Assessment of source water contamination by estrogenic disrupting compounds in China

Combined effects of estrogenic chemicals with the same mode of action using an estrogen receptor binding bioassay

The increasing amounts of various estrogenic chemicals coexisting in the aquatic environment may pose environmental risks. While the concept of estradiol equivalent (EEQ) has been frequently applied in studying estrogenic mixtures, few experiments have been done to prove its reliability. In this study, the reliability of EEQ and the related model concentration addition (CA) was verified based on the two-hybrid recombinant yeast bioassay when all mixture components had the same mode of action and target of action. Our results showed that the measured estrogenic effects could be well predicted by CA and EEQ for all laboratory-made mixtures using two designs, despite the varying estrogenic activity, concentration levels and ratios of the test chemicals. This suggests that when an appropriate endpoint and its relevant bioassay are chosen, CA should be valid and the application of EEQ in predicting the effect of non-equi-effect mixtures is feasible.

Assessment of estrogen disrupting potency in animal foodstuffs of China by combined biological and chemical analyses

Food has been documented as one of major routes for human exposure to environmental estrogens (EEs), but information on the occurrence of EEs in animal foodstuffs is still scarce. This study analyzed estrogenic activity in 16 types of animal foodstuffs (n=142) collected from four cities (Wuhan, Guangzhou, Wenzhou and Yantai) of China by combined yeast estrogen screen (YES) bioassay and chemical analysis. By bioassay, all samples' extracts were found to induce estrogenic activities and the bioassay-derived 17β-estradiol equivalent (EEQbio) ranged from 8.29 to 118.32ng/g. In addition, the samples were analyzed by liquid chromatography coupled to tandem mass spectrometry for further chemical analysis. 17β-Estradiol was found in all samples in this survey at levels of 0.44 to 15.04ng/g. All samples had 33.1% detection rate of 17α-ethinylestradiol (EE2), and the maximum concentration was 2.80ng/g. Bisphenol A and 4-nonylphenols were detected in 83.8% and 83.1% of samples, with concentrations up to 12.56ng/g and 35.76ng/g, respectively. However, the concentrations of estrone, diethylstilbestrol and 4-t-octylphenol were found to be below the limit of detection. A comparison of EEQbio measured from the YES assay and EEQchem calculated from chemical analysis showed good correlation (R(2)=0.84). Based on the results, the YES assay can be used as a rapid pre-screening method for monitoring the levels of estrogenic activity in large numbers of animal foodstuffs, and chemical analysis used in combination can be used for the identification of specific EEs.

Levels of endocrine disrupting compounds in South China Sea

The occurrence of estrogens in the aquatic environment has become a major concern worldwide because of their strong endocrine disrupting potency. In this study, concentrations of four estrogenic compounds, estrone (E1), 17β-estradiol (E2), 17α-ethynylestradiol (EE2), estriol (E3) were determined with liquid chromatography-tandem mass spectrometry analyses in surface water from South China Sea, and distributions and potential risks of their estrogenic activity were assessed. The estrogenic compounds E1, E2 and E3 were detected in most of the samples, with their concentrations up to 11.16, 3.71 and 21.63 ng L(-1). However, EE2 was only detected in 3 samples. Causality analysis, EEQ values from chemical analysis identified E2 as the main responsible compounds. Based on the EEQ values in the surface water, high estrogenic risks were in the coastal water, and low estrogenic risks in the open sea.

In vitro interactions between 17β-estradiol and DNA result in formation of the hormone-DNA complexes

Beyond the role of 17β-estradiol (E2) in reproduction and during the menstrual cycle, it has been shown to modulate numerous physiological processes such as cell proliferation, apoptosis, inflammation and ion transport in many tissues. The pathways in which estrogens affect an organism have been partially described, although many questions still exist regarding estrogens' interaction with biomacromolecules. Hence, the present study showed the interaction of four oligonucleotides (17, 20, 24 and/or 38-mer) with E2. The strength of these interactions was evaluated using optical methods, showing that the interaction is influenced by three major factors, namely: oligonucleotide length, E2 concentration and interaction time. In addition, the denaturation phenomenon of DNA revealed that the binding of E2 leads to destabilization of hydrogen bonds between the nitrogenous bases of DNA strands resulting in a decrease of their melting temperatures (Tm). To obtain a more detailed insight into these interactions, MALDI-TOF mass spectrometry was employed. This study revealed that E2 with DNA forms non-covalent physical complexes, observed as the mass shifts for app. 270 Da (Mr of E2) to higher molecular masses. Taken together, our results indicate that E2 can affect biomacromolecules, as circulating oligonucleotides, which can trigger mutations, leading to various unwanted effects.

Emission estimation and multimedia fate modeling of seven steroids at the river basin scale in China

Steroids are excreted from humans and animals and discharged with wastewaters into the environment, resulting in potential adverse effects on organisms. Based on the excretion rates from different groups of humans and animals, the emissions of seven steroids (estrone (E1), 17β-estradiol (E2), estriol (E3), testosterone (T), androsterone (A), progesterone (P), and cortisol (C)) were comprehensively estimated in 58 river basins of whole China, and their multimedia fate was simulated by using a level III fugacity multimedia model. The results showed that higher emission densities for the steroids were found in the river basins of east China than in west China. This distribution was found to be generally similar to the distribution of Gross Domestic Product (GDP) across China. E3, A, and P displayed higher emission densities than the other steroids in most of the river basins. The total excretion of steroids by humans and animals in China was estimated to be 3069 t/yr. The excretion of steroids from animals was two times larger than that from humans. After various treatments, the total emission of steroids was reduced to 2486 t/yr, of which more than 80% was discharged into the water compartment. The predicted concentrations in water were within an order of magnitude of the measured concentrations available in the literature. Owing to wastewater irrigation, more steroid mass loadings in agricultural soil were found in the basins of Haihe River and Huaihe River in comparison with the other river basins. To the best of our knowledge, this is the first report on the emissions and multimedia fate of seven steroids in the river basins of China.

Pyruvate carboxylase as a sensitive protein biomarker for exogenous steroid chemicals

Assessing protein responses to endocrine disrupting chemicals is critical for understanding the mechanisms of chemical action and for the assessment of hazards. In this study, the response of the liver proteome of male rare minnows (Gobiocypris rarus) treated with 17β-estradiol (E2) and females treated with 17α-methyltestosterone (MT) were analyzed. A total of 23 and 24 proteins were identified with differential expression in response to E2 and MT, respectively. Pyruvate carboxylase (PC) was the only common differentially expressed protein in both males and females after E2- and MT-treatments. The mRNA as well as the protein levels of PC were significantly down-regulated compared with that of the controls (p < 0.05). Our results suggest that endocrine disruptors interfere with genes and proteins of the TCA cycle and PC may be a sensitive biomarker of exposure to exogenous steroid chemicals in the liver of fish.

Estrogen receptor affinity chromatography: a new method for characterization of novel estrogenic disinfection by-products

To identify the unknown estrogenic disinfection by-products (DBPs) from the chlorination extract, an effective method based on affinity chromatography with immobilized human recombinant estrogen receptor α (ERα) was developed, which has an advantage in targeting different potential estrogenic compounds from mixed sample simultaneously by comparing their relative binding activities to ER. The new method worked well for six known environmental estrogens. To further test the validity of this method for unknown chemicals, six DBPs of diethylstilbestrol (DES) with relatively strong ER binding affinity after chlorination were isolated and identified. It was found that except for 2-chloro-DES which showed 1.36 times stronger binding affinity than DES, most of the by-products bound to ER much more weakly than DES. All these seven by-products induced a dose-dependent transcriptional activation in two-hybrid-yeast assays. Z,Z-dienestrol (DE) and 2-chloro-DES, which exhibiting the weakest and the strongest binding affinity, were further tested for their transcriptional potential as 0.00243 and 0.014 compared to DES, respectively. However, they were still potential harmful environmental estrogenic disruptors as their estrogenic activities were much stronger than that of bisphenol A (BPA). These results demonstrated that the new method can help to screen unknown estrogenic compounds from mixture more efficiently.

Distribution and seasonal variation of estrogenic endocrine disrupting compounds, N-nitrosodimethylamine, and N-nitrosodimethylamine formation potential in the Huangpu River, China

Detection of estrogenic endocrine disrupting compounds (EDCs) and N-nitrosodimethylamine (NDMA) in drinking water has led to rising concerns. There are, however, a paucity of studies on the distribution and seasonal variation of NDMA and NDMA formation potential (NDMA-FP) in natural waters, especially in China. For EDCs, limited studies have investigated the distribution and seasonal variation of estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethinylestradiol (EE2), technical-nonylphenols (t-NP), and bisphenol A (BPA) in Shanghai. In this study, water samples were collected from 11 sampling sites along the Huangpu River in 2012. The distribution and seasonal variation of EDCs, NDMA, and NDMA-FP were investigated. The results showed that all of the 11 sampling sites were contaminated by the target compounds. Compared with E2 and EE2, higher E1 and E3 concentrations were usually detected in the Huangpu River. The values of 17β-estradiol equivalents (EEQ) suggest a high possibility of endocrine effects on exposed organisms in the Huangpu River. NDMA-FP and t-NP were the dominant contaminants among the eight target compounds. The detection rates of the target compounds and their concentrations were both higher in dry seasons than in wet seasons. Higher concentrations of target compounds were observed in urban sampling sites near drainage outlets, and also in suburban sampling sites where intensive livestock farming and farmlands were located.

Ecological risk of nonylphenol in China surface waters based on reproductive fitness

It has been recognized that ecological risk assessment based on traditional endpoints of toxicity are unable to provide adequate protection because some chemicals may affect reproductive fitness of aquatic organisms at much lower concentrations. In this paper, predicted no effect concentrations (PNECs) for 4-nonylphenol (NP) were derived based either on endpoints of survival, development, and growth or on some nonlethal biomarkers of reproduction, biochemical and molecular biology data. The PNECs derived from reproductive lesion ranged from 0.12 to 0.60 μg NP L(-1), which was significantly lower than those derived from other endpoints. An assessment of ecological risks posed by NP to aquatic organisms in surface waters of China was conducted based on concentration levels of NP in 16 surface waters of 4 major river basins and PNECs derived from reproductive fitness by a tiered ecological risk assessment (ERA). The results showed that 14.2% and 76.5% of surface waters in China may have ecological risks resulting from reproductive fitness if the thresholds of protection for aquatic organisms were set up as 5% (HC5) and 1% (HC1), respectively. The risks were significantly greatest in the Yangtze River Basin than in other major river basins. In comparison with the risks assessed based on traditional endpoints, such as lethality, for those chemicals causing adverse effects on reproduction due to modulation of endocrine function, to be protective of ecosystem structure and function, lesser PNECs, based on sublethal effects of reproduction, were appropriate.

Metal ions-based immunosensor for simultaneous determination of estradiol and diethylstilbestrol

Environmental estrogens (EEs) can cause various endocrine diseases. Herein, we designed an ultrasensitive electrochemical immunosensor for simultaneous detection of two typical EEs, estradiol and diethylstilbestrol. These two analytes were immobilized on graphene sheet (GS) modified glassy carbon electrode (GCE). Amino-group functionalized mesoporous Fe3O4 (Fe3O4-NH2) was loaded with Pb(2+) or Cd(2+), and then incubated with estradiol and diethylstilbestrol antibodies, respectively. Using an electrochemical analysis technique, two well-separated peaks were generated by the redox reaction of Pb(2+) or Cd(2+), making the simultaneous detection of two analytes on the electrode possible. Subsequently, square wave anodic stripping voltammetry (SWASV) and electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical behaviors of the immunosensor. Under optimized conditions, the SWASV peak currents were proportional to the concentrations of estradiol and diethylstilbestrol in the range from 0.050 pg mL(-1) to 100 ng mL(-1) and 1.0 pg mL(-1) to 100 ng mL(-1), respectively. The immunosensor exhibited highly sensitive response to estradiol with a detection limit of 0.015 pg mL(-1) and diethylstilbestrol with a detection limit of 0.38 pg mL(-1). Furthermore, the immunosensor was satisfactorily employed to detect estradiol and diethylstilbestrol simultaneously in water samples.

Occurrence, removal and bioaccumulation of steroid estrogens in Dianchi Lake catchment, China

The occurrence, removal and bioaccumulation of steroid estrogens such as the natural estrone (E1), 17β-estradiol (E2) and estriol (E3), as well as the synthetic 17α-ethynylestradiol (EE2) were investigated in Dianchi Lake catchment, China. The results show that traditional secondary treatment processes in eight sewage treatment plants (STPs) of Kunming were not efficient enough to completely remove steroid estrogens, but ultraviolet (UV) photodegradation in advanced treatment displayed more effectively for the removal of the residual compounds. The amount of total steroid estrogens (∑SEs) discharged to Dianchi Lake catchment by the eight STPs was 35.8g/day, in which STP-3 was the dominant source, accounting for 50.8%. Because of the pollution input from treated and untreated sewages, estrogens were widely detected in surface water and sediment samples collected from 21 inflow rivers of Dianchi Lake, 10 National Surface Water Quality Monitoring Sites of the lake itself and its unique outflow river, with the mean concentration of ∑SEs in the range of 5.3-798.2ng/L (water) and 3.7-202.4ng/g (dry weight, sediment), 1.5-39.2ng/L (water) and 2.7-20.9ng/g (sediment), and 4.2ng/L (water) and 6.6ng/g (sediment), respectively. Due to the continuous input of estrogens to Dianchi Lake from STPs and inflow rivers, present estrogen levels in various tissues of wild fish species sampled from the lake (2013) were higher than the values detected in the previous years (2009 and 2010). The bioaccumulation of steroid estrogens in wild fish species from different sampling sites was in the order of STP-5>Dianchi Lake (2013)>Dianchi Lake (2010)≈Dianchi Lake (2009)≫field control>laboratory control, which is mainly affected by exposure concentrations. By employing risk quotient (RQ), it is found that eco-toxicological risk of steroid estrogens in Dianchi Lake catchment was in a sequence of 22 rivers>effluents of eight STPs>Dianchi Lake (2013)>Dianchi Lake (2010), and high RQs were found in EE2, which should be controlled preferentially in this catchment.

β-estradiol 17-valerate affects embryonic development and sexual differentiation in Japanese medaka (Oryzias latipes)

β-estradiol 17-valerate (EV) is a synthetic estrogen widely used in combination with other steroid hormones in hormone replacement therapy drugs and is detected in natural waters. Although EV is known as an estrogenic chemical, there is still a lack of data on its developmental and reproductive toxicities in fish following exposure to EV during embryo-larval-, juvenile- and adult-life stages in Japanese medaka (Oryzias latipes). At the early life stage, the fertilized eggs of medaka were exposed to 1, 10, 100 and 1000 ng/L EV for 15 days, and hatched larval fish were continually exposed to the same concentration range for an additional 15 days. The results showed that exposure to 10 ng/L or above resulted in adverse effects on hatchability and time to hatching, and the number of hatched females was twice that of males at 10 ng/L or above. When the hatched fish were continually exposed to 1, 10 and 100 ng/L of EV for another 40 days, the hepatosomatic index (HSI) was increased in both males and females, and the gonadosomatic index (GSI) was decreased in females, and increased in males. Sex reversal was found in fish exposed to 1 ng/L and above. Quantitative real-time RT-PCR showed that mRNA levels of estrogen receptor α (ER-α) and vitellogenin-I (VTG-I) in the liver of females were significantly down-regulated, while those of vitellogenin-I (VTG-I) in the liver of males were significantly up-regulated at all concentrations. These findings suggest that EV is a reproductive toxicant and estrogenic chemical in both male and female fish.

Bioanalytical and instrumental analysis of estrogenic activities in drinking water sources from Yangtze River Delta

The estrogenic activities of source water from Yangtze River, Huaihe River, Taihu Lake and groundwater in Yangtze River Delta in the dry and wet season were determined by use of reporter gene assays based on African green monkey kidney (CV-1) cell lines. Higher estrogenic activities were observed in the dry season, and the estrogenic potentials in water samples from Taihu Lake were greater than other river basins. None of the samples from groundwater showed estrogen receptor (ER) agonist activity. The 17β-Estradiol (E2) equivalents (EEQs) of water samples in the dry season ranged from 9.41×10(-1) to 1.20×10(1) ng E2 L(-1). In the wet season, EEQs of all the water samples were below the detection limit as 9.00×10(-1) ng E2 L(-1) except for one sample from Huaihe River. The highest contribution of E2 was detected in Yangtze River as 99% of estrogenic activity. Nonylphenol (NP, 100% detection rate) and octylphenol (OP, 100% detection rate) might also be responsible for the estrogenic activities in water sources. Potential health risk induced by the estrogenic chemicals in source water may be posed to the residents through water drinking.