higher led to concentration-related decrease in spontaneous muscle contractions at 24 h post fertilization (hpf) and increase in heart rate at 48 hpf. Betamethasone showed a significant increase at 0.11 μg/L in heart rate. Corticosterone also accelerated hatching at 60 hpf at 0.085 μg/L. Transcription of up to 24 genes associated with different pathways showed alterations at 96 and 120 hpf for all glucocorticoids, although with low potency. Corticosterone caused transcriptional induction of interleukin-17, while betamethasone caused transcriptional down-regulation of the androgen receptor, aromatase and hsd11b2, indicating an effect on the sex hormone system. Furthermore, transcripts encoding proteins related to immune system regulation (irg1l, gilz) and fkbp5 were differentially expressed by corticosterone and betamethasone, while flumethasone caused only little effects, mainly alteration of the irg1l transcript. Our study shows that these glucocorticoids caused more potent physiological effects in early embryos than transcriptional alterations in hatched embryos, likely due to increased metabolism in later developmental stages. Thus, these glucocorticoids may be of concern for early stages of fish embryos in contaminated aquatic environments.

Endocrine-disrupting compounds in the Xiangjiang River of China: Spatio-temporal distribution, source apportionment, and risk assessment

Endocrine-disrupting compounds (EDCs) were seasonally investigated in the surface water of the Xiangjiang River (south China) in order to understand their spatio-temporal distribution, source apportionment, and ecological risks. The occurrence of 21 EDCs were determined with liquid chromatography-tandem mass spectrometry in the water samples collected along the river over four seasons, and the results were statistically analyzed. The concentrations of progestagens, androgens, estrogens ranged from not detected (ND) to 98.3 ng L^-1; while the concentrations of alkylphenols ranged from 0.8 to 3.1 × 10³ ng L^-1; and that of caffeine ranged from 0.1 to 49.8 ng L^-1. The detection frequencies of bisphenol A, 4-tert-octylphenol, 4-n-nonylphenol, estrone, and 17β-estradiol were 95-100% during the four sampling campaigns. The seasonal and spatial variation trend of EDCs in the Xiangjiang River was noticeable. The concentration of EDCs in Yueyang section (downstream) was the highest in winter, while the concentration in Yongzhou (upstream) section was the lowest in spring. The concentration of EDCs in the Xiangjiang River was significantly correlated with the levels of the total organic carbon, water temperature, and dissolved oxygen. Source analysis indicated that untreated sewage was the major source of EDCs. Furthermore, the potential risks of EDCs in the surface water to aquatic organisms were assessed with the risk quotient method (European Commission, 2003), and the results indicated the highest ecological risk of 17β-estradiol in the Xiangjiang River.

Trace analysis of corticosteroids (CSs) in environmental waters by liquid chromatography-tandem mass spectrometry

Natural and synthetic corticosteroids (CSs) are a class of steroid hormones which could potentially disturb the corticosteroid signaling pathways in wildlife and humans. In this study, a sensitive and robust analytical method using solid phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for simultaneous analysis of sub-ng/L concentrations of 26 CSs in highly complex natural water matrices. The method performance was validated for WWTP influent, effluent, surface water and finished drinking water. Low practical quantification levels (PQLs) were achieved as 0.008-0.16 ng/L in finished drinking water, 0.019-0.50 ng/L in surface water, 0.047-1.5 ng/L in WWTP effluent, and 0.10-3.1 ng/L in WWTP influent, respectively, with the recoveries ranging from 70% to 130%. The cleanup performance and matrix interferences were also evaluated. This method was then applied to the analysis of target CSs in WWTP influent and effluent samples collected from a local WWTP, as well as surface water downstream of the WWTP outfall, detecting an average summed CS concentration of 744 ng/L in influent, 23.4 ng/L in effluent and 10.9 ng/L in surface water. Four synthetic CSs (triamcinolone acetonide, fluocinolone acetonide, clobetasol propionate, and fluticasone propionate) were found poorly removed in the WWTP. The developed method provides a tool to obtain occurrence data of corticosteroids in environmental waters, which will permit assessing their risk to environmental organisms.

Pharmaceuticals residues in selected tropical surface water bodies from Selangor (Malaysia): Occurrence and potential risk assessments

This study investigated the occurrence of nine pharmaceuticals (amoxicillin, caffeine, chloramphenicol, ciprofloxacin, dexamethasone, diclofenac, nitrofurazone, sulfamethoxazole, and triclosan) and to evaluate potential risks (human health and ecotoxicological) in Lui, Gombak and Selangor (Malaysia) rivers using commercial competitive Enzyme-Linked Immunosorbent Assay (ELISA) kit assays. Physicochemical properties of these rivers showed the surface samples belong to Class II of Malaysian National Water Quality Standards which requires conventional treatment before consumption. All the pharmaceuticals were detected in all three rivers except for triclosan, dexamethasone and diclofenac which were not detected in few of sampling locations in these three rivers. Highest pharmaceutical concentrations were detected in Gombak river in line of being as one of the most polluted rivers in Malaysia. Ciprofloxacin concentrations were detected in all the sampling locations with the highest at 299.88 ng/L. While triclosan, dexamethasone and diclofenac concentrations were not detected in a few of sampling locations in these three rivers. All these nine pharmaceuticals were within the levels reported previously in literature. Pharmaceutical production, wastewater treatment technologies and treated sewage effluent were found as the potential sources which can be related with pharmaceuticals occurrence in surface water samples. Potential human risk assessment showed low health risk except for ciprofloxacin and dexamethasone. Instead, ecotoxicological risk assessment indicated moderate risks were present for these rivers. Nevertheless, results confirmation using instrumental techniques is needed for higher degree of specificity. It is crucial to continuously monitor the surface water bodies for pharmaceuticals using a cost-effective prioritisation approach to assess sensitive sub-populations risk.

Pharmaceutical Mixtures: Still A Concern for Human and Environmental Health

In the present work, recent data on the sources, occurrence and fate of human-use pharmaceutical active compounds (PhACs) in the aquatic environment have been reviewed. Since PhACs and their metabolites are usually present as mixtures in the environment at very low concentrations, a particular emphasis was placed onto the PhACs mixtures, as well as on their short-term and long-term effects against human and environmental health. Moreover, a general overview of the main conventional as well as of the latest trends in wastewaters decontaminant technologies was outlined. Advantages and disadvantages of current processes were also pointed out. It appears that numerous gaps still exist in the current knowledge related to this field of interest, and further studies should be conducted at the global level in order to ensure a more efficient monitorisation of the presence of PhACs and their metabolites into the aquatic environment and to develop new mitigation measures.

Effect-directed analysis (EDA) of Danube River water sample receiving untreated municipal wastewater from Novi Sad, Serbia

The release of a multitude of pollutants from untreated municipal wastewater (UMWW) to surface waters may have adverse effects on aquatic wildlife including endocrine disruption. For effect-directed analysis (EDA), a Danube river water sample downstream of emission of UMWW in Novi Sad, Serbia was extracted on-site and after processing in the lab was subjected to reporter gene assays which revealed pronounced estrogenic (ERα), androgenic (AR) and oxidative stress response (OSR). The sample was fractionated with reversed-phase high performance liquid chromatography (RP-HPLC) collecting thirty fractions at two-minute intervals. Biological analysis identified 5 ERα- and 3 AR-active fractions while none of the fractions showed considerable activity with regards to OSR. It appeared that OSR of parent sample (PS) distributed over all fractions. Chemical analysis of active fractions by LC-MS/MS and LC-HRMS/MS found female reproductive hormones (estrone (E1), estradiol (E2), estriol (E3)) as cause of ERα activity while male reproductive hormones (testosterone, dihydrotestosterone (DHT)) and gestagens (progesterone and medroxyprogesterone) were active in the AR bioassay. Designed chemical mixtures in concentration ratios detected in the active fractions were tested with the bioassays. The identified chemicals quantitatively explained the observed bioactivity with no substantial contribution attributable to xenobiotics. In terms of bioanalytical equivalent concentrations (BEQs), detected chemicals explained 5-159% of ERα-active fraction's biological effect and 31-147% for AR-active fractions. Estradiol and dihydrotestosterone were the compounds dominating the most of the effect in this study. In summary, androgenic compounds were found to be as potent as estrogenic compounds while OSR was found to be the cumulative effect of the mixture of many compounds present in the sample rather than the mixture effect dominated by individual chemicals. The obtained results stress the importance of wastewater treatment plant (WWTP) to minimize the pollutant load from UMWW in order to reduce the risk of endocrine disruption to the aquatic life as well as to improve the status of receiving freshwater ecosystem.

Occurrence of Glucocorticoids, Mineralocorticoids, and Progestogens in Various Treated Wastewater, Rivers, and Streams

In the current study a high sensitive analytical method was developed for the determination of 60 steroids including glucocorticoids (GC), mineralocorticoids (MC), and progestogens (PG) in WWTP effluents and surface water using liquid chromatography with tandem mass spectrometry detection (LC-MS/MS). The limits of quantification (LOQ) ranged between 0.02 ng/L (cortisone) to 0.5 ng/L (drospirenone) in surface water and from 0.05 ng/L (betamethasone) to 5 ng/L (chlormadinone) in treated wastewater. After optimization, the developed method was applied to WWTP effluents, rivers, and streams around Germany. Numerous steroids have been detected during the sampling campaign and predominant analytes from all steroid types were determined. Moreover, the occurrence of dienogest, mometasone furoate, flumethasone pivalate, and the metabolites 6β-hydroxy dienogest, 6β-hydroxy triamcinolone acetonide, 7α-thiomethyl spironolactone, and 11α-hydroxy canrenone is reported for the first time. In addition, this study revealed the ubiquitous presence of topically applied GC monoesters betamethasone propionate, betamethasone valerate, and 6α-methylprednisolone propionate in WWTP effluents and surface water.

Thermally condensed humic acids onto silica as SPE for effective enrichment of glucocorticoids from environmental waters followed by HPLC-HESI-MS/MS

Pristine humic acids (HAs) were thermally condensed onto silica microparticles by a one-pot, inexpensive and green preparation route obtaining a mixed-mode sorbent (HA-C@silica) with good sorption affinity for glucocorticoids (GCs). The carbon-based material, characterized by various techniques, was indeed applied as the sorbent for fixed-bed solid-phase extraction of eight GCs from river water and wastewater treatment plant effluent, spiked at different concentration levels in the range 1-400 ng L^-1. After sample extraction, the target analytes were simultaneously and quantitatively eluted in a single fraction of methanol, achieving enrichment factor 4000 and 1000 in river water and wastewater effluent, respectively. Full recovery for all compounds, was gained in the real matrices studied (80-125% in river water, 79-126% in wastewater effluent), with inter-day precision showing relative standard deviations (RSD) below 15% and 18% (n = 3), for river and wastewater effluent, correspondingly. The high enrichment factors coupled with high-performance liquid chromatography tandem mass spectrometry quantification (MRM mode) provided method quantification limits of 0.009-0.48 ng L^-1 in river water and 0.06-3 ng L^-1 in wastewater effluent and, at the same time, secure identification of the selected drugs. As also evidenced by comparison with literature, HA-C@silica proved to be a valid alternative to the current commercial sorbents, in terms of extraction capability, enrichment factor, ease of preparation and cost. The batch-to-batch reproducibility was assessed by recovery tests on three independently prepared HA-C@silica powders (RSD lower than 7%).

Reproductive effects of synthetic progestin norgestrel in zebrafish (Danio rerio)

The aim of this study was to assess the adverse effects of synthetic progestin norgestrel (NGT) on the reproduction of zebrafish by measuring the egg production, histology and transcriptional expression profiles along the hypothalamic-pituitary-gonadal (HPG) axis in adult zebrafish. After a pre-exposure period of 7 days, adult zebrafish were exposed to 6, 29 and 69 ng L^-1 NGT for 21 days. The results showed that exposure to 69 ng L^-1 NGT led to a significant up-regulation of follicle stimulating hormone, beta polypeptide (fshb), luteinizing hormone, beta polypeptide (lhb), progesterone receptor (pgr), estrogen receptor 1 (esr1) and androgen receptor (ar) genes in the brains, as well as significant up-regulation of hydroxysteroid 20-beta dehydrogenase (hsd20b) and hydroxysteroid 11-beta dehydrogenase 2 (hsd11b2) genes and down-regulation of 11-beta-hydroxylase (cyp11b) gene in the ovaries of females. In the testes of males, an overall down-regulation of steroidogenic acute regulatory protein (star), cytochrome P450-mediated side-chain cleavage enzyme (cyp11a1), cyp11b, hsd20b, hydroxysteroid 17-beta dehydrogenase type 3 (hsd17b3), hsd11b2 and ar genes were observed following exposure to different treatments of NGT. These transcriptional alterations imply that NGT could exhibit the potent progestogenic and androgenic activities in zebrafish. Egg production as well as histology in the ovaries and testes was not affected by NGT. Taken together, the overall results demonstrated that NGT could significantly affect transcriptional expression levels of genes related to HPG axis in zebrafish, and whether that change translates to additional physiological effects is needed further research.

Aptatope mapping of the binding site of a progesterone aptamer on the steroid ring structure

In this work we report the mapping of the binding site of the only progesterone aptamer published to date, in an approach referred to as aptatope mapping. By linking the binding data obtained from microscale thermophoresis analysis to the structural differences on the ring structure of a range of steroids, we elucidated the moieties involved in aptamer-progesterone binding. This approach can be further exploited for the characterization of aptamer specificity and ultimately facilitate the development of aptamer-based assays depending on the desired specificity.

Common deregulated gene expression profiles and morphological changes in developing zebrafish larvae exposed to environmental-relevant high to low concentrations of glucocorticoids

Synthetic glucocorticoids have been detected in environmental waters and their biological potency have raised concerns of their impact on aquatic vertebrates especially fish. In this study, developing zebrafish larvae exposed to representative glucocorticoids (dexamethasone, prednisolone and triamcinolone) at 50 pM to 50 nM from 3 h post-fertilisation to 5 days post-fertilisation were investigated. Microarray analysis identified 1255, 1531, and 2380 gene probes, which correspondingly mapped to 660, 882 and 1238 human/rodent homologs, as deregulated by dexamethasone, prednisolone and triamcinolone, respectively. A total of 248 gene probes which mapped to 159 human/rodent homologs were commonly deregulated by the three glucocorticoids. These homologs were associated with over 20 molecular functions from cell cycle to cellular metabolisms, and were involved in the development and function of connective tissue, nervous, haematological, and digestive systems. Glucocorticoid receptor signalling, NRF2-mediated oxidative stress response and RAR signalling were among the top perturbed canonical pathways. Morphological analyses using four transgenic zebrafish lines revealed that the hepatic and endothelial-vascular systems were affected by all three glucocorticoids while nervous, pancreatic and myeloid cell systems were affected by one of them. Quantitative real-time PCR detected significant change in the expression of seven genes at 50 pM of all three glucocorticoids, a concentration comparable to total glucocorticoids reported in environmental waters. Three genes (cry2b, fbxo32, and klhl38b) responded robustly to all glucocorticoid concentrations tested. The common deregulated genes with the associated biological processes and morphological changes can be used for biological inference of glucocorticoid exposure in fish for future studies.

Concentrations of select dissolved trace elements and anthropogenic organic compounds in the Mississippi River and major tributaries during the summer of 2012 and 2013

The Mississippi River drainage basin includes the Illinois, Missouri, Ohio, Tennessee, and Arkansas rivers. These rivers drain areas with different physiography, population centers, and land use, with each contributing a different suites of metals and wastewater contaminants that can affect water quality. In July 2012, we determined 18 elements (Be, Rb, Sr, Cd, Cs, Ba, Tl, Pb, Mg, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) and chlorophyll-a (Chl-a) in the five major tributaries and in the Upper Mississippi River. The following summer, we determined both trace elements and 25 trace organic compounds at 10 sites in a longitudinal study of the main stem of the Mississippi River from Grafton, Illinois to Natchez, Mississippi. We detected wastewater contaminants, including pharmaceuticals and endocrine disrupting compounds, throughout the river system, with the highest concentrations occurring near urban centers (St. Louis and Memphis). Concentrations were highest for atrazine (673 ng L^-1), DEET (540 ng L^-1), TCPP (231 ng L^-1), and caffeine (202 ng L^-1). The Illinois, Missouri, and Yazoo rivers, which drain areas with intense agriculture, had relatively high concentrations of Chl-a and atrazine. However, the Ohio River delivered higher loads of contaminants to the Mississippi River, including an estimated 177 kg day^-1 of atrazine, due to higher flow volumes. Concentrations of heavy metals (Ni, V, Co, Cu, Cd, and Zn) were relatively high in the Illinois River and low in the Ohio River, although dissolved metal concentrations were below US EPA maximum contaminant levels for surface water. Multivariate analysis demonstrated that the rivers can be distinguished based on elemental and contaminant profiles.

Progesterone potentially degrades to potent androgens in surface waters

Progesterone is a natural hormone, excreted in higher concentrations than estrogens, and has been detected in the aqueous environment. As with other compounds, it is transformed during wastewater treatment processes and in the environment. However, minor modifications to the structure may result in transformation products which still exhibit biological activity, so understanding what transformation products are formed is of importance. The current study was undertaken to identify putative transformation products resulting from spiking river water with progesterone in a laboratory-based degradation study and hence to follow the metabolic breakdown pathways. On the basis of literature reports and predictions from the EAWAG Biocatalysis/biodegradation database, target putative transformation products were initially monitored under unit resolution mass spectrometry. The identity of these transformation products was confirmed by using accurate-mass quadrupole time-of-flight. The study results highlight that transformation of progesterone can potentially create other classes of steroids, some of which may still be potent, and possess other types of biological activity.

Prednisolone impairs embryonic and posthatching development and shell formation of the freshwater snail, Physa acuta

The aim of the present study was to investigate the lethal and sublethal effects of prednisolone exposure on the embryonic and posthatching stage of the freshwater snail, Physa acuta. The egg masses were exposed for 14 d to prednisolone concentrations ranging from 15.6 μg/L to 1000 μg/L. Treatment with prednisolone at 125 μg/L to 1000 μg/L resulted in significant decline in growth, survival, and heart rate, as well as notable abnormalities in embryonic development. Premature embryonic hatching was observed at lower concentrations of 31.25 μg/L and 62.5 μg/L, whereas delayed hatching was seen at concentrations from 125 μg/L to 1000 μg/L. To assess impacts of prednisolone exposure on the hatched juveniles, the drug exposure was extended for another 28 d. Impairment of shell development was noted in juveniles exposed to concentrations from 62.5 μg/L to 1000 μg/L at the end of 42 d, which resulted in thin and fragile shells. The thickness of shells in snails exposed to 1000 μg/L was significantly lower in comparison to those in the 15.6-μg/L and control treatments. In addition, lower calcium concentration in shells of the exposed juvenile snails at treatments of 62.5 μg/L to 1000 μg/L consequently reduced their growth. The present study confirms that continuous exposure to prednisolone can result in deleterious effects on calcium deposition, resulting in shell thinning in the freshwater snail P. acuta. Environ Toxicol Chem 2016;35:2339-2348. © 2016 SETAC.

A review of the influence of treatment strategies on antibiotic resistant bacteria and antibiotic resistance genes

Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARG) in the aquatic environment have become an emerging contaminant issue, which has implications for human and ecological health. This review begins with an introduction to the occurrence of ARB and ARG in different environmental systems such as natural environments and drinking water resources. For example, ARG or ARB with resistance to ciprofloxacin, sulfamethoxazole, trimethoprim, quinolone, vancomycin, or tetracycline (e.g., tet(A), tet(B), tet(C), tet(G), tet(O), tet(M), tet(W), sul I, and sul II) have been detected in the environment. The development of resistance may be intrinsic, may be acquired through spontaneous mutations (de novo), or may occur due to horizontal gene transfer from donor bacteria, phages, or free DNA to recipient bacteria. An overview is also provided of the current knowledge regarding inactivation of ARB and ARG, and the mechanism of the effects of different disinfection processes in water and wastewater (chlorination, UV irradiation, Fenton reaction, ozonation, and photocatalytic oxidation). The effects of constructed wetlands and nanotechnology on ARB and ARG are also summarized.

Fast determination of 24 steroid hormones in river water using magnetic dispersive solid phase extraction followed by liquid chromatography-tandem mass spectrometry

The easiness-to-handle of the magnetic dispersive solid phase extraction (Mag-dSPE) procedure was developed for preconcentration of 24 steroid hormones in river water. Ethylenediamine-functionalized magnetic carbon nanotubes (EDA@Mag-CNTs) were synthesised by a simple one-pot reaction and were used as sorbent in Mag-dSPE procedure. The properties of the EDA@Mag-CNTs were characterized by transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). An ultra-fast liquid chromatography-tandem quadrupole mass spectrometry (UFLC-MS/MS) method for determination of 24 steroid hormones in river water at nanograms per liter had been developed with pretreatment of the samples by Mag-dSPE. The obtained results demonstrated the higher extraction capacity of EDA@Mag-CNT Mag-dSPE with recoveries between 82.1 and 113%. The limits of quantification (LOQs) for the steroid hormone were between 0.020 and 1.00 ng/L. The developed method had been successfully applied to 60 river water samples, and it was confirmed that EDA@Mag-CNT Mag-dSPE was a highly effective extraction method for the steroid hormone analyses.

Pharmaceuticals and personal care products in waters: occurrence, toxicity, and risk

Pharmaceuticals and personal care products (PPCP) are compounds with special physical and chemical properties that address the care of animal and human health. PPCP have been detected in surface water and wastewater in the ng/L to µg/L concentration range worldwide. PPCP ecotoxicity has been studied in a variety of organisms, and multiple methods have been used to assess the risk of PPCP in the environment to ecological health. Here we review the occurrence, effects, and risk assessment of PPCP in aquatic systems, as well as the sustainability of current methods for managing PPCP contamination in aquatic systems. The major points are the following: (1) a number of PPCP present potential concerns at environmentally relevant concentrations. PPCP mixtures may produce synergistic toxicity. (2) Various methods have been used for the ecological risk assessment of PPCP in aquatic systems. There are similarities in these methods, but no consensus has emerged regarding best practices for the ecological risk assessment of these compounds. (3) Human health risk assessments of PPCP contamination in aquatic systems have generally indicated little cause for concern. However, there is a lack of information regarding whether antibiotic contamination in wastewater and aquatic systems could lead to an increase in clinically relevant antibiotic-resistant bacteria and antibiotic-resistant genes. (4) Over the next century, the combination of increasing global population size and potential droughts may result in reduced water availability, increased need for water reuse, and increasing concentrations of PPCP in wastewaters. The current wastewater treatment methods do not remove all PPCP effectively. This, coupled with the possibility that antibiotics may promote the development of antibiotic-resistant bacteria and antibiotic-resistant genes, leads to concerns about the sustainability of global water supplies.

Effects of model aromatizable (17α-methyltestosterone) and non-aromatizable (5α-dihydrotestosterone) androgens on the adult mummichog (Fundulus heteroclitus) in a short-term reproductive endocrine bioassay

Androgens originating from pulp mill processing, sewage treatment facilities and agricultural activities have the potential for discharge into aquatic receiving environments. To assess androgen effects on reproductive endocrine status in fish in estuarine environments, male and female adult northern mummichog (Fundulus heteroclitus macrolepidotus) were exposed to an aromatizable androgen (17α-methyltestosterone; MT) and a non-aromatizable androgen (5α-dihydrotestosterone; DHT) in a short-term reproductive endocrine bioassay. Fish were nominally exposed to 10 μg/L or 100 μg/L DHT, or 0.1 μg/L or 1 μg/L MT for 14 days during gonadal recrudescence. Actual concentrations of androgens, as measured by enzyme immunoassay (EIA), were 10-49% of nominal MT 0.1, 3-6% of nominal MT 1, 5-10% of nominal DHT 10 and 3-25% of nominal DHT 100. Female mummichog were impacted to a greater degree by androgen exposure, with increased plasma testosterone (T) at 100 μg/L DHT, depressed plasma 17β-estradiol (E2) at both DHT concentrations and at 1 μg/L MT, as well as depressed in vitro E2 at both MT concentrations and 100 μg/L DHT. Males had depressed plasma T in the 10 μg/L DHT treatment and depressed in vitro 11-ketotestosterone production for both MT concentrations and 10 μg/L DHT. Ovarian aromatase gene expression was induced in females exposed to 1 μg/L MT. DHT at 100 μg/L increased hepatic vitellogenin-1 (VTG1) expression in males and depressed VTG1 expression in females. The range of responses between sexes and among species provides evidence for modes of actions and potential impacts of androgens in aquatic receiving environments.