Evaluation of endocrine disruption and dioxin-like effects of organic extracts from sewage sludge in autumn in Beijing, China

Study on effective disposal and utilization of sewage sludge has recently been the target of growing interest in China. However, potential risks are associated with the use of sludge due to its contamination with toxic organics, heavy metals and pathogenic microorganisms. In this study, a screening assessment was conducted on sewage sludge samples collected from 17 different sewage treatment plants in Beijing, based on a batch of in vitro bioassays, including a set of recombinant gene yeast assays for endocrine disruption, and an ethoxy resorufin-O-deethylase (EROD) assay using H4IIE cells for aryl hydrocarbon receptor (Ah-R) agonistic activities. Our results suggested that moderate levels of estrogen receptor agonistic activities (0.9 ng E2.g(-1) to 6.8 ng E2.g(-1), dw), but relative higher androgen receptor antagonistic activities (nd to 45%), progestin receptor antagonistic activities (nd to 80%) and Ah-R agonistic activities (1390 to 6740 pg 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).g(-1), dw) were found in sewage sludge samples. However, there were no significant correlations between the toxic effects of sewage sludge and the sewage treatment processes. In addition, the 17 beta-estradiol (E2) equivalent quantity (EEQ) level of the sewage sludge was increased after the composting treatment, whereas the 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalent quantity (TEQ) level of sewage sludge composted was much lower than that of sewage sludge.