Exploring potential contributors to endocrine disrupting activities in Taiwan's surface waters using yeast assays and chemical analysis.

Surface waters serve as sinks for anthropogenic contaminants, including naturally occurring hormones and a variety of synthetic endocrine active substances. To investigate the presence of endocrine active contaminants in the aquatic environment in Taiwan, river water and suspended solids were analyzed by yeast assays to examine the distribution of estrogenic, androgenic, and aryl hydrocarbon receptor agonist activities. The results showed that dry-season river samples exhibited strong estrogenic and aryl hydrocarbon receptor agonist activities, but no androgenic activity was detected. Owing to the ubiquitous detection of estrogenic activities in Taiwan's surface waters, samples were further subjected to liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis for quantification of selected estrogenic compounds. LC-MS/MS results indicated that natural estrogens, such as estrone and 17ß-estradiol were often the most contributing compounds for the bioassay-derived estrogenic activities due to their strong estrogenic potencies and high detection frequencies, whereas high concentrations of bisphenol A and nonylphenol also posed a threat to the aquatic ecosystems in Taiwan. Water samples eliciting strong estrogenic activities were further fractionated using high performance liquid chromatography, and significant estrogenic activities were detected in fractions containing estrone, 17ß-estradiol, 17α-ethynylestradiol, and bisphenol A. Also, the presence of unidentified estrogenic compounds was found in few river water samples. Further identification of unknown endocrine active substances is necessary to better protect the aquatic environment in Taiwan.

Monitoring of xenobiotic ligands for human estrogen receptor and aryl hydrocarbon receptor in industrial wastewater effluents.

Industrial wastewater contains a variety of toxic substances, which may severely contaminate the aquatic environment if discharged without adequate treatment. In this study, effluents from a thin film transistor liquid crystal display wastewater treatment plant and the receiving water were analyzed by bioassays and liquid chromatography-tandem mass spectrometry to investigate the presence of estrogenic compounds, aryl hydrocarbon receptor (AhR) agonists, and genotoxicants. Xenobiotic AhR agonists were frequently detected and, in particular, strong AhR agonist activity and genotoxicity were found in the suspended solids of the aeration tank outflow. The high AhR agonist activity in the final effluent (FE) and the downstream river water suggested that the treatment plant failed to remove the wastewater-related AhR agonists. In contrast, although significant estrogenic potency could be detected in raw wastewater or effluents from different treatment processes, the FE and the receiving river water exhibited no or weak estrogenicity. Instrumental analysis showed that bisphenol A was often detected in water samples. However, the investigated estrogenic compounds could only account for a small portion of the estrogenicity in the collected samples. Therefore, further investigation is necessary to identify the major estrogenic compounds and AhR agonist contaminants in the wastewater effluents.

Occurrence of aryl hydrocarbon receptor agonists and genotoxic compounds in the river systems in Southern Taiwan.

Water and sediment samples from river systems located in Southern Taiwan were investigated for the presence of aryl hydrocarbon receptor (AhR) agonists and genotoxicants by a combination of recombinant cell assays and gas chromatography-mass spectrometry analysis. AhR agonist activity and genotoxic response were frequently detected in samples collected during different seasons. In particular, dry-season water and sediment samples from Erren River showed strong AhR agonist activity (201-1423 ng L(-1) and 1374-5631 ng g(-1) ß-naphthoflavone equivalents) and high genotoxic potential. Although no significant correlation was found between AhR agonist activity and genotoxicity, potential genotoxicants in sample extracts were suggested to be causative agents for yeast growth inhibition in the AhR-responsive reporter gene assay. After high performance liquid chromatography fractionation, AhR agonist candidates were detected in several fractions of Erren River water and sediment extracts, while possible genotoxicants were only found in water extracts. In addition, polycyclic aromatic hydrocarbons, the typical contaminants showing high AhR binding affinity, were only minor contributors to the AhR agonist activity detected in Erren River sediment extracts. Our findings displayed the usefulness of bioassays in evaluating the extent of environmental contamination, which may be helpful in reducing the chances of false-negative results obtained from chemical analysis of conventional contaminants. Further research will be undertaken to identify major candidates for xenobiotic AhR agonists and genotoxicants to better protect the aquatic environments in Taiwan.