Evidence of coprostanol estrogenicity to the freshwater mussel Elliptio complanata

Relay run property of immobilized cholesterol oxidase on magnetic biochar for sterol removal

This study investigated the biocatalytic performance of immobilized cholesterol oxidase (CHOD) on magnetite-based carbon (MBC) for degrading cholesterol. The results showed that MBC-CHOD exhibited higher activity and good affinity towards substrate compared to free enzyme and other immobilized enzymes. Mass spectra analysis revealed that MBC-CHOD damaged the main structure of cholesterol, benefitting the further biological treatment. The study proposes a Fenton process mechanism by which H2O2 is transferred to free radicals such as ·OH under acidic conditions, promoting further substrate degradation. This suggests that MBC-CHOD has a relay run property leading to high degradation of cholesterol. Molecular docking indicates that cholesterol preferentially binds to TYR-28 residue and LYS-138 residue in CHOD through hydrogen bonds. Overall, MBC-CHOD proved to be a promising candidate for efficient and sustainable cholesterol degradation.

Changes in chemical occurrence, concentration, and bioactivity in the Colorado River before and after replacement of the Moab, Utah wastewater treatment plant

Long-term (2010-19) water-quality monitoring on the Colorado River downstream from Moab Utah indicated the persistent presence of Bioactive Chemicals (BC), such as pesticides and pharmaceuticals. This stream reach near Canyonlands National Park provides critical habitat for federally endangered species. The Moab wastewater treatment plant (WWTP) outfall discharges to the Colorado River and is the nearest potential point-source to this reach. The original WWTP was replaced in 2018. In 2016-19, a study was completed to determine if the new plant reduced BC input to the Colorado River at, and downstream from, the outfall. Water samples were collected before and after the plant replacement at sites upstream and downstream from the outfall. Samples were analyzed for as many as 243 pesticides, 109 pharmaceuticals, 20 hormones, 51 wastewater indicator chemicals, 20 metals, and 8 nutrients. BC concentrations, hazard quotients (HQs), and exposure activity ratios (EARs) were used to identify and prioritize contaminants for their potential to have adverse biological effects on the health of native and endangered wildlife. There were 22 BC with HQs >1, mostly metals and hormones; and 23 BC with EARs >0.1, mostly hormones and pharmaceuticals. Most high HQs or EARs were associated with samples collected at the WWTP outfall site prior to its replacement. Discharge from the new plant had reduced concentrations of nutrients, hormones, pharmaceuticals, and other BC. For example, all 16 of the hormones detected at the WWTP outfall site had maximum concentrations in samples collected prior to the WWTP replacement. The WWTP replacement had less effect on instream concentrations of metals and pesticides, BC whose sources are less directly tied to domestic wastewater. Study results indicate that improved WWTP technology can create substantial reductions in concentrations of non-regulated BC such as pharmaceuticals, in addition to regulated contaminants such as nutrients.

Steroid-based tracing of sewage-sourced pollution of river water and wastewater treatment efficiency: Dissolved and suspended water phase distribution

In this work, the environmental distribution of steroid compounds and the level of sewage-derived contamination were assessed using sterol ratios in the confluence area of two major rivers in the Serbian capital, where raw sewage is discharged without any treatment. Special attention was paid to steroids partitioning between the dissolved and suspended phases of river and wastewater samples, since steroids tend to easily bind to particulate matter. The efficiency of sterol removal in two wastewater treatment plants in Serbia was also evaluated. Human/animal sterols coprostanol and cholesterol, and phytosterol β-sitosterol were the dominant compounds in all water samples. The sterol abundance pattern in river water was different from that in raw sewage, indicating a more pronounced biogenic input, as well as greater impact of wastewater discharges on the composition of the suspended phase. Severe contamination of the investigated area was determined, with the Danube being more contaminated than the Sava River due to different hydrodynamic conditions leading to significantly higher sterol levels in the suspended particulate matter. It was also shown that the greater part of human/animal sterols and phytosterols present in river water samples (83.0 ± 11.9 % and 87.1 ± 15.2 %) and wastewater samples (92.1 ± 6.8 % and 95.0 ± 5.7 %) was bound to suspended material compared to the dissolved phase, emphasizing the need to consider and analyze both water phases in the tracing of steroid-based environmental pollution in order to obtain a realistic picture of steroid contamination and their fate in the aquatic environment. A high removal rate (>98 %) of coprostanol and cholesterol during wastewater treatment was determined and only the coprostanol/(coprostanol + cholestanol) ratio was found to be sensitive enough to be affected by an improvement in the quality of treated wastewater.

Evaluating the potential role of bioactive chemicals on the distribution of invasive Asian carp upstream and downstream from river mile 278 in the Illinois waterway

Two non-native carp species have invaded the Illinois Waterway and are a threat to Great Lakes ecosystems. Poor water quality in the upper Illinois Waterway may be a factor contributing to the stalling of the carp population front near river mile 278. In 2015, the U.S. Geological Survey collected 4 sets of water samples from two sites upstream and 4 sites downstream from river mile 278, and one tributary. Each sample was analyzed for up to 649 unique constituents of which 287 were detected including 96 pesticides, 62 pharmaceuticals, 39 wastewater indicator chemicals, 29 metals, 19 volatile organic compounds (VOCs), 6 disinfection by-products (DBPs), 5 hormones, and 5 carboxylic acids. Potential for bioactivity was estimated by comparing chemical concentrations to aquatic life or human health criteria and to in-vitro bioactivity screening results in the U.S Environmental Protection Agency ToxCast™ database. The resulting hazard quotients and exposure-activity ratios (EARs) are toxicity indexes that can be used to rank potential bioactivity of individual chemicals and chemical mixtures. This analysis indicates that several bioactive chemicals (BCs) including: carbendazim, 2,4-D, metolachlor, terbuthylazine, and acetochlor (pesticides); 1,4-dioxane (VOC); metformin, diphenhydramine, sulfamethoxazole, tramadol, fexofenadine, and the anti-depressants (pharmaceuticals); bisphenol A, 4-nonylphenol, galaxolide, 4-tert-octylphenol (wastewater indicator chemical); lead and boron (metals); and estrone (hormone) all occur in the upper Illinois Waterway at concentrations that produce elevated EARs values and may be adversely affecting carp reproduction and health. The clear differences in water quality upstream and downstream from river mile 278 with higher contaminant concentrations and potential bioactivity upstream could represent a barrier to carp range expansion.

The synergic impacts of TiO2 nanoparticles and 17β-estradiol (E2) on the immune responses, E2 accumulation, and expression of immune-related genes of the blood clam, Tegillarca granosa

The extensive use of TiO₂ nanoparticles (nTiO₂) in industrial products has led to their release into the marine environment, thereby posing a potential risk to marine organisms. However, in addition to affecting marine organisms through its inherent properties, nTiO₂ can also act as a vehicle for other toxic pollutants due to their strong adsorption ability through the "Trojan horse" effect. Due to their potential hazard, the endocrine disrupting chemicals (EDCs) such as 17β-estradiol (E2), have been considered as one of the most serious anthropogenic threats to biodiversity and ecosystem health. However, there is still a lack of knowledge regarding the possible synergistic effects of nTiO₂ and endocrine disrupting chemicals (EDCs) on marine organisms to date. Therefore, the combined effects of nTiO₂ and 17β-estradiol (E2) on the immune responses of the blood clam, Tegillarca granosa, were investigated in this study. After 10 days of treatment, the total number, phagocytic activity, red granulocytes ratio, and the phagocytosis of hemocytes were significantly reduced in almost all treatment groups. Furthermore, expressions of genes from NFκβ and Toll-like receptor signaling pathways were significantly altered after exposure to nTiO₂ and/or E2, indicating a reduced sensitivity to pathogen challenges. In addition, compared to exposure to E2 alone, co-exposure to E2 and nTiO₂ led to a significant increase in the content of alkali-labile phosphate (ALP) in hemolymph, suggesting an enhanced E2 bioconcentration in the presence of nTiO₂. In general, the present study demonstrated that nTiO₂ enhanced the immunotoxicity of E2 to the blood clam, which may be due to the increased E2 uptake in the presence of nTiO₂.

Assessment of ecosystem health disturbance in mangrove-lined Caribbean coastal systems using the oyster Crassostrea rhizophorae as sentinel species

This investigation was aimed at contributing to develop a suitable multi-biomarker approach for pollution monitoring in mangrove-lined Caribbean coastal systems using as sentinel species, the mangrove cupped oyster, Crassostrea rhizophorae. A pilot field study was carried out in 8 localities (3 in Nicaragua; 5 in Colombia), characterized by different environmental conditions and subjected to different levels and types of pollution. Samples were collected in the rainy and dry seasons of 2012-2013. The biological effects at different levels of biological complexity (Stress-on-Stress response, reproduction, condition index, tissue-level biomarkers and histopathology) were determined as indicators of health disturbance, integrated as IBR/n index, and compared with tissue burdens of contaminants in order to achieve an integrative biomonitoring approach. Though modulated by natural variables and confounding factors, different indicators of oyster health, alone and in combination, were related to the presence of different profiles and levels of contaminants present at low-to-moderate levels. Different mixtures of persistent (As, Cd, PAHs) and emerging chemical pollutants (musk fragrances), in combination with different levels of organic and particulate matter resulting from seasonal oceanographic variability and sewage discharges, and environmental factors (salinity, temperature) elicited a different degree of disturbance in ecosystem health condition, as reflected in sentinel C. rhizophorae. As a result, IBR/n was correlated with pollution indices, even though the levels of biological indicators of health disturbance and pollutants were low-to-moderate, and seasonality and the incidence of confounding factors were remarkable. Our study supports the use of simple methodological approaches to diagnose anomalies in the health status of oysters from different localities and to identify potential causing agents and reflect disturbances in ecosystem health. Consequently, the easy methodological approach used herein is useful for the assessment of health disturbance in a variety of mangrove-lined Caribbean coastal systems using mangrove cupped oysters as sentinel species.

Sterol ratios as a tool for sewage pollution assessment of river sediments in Serbia

In this work, source pollution tracing of the sediments of the Danube River and its tributaries in Serbia was performed using sterol ratios. Improved liquid chromatography-tandem mass spectrometry method, which enabled complete chromatographic separation of four analytes with identical fragmentation reactions (epicoprostanol, coprostanol, epicholestanol and cholestanol), was applied for the determination of steroid compounds (hormones, human/animal and plant sterols). A widespread occurrence of sterols was identified in all analyzed samples, whereas the only detected hormones were mestranol and 17α-estradiol. A human-sourced sewage marker coprostanol was detected at the highest concentration (up to 1939 ng g(-1)). The ratios between the key sterol biomarkers, as well as the percentage of coprostanol relative to the total sterol amount, were applied with the aim of selecting the most reliable for distinction between human-sourced pollution and the sterols originated from the natural sources in river sediments. The coprostanol/(cholesterol + cholestanol) and coprostanol/epicoprostanol ratios do not distinguish between human and natural sources of sterols in the river sediments in Serbia. The most reliable sterol ratios for the sewage pollution assessment of river sediments in the studied area were found to be coprostanol/(coprostanol + cholestanol), coprostanol/cholesterol and epicoprostanol/coprostanol. For the majority of sediments, human-derived pollution was determined. Two sediment samples were identified as influenced by a combination of human and natural biogenic sources.

Are fecal stanols suitable to record and identify a pulse of human fecal contamination in short-term exposed shellfish? A microcosm study

In this study, the capacity of oysters to bioaccumulate fecal stanols and to record a source-specific fingerprint was investigated by the short-term contamination of seawater microcosms containing oysters with a human effluent. Contaminated oysters bioaccumulated the typical fecal stanols coprostanol and 24-ethylcoprostanol and their bioaccumulation kinetics were similar to that of the Fecal Indicator Bacteria Escherichia coli used in European legislation. Although stanol fingerprints of contaminated water allowed the identification of the human specific fingerprint, this was not the case for oysters. This discrepancy is attributed to (i) high concentrations of endogenous cholestanol and sitostanol, responsible for "unbalanced" stanol fingerprints, (ii) different accumulation/depuration kinetics of fecal coprostanol and 24-ethylcoprostanol and (iii) the limits of the analytical pathway used. These results show that fecal stanols bioaccumulated by oysters are useful to record fecal contamination but the usefulness of stanol fingerprints to identify specific sources of contamination in shellfish currently seems limited.

Evaluation of yolk protein levels as estrogenic biomarker in bivalves; comparison of the alkali-labile phosphate method (ALP) and a species-specific immunoassay (ELISA)

Altered concentration of the vertebrate yolk protein precursor vitellogenin is a recognized biomarker for endocrine disruption in fish, and within recent years yolk protein alteration has also been associated with endocrine disruption in bivalves. Species-specific, direct and sensitive methods for quantification of vitellogenin in fish have been available for years whereas bivalve yolk protein levels have been estimated indirectly by alkali-labile phosphate (ALP) liberated from high molecular weight proteins because the sequence and biochemical structure of most bivalve yolk proteins are unknown. By applying a species-specific enzyme-linked immunosorbent assay (ELISA) for accurate determination of yolk protein level the impact of 17β-estradiol (57, 164 and 512 ng/L) on the freshwater bivalve Unio tumidus was investigated and compared with ALP estimations. Seven weeks of exposure during the pre-spawning and spawning period had no consistent effect on yolk protein concentration in hemolymph, and ALP levels in hemolymph also remained unchanged in both males and females. Further, basal male and female ALP levels were indistinguishable whereas the ELISA demonstrated that yolk protein levels of females exceeded male levels at the time of sampling, although male basal levels were high compared to fish. Altogether it is shown that individual ALP levels do not reflect yolk protein levels and hence hemolymph ALP levels cannot serve as biomarker for estrogenic exposure during the pre-spawning and spawning period in U. tumidus. The necessity of sensitive and validated biomarkers for reliable interpretation of data and the utility of ALP and yolk protein levels as biomarkers in bivalves are discussed.

Hormones, sterols, and fecal indicator bacteria in groundwater, soil, and subsurface drainage following a high single application of municipal biosolids to a field

A land application of dewatered municipal biosolids (DMB) was conducted on an agricultural field in fall 2008 at a rate of 22Mg dry weight (dw) ha(-1). Pre- and post- application, hormone, sterol and fecal indicator bacteria concentrations were measured in tile drainage water, groundwater (2, 4, 6m depth), surface soil cores, and DMB aggregates incorporated in the soil (∼0.2m depth) for a period of roughly 1year post-application. Hormones and sterols were detected up to 1year post-application in soil and in DMB aggregates. Hormone (androsterone, desogestrel, estrone) contamination was detected briefly in tile water samples (22d and ∼2months post-app), at lowngL(-1) concentrations (2-34ngL(-1)). Hormones were not detected in groundwater. Sterols were detected in tile water throughout the study period post-application, and multiple fecal sterol ratios suggested biosolids as the source. Coprostanol concentrations in tile water peaked at >1000ngL(-1) (22d post-app) and were still >100ngL(-1) at 6months post-application. Fecal indicator bacteria were detected throughout the study period in tile water, groundwater (⩽2m depth), soil and DMB aggregate samples. These bacteria were strongly linearly related to coprostanol in tile water (R(2)>0.92, p<0.05). The limited transport of hormones and sterols to tile drainage networks may be attributed to a combination of the hydrophobicity of these compounds and limited macroporosity of the field soil. This transitory contamination from hormones and sterols is unlikely to result in any significant pulse exposure risk in subsurface drainage and groundwater.

Do mollusks use vertebrate sex steroids as reproductive hormones? II. Critical review of the evidence that steroids have biological effects

In assessing the evidence as to whether vertebrate sex steroids (e.g. testosterone, estradiol, progesterone) have hormonal actions in mollusks, ca. 85% of research papers report at least one biological effect; and 18 out of 21 review papers (published between 1970 and 2012) express a positive view. However, just under half of the research studies can be rejected on the grounds that they did not actually test steroids, but compounds or mixtures that were only presumed to behave as steroids (or modulators of steroids) on the basis of their effects in vertebrates (e.g. Bisphenol-A, nonylphenol and sewage treatment effluents). Of the remaining 55 papers, some can be criticized for having no statistical analysis; some for using only a single dose of steroid; others for having irregular dose-response curves; 40 out of the 55 for not replicating the treatments; and 50 out of 55 for having no within-study repetition. Furthermore, most studies had very low effect sizes in comparison to fish-based bioassays for steroids (i.e. they had a very weak 'signal-to-noise' ratio). When these facts are combined with the fact that none of the studies were conducted with rigorous randomization or 'blinding' procedures (implying the possibility of 'operator bias') one must conclude that there is no indisputable bioassay evidence that vertebrate sex steroids have endocrinological or reproductive roles in mollusks. The only observation that has been independently validated is the ability of estradiol to trigger rapid (1-5 min) lysosomal membrane breakdown in hemocytes of Mytilus spp. This is a typical 'inflammatory' response, however, and is not proof that estradiol is a hormone - especially when taken in conjunction with the evidence (discussed in a previous review) that mollusks have neither the enzymes necessary to synthesize vertebrate steroids nor nuclear receptors with which to respond to them.

Immunotoxicity of surface waters contaminated by municipal effluents to the snail Lymnaea stagnalis

The immunotoxic effects of surface waters contaminated by a municipal effluent dispersion plume were examined in the snail Lymnaea stagnalis. Snails were exposed to surface waters where changes in hemocyte counts, viability, levels of reactive oxygen species (ROS), reduced thiols and phagocytic activity were tracked following exposure periods of 3h and 3 and 7d. Changes in mRNA expression of some genes in the hemocytes were also assessed after 7d of exposure, as follows: genes coding for catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GSR), selenium-dependent glutathione peroxidase (SeGPX), two isoforms of the nitric oxide synthetase (NOS1 and NOS2), molluscan defensive molecule (MDM), toll-like receptor 4 (TLR4), allograft inflammatory factor-1 (AIF), and heat-shock protein 70 (HSP70). At the sites closest to the discharge point, exposure led to impaired hemocyte viability and intracellular thiol levels and also an increase of hemocyte count, ROS levels and phagocytosis. Phagocytosis and ROS levels in hemocytes were correlated with heterotrophic bacterial counts in snails. We found four genes with increased mRNA expression as a response to exposure of municipal wastewaters: TLR4 (6-fold), HSP70 (2-fold), SeGPx (4-fold) and CAT (2-fold). Immunocompetence responses were analyzed by canonical analysis to seek out relationships with mRNA expression of the genes involved in stress, pattern recognition, cellular and humoral responses. The data revealed that genes involved in oxidative stress were strongly involved with immunocompetence and that the resulting immune responses were influenced both by the bacterial and pollutant loadings of the effluent.

A state-wide survey in Oregon (USA) of trace metals and organic chemicals in municipal effluent

Oregon's Senate Bill 737, enacted in 2007, required the state's 52 largest municipal wastewater treatment plants (WWTP) and water pollution control facilities (WPCF) to collect effluent samples in 2010 and analyze them for persistent organic pollutants. These facilities are located state-wide and represent a variety of treatment types, service population sizes, geographic areas, and flow conditions. Of the 406 chemicals ultimately analyzed, 114 were detected above the level of quantification (LOQ) in at least one sample. Few persistent pollutants were found possibly because of their diversion from effluent via sorption to sludge (solids phase) or high LOQs for certain chemicals. Several pesticides, as well as benzene and phenol degradation products, all previously unreported in effluent, were detected. Ten polychlorinated biphenyls (PCB) congeners were present at low concentrations in ≤ 10 samples, while polychlorinated naphthalenes and dioxins/furans were not detected at all. Twenty-one polybrominated diphenyl ether (PBDE) congeners were found, nine of which have been reported in Osprey eggs in Oregon and Washington. Methylmercury was present in 65% of samples, with average and maximum concentrations of 0.18 and 1.36 ng/L, respectively. Although they are generally assumed to be innocuous by-products of sewage treatment, additional research is needed on potential impacts to aquatic ecosystems of high loadings of coprostanol and cholesterol. These results suggest that effluent, rather than just receiving waters, should itself be analyzed for a wide range of contaminants in order to understand how upstream sources, conveyed through WWTPs and WPCFs, could be impacting aquatic ecosystems.

Acute toxicity of nonylphenols and bisphenol A to the embryonic development of the abalone Haliotis diversicolor supertexta

Acute toxic effects and mechanisms of two typical endocrine disrupting chemicals, nonylphenols (NPs) and bisphenol A (BPA), to the embryonic development of the abalone Haliotis diversicolor supertexta, were investigated by the two-stage embryo toxicity test. The 12-h median effective concentrations (EC(50)) of NPs and BPA to the trochophore development were 1016.22 and 30.72 μg L(-1), respectively, and the respective 96-h EC(50) values based on the completion of metamorphosis (another experimental endpoint) were reduced to 11.65 and 1.02 μg L(-1). Longer exposure time and magnified exposure concentrations in the benthic diatom, that serves as both food source and settlement substrate during the metamorphosis, via bioaccumulation, led to the higher sensitivity of metamorphosis to target EDCs compared with the trochophore development. The hazard concentrations for 5% of the species (HC(5)) could be employed as the safety thresholds for the embryonic development of the abalone. The 12-h HC(5) values of NPs and BPA were 318.68 and 13.93 μg L(-1), respectively, and the respective 96-h HC(5) values were 0.99 and 0.18 μg L(-1), which were at environmentally relevant levels. Results of proteomic responses revealed that NPs and BPA altered various functional proteins in the abalone larvae with slight differences between each chemical and affected various physiological functions, such as energy and substance metabolism, cell signalling, formation of cytoskeleton and cilium, immune and stress responses at the same time, leading to the failure of metamorphosis.

Presence of natural and anthropogenic organic contaminants and potential fish health impacts along two river gradients in Alberta, Canada

In the current study, 28 organic contaminants were measured, many with estrogen-like activity, in water collected from 16 sites on two rivers in the South Saskatchewan River Basin, Alberta, Canada. The compounds detected included synthetic estrogens (birth control pill compounds and hormone therapy drugs) downstream of municipal wastewater effluents and natural hormones downstream of municipal wastewater effluents and in agricultural areas. Greater concentrations of cholesterol and derivatives, phytosterols, and fecal sterols were measured at the most downstream sites, which indicates cumulative inputs of such compounds in these rivers. A native minnow (longnose dace, Rhinichthys cataractae) was sampled to assess pathophysiological responses to exposure to compounds with estrogen-like activity. Hepatic vitellogenin protein was detected in at least one adult male longnose dace from 14 of 15 sites sampled for fish. Vitellogenin was negatively correlated with hepatosomatic (r = -0.47, p < 0.001) and gonadosomatic (r = -0.44, p < 0.003) indices, which suggests potential health impacts in male longnose dace in the South Saskatchewan River Basin. The current study demonstrates that organic contaminants, many with estrogen-like activity, are distributed over hundreds of kilometers throughout the South Saskatchewan River Basin and not just downstream of major point-sources. Therefore, many activities within these basins impact water quality in the South Saskatchewan River Basin and affect endemic longnose dace populations.

Environmental levels of atrazine decrease spatial aggregation in the freshwater mussel, Elliptio complanata

The commonly used herbicide atrazine (ATR), may cause estrogen-like alterations and, like other xenoestrogens, may alter behavior. Here effects on animal aggregation were tested in freshwater mussels exposed short-term to ecologically relevant ATR concentrations between 1.5 and 150microg/L. The aggregation index (AI), the fraction of mussels in the most densely populated tank section, was evaluated and showed higher AI at later times in both 6- and 72-h trials (p<0.001). After 72h, there was also less aggregation in estradiol- and mid-ATR-treated animals, 26% and 24% less than control, respectively (p<0.04). These data suggest that freshwater mussels tend to aggregate, that 72-h exposure to ecologically relevant ATR concentrations decreases aggregation, and that estradiol exposure has a similar effect. Given that bivalve aggregation may be related to reproduction, the results suggest that low concentrations of ATR may have ecological consequences on animal populations in this species.

Vitellogenin as a biomarker of exposure to estrogenic compounds in aquatic invertebrates: a review

Vitellogenins (Vg) are the major precursor of the egg-yolk proteins, vitellins (Vn), which provide energy reserves for embryonic development in oviparous organisms. In mature females, Vg are generally synthesised in response to endogenous estrogens, such as 17beta-estradiol (E2), released into the bloodstream and then stored in developing oocytes. In males, the Vg gene, although present, is normally silent. However, it may be activated by (xeno)-estrogens. These substances belong to a large and heterogeneous group of environmental contaminants capable of altering endocrine functions in organisms. For this reason, they are named endocrine disrupting chemicals (EDCs). Natural steroidal estrogens [E2, estrone (E1), estriol (E3)] and synthetic chemicals, such as pesticides, polychlorinated biphenyls (PCBs) and household products (surfactants) are estrogenic compounds widespread in aquatic ecosystems. The main sources of contamination mostly stem (or originate) from municipal and industrial effluents, agricultural practices, livestock wastes and sewage treatment plants (STP). Recently, Vg induction, mainly in males and immature females, has been proposed as a useful biomarker to assess estrogenic contamination in aquatic environments. Indeed, estrogenicity of individual chemicals and mixtures has extensively been evaluated, in both laboratory and field studies, albeit mostly in fish. In contrast, limited attention has centred on evaluating xenoestrogen effects in aquatic invertebrates, probably owing to limited knowledge of their endocrinology. This review focuses on a brief description of xenoestrogens and their occurrence in aquatic environments, and on Vg induction in aquatic invertebrates in response to both experimental and environmental exposure to estrogenic compounds. Results of recent field and laboratory studies are presented. In addition, new perspectives about the use of Vg induction as a biomarker of exposure to estrogenic compounds are also discussed.

Endocrine-related reproductive effects in molluscs

Research on endocrine disruption has been a major topic of the past decade. Although most studies concentrated on vertebrate species, invertebrates are now gaining more attention. In particular, data on molluscs is increasing. One of the best-documented and more relevant examples of endocrine disruption is the imposex phenomenon affecting some gastropod species. But the increasing interest is also due to the fact that molluscs, especially bivalves, are good bioindicators used for decades in environmental studies and that progress have been made in the understanding of the physiology and endocrinology of some mollusc species. Recent results suggest that molluscs can be adversely affected by compounds that alter their reproduction and that vertebrate-type sex-steroids metabolism or mechanism of action could be involved in these effects. Nevertheless, the endocrine system of molluscs appears to be dissimilar in many aspects to those of vertebrates and sex-steroids might not have the same importance in all mollusc species. This diversity constitutes an important opportunity to examine and understand new and alternative mechanisms for endocrine disruption.

Body burden of contaminants and biological effects in mussels: an integrated approach

An investigation of contaminants and biological effects in mussels from Halifax Harbour, Nova Scotia, Canada, focused on a 6 km section in the central most industrialized core of the harbour, where a site was previously identified as highly contaminated. The aim of the study was to compare the body burden of mussels in terms of polycyclic aromatic hydrocarbons (PAH), dichlorophenyltrichloroethane (DDT family), coprostanol and elements, relative to biological parameters such as condition indices, sex ratio, survival time in air, and to biochemical indicators of mussels' health analysed in gills, digestive gland and gonad tissues. These markers are total sugar and lipid content of gonads, mitochondrial electron transport activity in digestive gland and gonad tissues, lipid peroxidation in gill, digestive gland and gonad tissues, and heme oxidase activity in the digestive gland. At the north western end of the area, near a major sewage effluent, shorter survival time, higher oxidative stress and metabolism, gonad electron transport activity, levels of coporostanol, PAH, p,p'-dichlorophenyldichlo-roethylene (p,p'-DDE), Ag, Cu, Fe and P were observed. At the opposite south eastern end, longer survival time, higher lipid content, lowest condition indices and concentrations of coprostanol, PAH and p,p'-DDE, but higher concentrations of Sn and Cd, were detected. On-going improvements to sewage treatment in Halifax Harbour, including construction of sewage treatment plants that will discharge into deeper parts of the central harbour, should improve inter-tidal mussels' health in our study area.

First evidence of altered vitellogenin-like protein levels in clam Tapes philippinarum and in cockle Cerastoderma glaucum from the Lagoon of Venice

Possible xenoestrogenic effects were investigated, for the first time, in two bivalve species from the Lagoon of Venice (Italy): the clam Tapes philippinarum and the cockle Cerastoderma glaucum. Bivalves were collected far from their reproductive phase at the very early stage of gametogenesis (January), and in the pre-spawning period (June) in six sites. Vitellogenin (Vg)-like proteins (a biomarker of exposure to estrogenic compounds) were measured by the alkali-labile phosphate method (ALP), in both haemolymph and digestive gland from males and females (when it was possible to distinguish sex by microscopic observation of gonadal tissue). Haemolymph calcium concentrations (a parameter considered closely related to the presence of Vg-like proteins) and the bivalve condition index (CI) were also measured. In both seasons, bivalves collected at Campalto (near a sewage treatment plant) and Marghera (a highly contaminated area) had higher Vg-like protein levels, particularly in haemolymph, than animals from the other sampling sites. Interestingly, CI had high values in these polluted sites. In June only, Vg-like proteins and Ca(2+) levels in haemolymph exhibited similar trends in both bivalve species at most sampling sites. The responsiveness of bivalves to environmental xenoestrogens was higher in June, allowing better discrimination among sites. The present study demonstrates that animals from highly polluted areas have increased Vg-like protein levels. As endocrine disruption due to exposure to estrogenic compounds may cause fertility reduction, alterations in the sex ratio, and a decrease in reproductive rate, a condition of potential risk for bivalve populations in estuarine areas is highlighted.

An assessment of estrogenic organic contaminants in Canadian wastewaters

A suite of 30 primarily estrogenic organic wastewater contaminants was measured in several influent/effluent wastewater samples from four municipal wastewater treatment plants and effluents from one bleached kraft pulp mill (BKME) using an ultra-trace analytical method based on gas chromatography-high resolution mass spectroscopy (GC-HRMS). In vitro recombinant yeast assay detection of the estrogenic equivalent (EEq) on whole and solid phase extracted (SPE) and fractionated wastewater was also performed. 19-norethindrone was the most frequently detected and abundant (26-224 ng/L) of all the synthetic estrogens/progesterones in the influent samples. 17alpha-ethinylestradiol was the more frequently detected synthetic estrogen/progesterone in the effluents occurring at or below 5 ng/L with some sporadic occurrences of up to 178 ng/L. The greatest levels of steroidal estrogens in municipal effluents were E1>E2>E3 which were all <20 ng/L. Nonylphenol and di(2-ethylhexyl) phthalate were found to be the highest non-steroidal synthetic compounds surveyed in both municipal influent and effluent samples, both occurring at 6-7 microg/L in municipal effluents. BKME contained relatively large amounts of the plant sterol stigmasterol (4 microg/L) but low amounts of fecal sterols, and steroidal estrogens (E2 only at 6 ng/L) when compared to the municipal effluents. In vitro EEq in the wastewater surveyed ranged from 9-106 ng E2/L and ranked from municipal influent>municipal effluent approximately BKME, with most of the estrogenicity fractionating in the 100% methanol SPE fraction followed by a secondary amount in the diethyl ether (for municipal) or methyl-tert butyl ether (for BKME) SPE fractions. Most correlations between chemical and in vitro estrogenic equivalency were weak (p>0.05 in most cases). Unexpected inverse correlations between in vitro estrogenic activity and concentrations of the estrogenic contaminant bisphenol A were found which likely contributed to the weakness of these correlations. A modified toxicity identification and evaluation procedure was continued with the SPE extracts from the more potent 100% methanol SPE fractions of municipal effluent. High performance liquid chromatography band elution retention times, based on in vitro estrogen detection, indicated that steroidal estrogens such as E2 were responsible for most of the estrogenicity of the samples. Subsequent collection and GC-MS analysis of active bands did not confirm the presence of steroidal estrogens, but expanded the possibility of phthalate esters (i.e. dibutyl phthalate) and natural sterols (i.e. beta-sitosterol) contributing to the overall estrogenic load.

Determination of sterols, estrogens and inorganic ions in waste water and size-segregated aerosol particles emitted from waste water treatment

Concentrations of steroids and inorganic ions were measured in waste water of an aerated sand trap as well as in aerosol particles emitted from this tank at the waste water treatment plant (WWTP) of Bayreuth, Germany, in January and February 2003. The investigations comprised seven sterols, two estrogens, and several inorganic ions. Since an appropriate method for the determination of sterols in waste water was not available, a new method based on solid phase extraction was developed. The concentrations of the sterols coprostanol and cholesterol amounted to 30-180 microg l(-1) in waste water and to 400-5000 pg m(-3) in aerosol particles. All other sterols were present in markedly lower concentrations. The mean concentrations of the two estrogens estrone and 17beta-estradiol were about 165 pg m(-3) in aerosol particles. The steroid concentrations in both waste water and aerosol particles varied greatly over time, however with the exception of coprostanol, no clear correlation was detected between concentrations in waste water and aerosol particles.

Endocrine disruptors in marine organisms: approaches and perspectives

Organic pollutants exhibiting endocrine disrupting activity (Endocrine Disruptors--EDs) are prevalent over a wide range in the aquatic ecosystems; most EDs are resistant to environmental degradation and are considered ubiquitous contaminants. The actual potency of EDs is low compared to that of natural hormones, but environmental concentrations may still be sufficiently high to produce detrimental biological effects. Most information on the biological effects and mechanisms of action of EDs has been focused on vertebrates. Here we summarize recent progress in studies on selected aspects of endocrine disruption in marine organisms that are still poorly understood and that certainly deserve further research in the near future. This review, divided in four sections, focuses mainly on invertebrates (effects of EDs and mechanisms of action) and presents data on top predators (large pelagic fish and cetaceans), a group of vertebrates that are particularly at risk due to their position in the food chain. The first section deals with basic pathways of steroid biosynthesis and metabolism as a target for endocrine disruption in invertebrates. In the second section, data on the effects and alternative mechanisms of action of estrogenic compounds in mussel immunocytes are presented, addressing to the importance of investigating full range responses to estrogenic chemicals in ecologically relevant invertebrate species. In the third section we review the potential use of vitellogenin (Vtg)-like proteins as a biomarker of endocrine disruption in marine bivalve molluscs, used worldwide as sentinels in marine biomonitoring programmes. Finally, we summarize the results of a recent survey on ED accumulation and effects on marine fish and mammals, utilizing both classical biomarkers of endocrine disruption in vertebrates and non-lethal techniques, such as non-destructive biomarkers, indicating the toxicological risk for top predator species in the Mediterranean. Overall, the reviewed data underline the potential to identify specific types of responses to specific groups of chemicals such as EDs in order to develop suitable biomarkers that could be useful as diagnostic tools for endocrine disruption in marine invertebrates and vertebrates.

Biomarkers of exposure and reproduction-related effects in mussels exposed to endocrine disruptors

Biomarkers are useful tools to study the health of estuarine and marine ecosystems. Biomarkers can be measured in different organisms, but mussels have acquired a global importance as sentinels in marine pollution-monitoring programs. In the present work, we aimed to determine the effects of different endocrine disruptors in mussels by using peroxisome proliferation as a biomarker of exposure to organic pollutants and the levels of vitellogenin (Vtg)-like proteins as biomarker of endocrine disruption. In experiment 1, mussels Mytilus edulis were exposed for 3 weeks to North Sea crude oil (NSO 0.5 ppm) and a mixture of 0.5 ppm NSO, 0.1 ppm alkylphenol mix, and 0.1 ppm extra polycyclic aromatic hydrocarbons (PAHs) (MIX). In experiment 2, mussels were exposed for 3 weeks to diallylphthalate (DAP 50 ppb), bisphenol-A (BPA 50 ppb), and tetrabromodiphenylether (TBDE 5 ppb). Peroxisome proliferation was assessed by measuring acyl-CoA oxidase (AOX) activity and peroxisomal volume density (VVp) in digestive gland. Vtg-like protein levels were measured in gonads by the alkali-labile phosphate (ALP) method. Gonad was also analyzed histologically, and the gonad index (GI) calculated. Mussels exposed to NSO and MIX showed significantly increased AOX activities and VVP compared with control animals. Significantly higher VVP was also found in DAP- and TBDE-exposed mussels. Effects on ALP and GI depended significantly on sex and time of year. In female mussels, ALP levels and GI were lower in the NSO group. In male mussels, ALP levels were significantly increased in the MIX group. The volume density of athretic oocytes was higher in the NSO and MIX exposure groups than in controls, and gonad resorption was observed in the BPA exposure group. Our results confirm the usefulness of peroxisome proliferation as a biomarker of exposure to organic contaminants in mussels and indicate that changes in Vtg-like proteins could be used as potential indicator of pollutant effects on mussel reproduction.

Evaluation of the lethal and sub-lethal toxicity and potential endocrine disrupting effect of nonylphenol on the zebra mussel (Dreissena polymorpha)

Nonylphenol (NP) is commonly found in surface waters nearby municipal wastewater treatment plants and was shown to have endocrine disrupting effects in aquatic organisms. The purpose of this study was to investigate the toxicity and potential endocrine disrupting effects of NP on the freshwater zebra mussel (Dreissena polymorpha). Toxicity assessment yielded LC(50) values of 3.68, 2.19 and 1.62 mg L(-1) after 15, 35 and 50 days of exposure, respectively. LC(10) values of 1.6, 1.11 and 0.68 mg L(-1) were respectively obtained for similar exposure periods. At concentrations >5 mg L(-1), mortality effects were significant, as were those relating to attachment and siphon extension (indicating filtration), both general indicators of health. Endocrine disruption effects were investigated after a prolonged exposure (112 d) to 5 and 500 microg L(-1) NP by measuring Vitellin (Vn)-like protein levels using the alkali-labile phosphate (ALP) assay and gel electrophoresis (GE). An increase in ALP levels was observed in both male and female mussels, although only marginal owing to a significant decrease in the mussels' health indicated by its condition, during the experiment. These levels, however, increased proportionally with NP concentration. Using solid phase thin-layer chromatography, we confirmed increased levels of the steroid cholesterol and evidence of NP uptake. Cholesterol levels in gonad tissue proved to be a more responsive biomarker of exposure to NP than levels of ALP. Further implications relating to the occurrence of endocrine disruption in the zebra mussel are discussed.

Can 4-nonylphenol induce vitellogenin-like proteins in the clam Tapes philippinarum?

Vitellogenins (Vg) are precursors of egg-yolk proteins (vitellins) constituting energy reserves for embryos. In oviparous females, Vg are produced in the liver (or equivalent organs) under the control of endogenous estrogens, released into the bloodstream (plasma or hemolymph), and stored in developing oocytes. Although Vg levels are generally undetectable in male plasma, they may significantly increase in (xeno-)estrogen-exposed males. The aim of the present study was to evaluate estrogenic effects of 4-nonylphenol (NP) in sexually differentiated males and females of the Manila clam Tapes philippinarum. Clams were exposed for 7 days to various sublethal NP concentrations (0, 0+acetone, 0.025, 0.05, 0.1, and 0.2 mg NP/L) and Vg-like protein levels were evaluated in both hemolymph and digestive glands of mollusks by the alkali-labile phosphate assay. This method, based on the determination of phosphates released by Vg, has previously been used to detect Vg concentrations in both fish plasma and bivalve hemolymph. Although Vg levels were generally higher in both hemolymph and digestive gland of T. philippinarum females, males appeared to be more sensitive than females to the estrogenic effects of NP. In males exposed to 0.1 and 0.2 mg NP/L, Vg levels increased significantly in both hemolymph (P < 0.05 and P < 0.01, respectively) and digestive gland (p < 0.05), whereas no changes were observed in those of females. Although the mechanisms by which NP exerts its in vivo endocrine-modulating effects in bivalve mollusks remain unclear, the results of this study demonstrate that NP may induce Vg-like proteins in T. philippinarum, particularly males.

The endocrine disrupting effect of municipal effluent on the zebra mussel (Dreissena polymorpha)

Municipal effluents have been shown to contain a cocktail of endocrine disrupting chemicals (EDCs). The estrogenic effect of these effluents has been demonstrated on both vertebrate and invertebrate species by the feminisation of the exposed males. This effect was investigated on the freshwater zebra mussel (Dreissena polymorpha) after exposure to tertiary treated effluent from a municipal sewage treatment works (STW). Mussels were exposed to the effluent in situ for 112 days during gametogenesis (December to mid-March). Levels of vitellin (Vn)-like proteins (the major protein found in oocytes) were measured indirectly using the alkali-labile phosphate (ALP) technique and confirmed by gel electrophoresis. Significant increases (P < 0.05) in Vn-like proteins were found in both male and female mussels after exposure to the effluent, indicating that endocrine disruption (ED) had occurred. Using High-performance thin layer chromatography (HPTLC) levels of the mussels main steroid, cholesterol were found to more than double after effluent exposure. General physiological (survival, condition, etc.) and histological effects were also investigated. Histological effects observed included a large increase in interstitial tissue between the seminiferous tubules of the gonad in male mussels exposed to effluent. Effluent samples were tested for estrogenic compounds using the toxicity identification and evaluation method (TIE). A complex mixture of compounds with estrogenic activity was found with 17beta-estradiol, 17alpha-ethynlestradiol and bisphenol A accounting for the majority of the effluents estrogenic activity. Results indicate that the zebra mussel is a suitable bioindicator of endocrine disruption in freshwater environments.

Estrogenicity of solid phase-extracted water samples from two municipal sewage treatment plant effluents and river Rhine water using the yeast estrogen screen

In the present study, the yeast estrogen screen (YES) was used to estimate the estrogenic potential of solid phase-extracted water samples from the effluents of two municipal sewage treatment plants (STPs 1 + 2) and from four lanes (left to right) of the river Rhine at Worms, Germany, i.e. downstream the STPs. Estrogenic activities of extracted water samples were expressed as 17beta-estradiol equivalents (E(2)-EQs). Estrogenic activity was detected in the effluents of both STPs with values of 0.242 +/- 0.038 nM (65.96 +/- 10.4 ng/l) and 0.125 +/- 0.026 nM E(2)-EQs (34.1 +/- 7.18 ng/l) at STP 1 and 2, respectively. In river Rhine water, estrogenic activity was lower, however, displaying significant differences between the left and right bank of the river (0.044 +/- 0.003 nM E(2)-EQs [11.97 +/- 0.7 ng/l] for lanes 1-3; 0.071 +/- 0.01 nM E(2)-EQs [19.42 +/- 2.8 ng/l] for lane 4). Chemical analysis of corresponding water samples resulted in a potential estrogenic response in the YES, expressed as E(2)-EQs for the known estrogens and phytoestrogens in the STP effluents with values up to 0.0662 nM E(2)-EQs (18.04 ng/l). In Rhine water from lane 4, however, total estrogenic activity of steroidal estrogens was equal to 0.014 nM E(2)-EQs (3.8 ng/l). Furthermore, total concentrations of flavonoids, fecal- and phytosteroids and resorcyclic lactones were about 1.2 microg/l at STP 1, 0.62 microg/l at STP 2 and 0.25 microg/l at the river Rhine, lane 4. Results indicate that estrogenic activity can clearly be measured in SPT effluents as well as in river Rhine water using the YES in combination with chemical analysis. Results from the bioassay, however, indicated a higher estrogenic potential (expressed as E(2)-EQs) than that obtained by chemical analysis.

Determination of endocrine-disrupting compounds in environmental samples using gas and liquid chromatography with mass spectrometry

This paper describes certain applications for endocrine-disrupting compounds determination. LC-MS was applied using an electrospray ionization (ESI) technique in positive mode for alcohol polyethoxylates and nonylphenol and octylphenol polyethoxylates (NPEOn and OPEOn), and in negative mode for 4-nonylphenol (4-NP) and 4-octylphenol (4-OP) to determine targeted compounds in wastewater and sludge. GC-MS and GC-MS-MS were used to determine 4-NP, 4-tert.-octylphenol (4-t-OP), bisphenol A, estradiol-17beta, estriol estrone, testosterone, 17alpha-ethynylestradioL cholesterol, coprostan-3-ol, coprostan and coprostan-3-one in both surface water and wastewater after derivatization with N,O-bis(trimethyl-silyl)trifluoroacetamide (BSTFA). Extraction from the water samples was by an SPE technique, using either a copolymeric (Oasis HLB) or C18 silica sorbents, depending on the target contaminants. Extraction from the sludge samples was by a Soxtec system using methanol. Percentage recoveries for most of the selected compounds, using either a copolymeric (Oasis HLB) or C18 silica sorbents, were satisfactory (>60%). Quantification limits for the target compounds were at ppb levels in both water and sludge samples when using LC-ESI-MS in both positive and negative modes. They reached ppt levels in water when using GC-MS (in large volume injection mode) and GC-MS-MS. The results revealed 4-NP, NPEOn and AEOs in sludge samples at a concentration range of 1.3-8.5 microg/g, and NPEOn, OPEOn and other compounds, such as coprostan and bisphenol A, in surface water and/or wastewater samples at concentrations ranging from the ppt to ppb levels.

Biomarker study of a municipal effluent dispersion plume in two species of freshwater mussels

The toxicological effects of a primary-treated municipal effluent plume were investigated in two species of freshwater mussels, Elliptio complanata and Dreissena polymorpha, exposed for 62 days at sites upstream and downstream of an effluent outfall in the St. Lawrence River (Quebec, Canada). Levels of metallothioneins (MT), cytochrome P4501A1 activity, DNA damage, total lipids, relative levels of vitellins, and phagocytic activity (in E. complanata hemocytes) were determined after the exposure period. A parallel analysis measured heavy metals and coprostanol in mussel tissues. The results show that significant levels of coprostanol and some metals (specifically, Cu, Hg, Sb, Se, and Zn) had accumulated in mussels caged 5 km downstream of the effluent plume. Mixed-function oxidase activity, MT in gills, total lipids, DNA damage (in D. polymorpha only), and total hemolymph bacteria (in E. complanata only) had increased in these mussels, while levels of total cadmium (Cd), MT in digestive glands or whole soft tissues, phagocytic activity, and DNA damage in the digestive gland (in E. complanata only) were diminished. The exposure of mussels to surface waters contaminated by a municipal effluent led to many stress responses, depending on both the tissues and the species being examined.