Toxicological profile of pollutants in surface water from an area in Taihu Lake, Yangtze Delta.

The environment in urbanized areas is often contaminated with a complex mixture of toxic compounds originating from industries, agriculture and private households. Most of the contaminants end up in surface waters, such as lakes, rivers and finally the sea. Toxic contaminants may disturb the biological condition of aquatic ecosystems and be harmful for humans, if they are transported to human food or drinking water. A variety of biological tests have been introduced for monitoring the toxicological profile of aquatic ecosystems. In the present investigation, genotoxic, hormone disrupting and Ah-receptor activity was analyzed in water collected in January 1999 at Meiliang Bay, Taihu Lake, China, near to the city of Wuxi in the Shanghai area. Significant mutagenic activity could be detected in water extracts with the Salmonella/microsome assay and the arabinose resistance test. Frame shift mutations were the predominant mode of action. Ah-receptor active compounds were detected by using a luciferase reporter gene assay (CALUX-assay). The estimated toxic equivalent factor-values ranged between 134 and 232 pg TCCD-equivalents per liter lake water. The estrogen-like potential of Taihu water was estimated with two luciferase reporter gene assays using transgenic human cell lines expressing estrogen receptor alpha. Estradiol equivalents obtained with water extracts were in the range of 2.2-12.1 ng/l. We also analyzed the concentrations of 17-beta-estradiol and ethinylestradiol in the extracts using a high-pressure liquid chromatography-method. The values obtained correlated with the biologically determined estradiol equivalents, indicating that the estrogenic activity is mainly due to natural and synthetic hormones rather than xenoestrogens.