title: Bioassay of estrogenic activity of effluent and influent in a farm wastewater treatment plant using an in vitro recombinant assay with yeast cells.
abstract: OBJECTIVE
  Environmental estrogens at an elevated concentration are known to produce adverse effects on human and animal life. However, the majority of researches have been focused on industrial discharges, while the impact of livestock wastes as a source of endocrine disrupters in aquatic environments has been rarely elucidated. In order to investigate the contribution of environmental estrogens from livestock, the estrogenic activity in water samples from a farm wastewater treatment plant was analyzed by a recombinant yeast screening method.
  
  
  METHODS
  The extracts prepared from 15 selected water samples from the farm wastewater treatment plant, among which 6 samples were from pre-treatment section (influents) and 9 from post-treatment section (effluents), were analyzed for estrogenic activity by cellar bioassay. Yeast cells transfected with the expression plasmid of human estrogen receptor and the Lac Z reporter plasmid encoding beta-galactossidase, were used to measure the estrogen-like compounds in the farm wastewater treatment plant.
  
  
  RESULTS
  The wastewater samples from influents showed a higher estrogenic potency than the effluent samples showing a low induction of beta-galactossidase relative to solvent control condition. By comparison with a standard curve for 17 beta-estradiol (E2), estrogenic potency in water samples from the influents was calculated as E2-equivalent and ranged from 0.1 to 150 pM E2-equivalent. The estrogenic potency in water samples from the effluents was significantly lower than that in the influents, and 7 water samples had less detectable limit in the total of 9 samples.
  
  
  CONCLUSIONS
  Yeast bioassay of estrogenic activity in most of the samples from the farm wastewater after disposal by traditional sewage treatment showed negative results.
authors.affiliation: Department of Preventive Medicine, Medical College, Yangzhou University, Yangzhou 225001, Jiangsu, China. Lxm109@yahoo.com
authors.forename: Xiang-Ming
authors.initials: XM
authors.lastname: Li
authors.forename: Fang-Ni
authors.initials: FN
authors.lastname: Luo
authors.forename: Gui-Xia
authors.initials: GX
authors.lastname: Liu
authors.forename: Ping-Ting
authors.initials: PT
authors.lastname: Zhu
mesh_terms: D000383:Agriculture; D001681:Biological Assay / Q000379:methods*; D004305:Dose-Response Relationship, Drug; D004967:Estrogens / Q000737:chemistry / Q000633:toxicity*; D005818:Genetic Engineering; D007220:Industrial Waste / Q000032:analysis; D010957:Plasmids / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000235:genetics*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D004967:Estrogens; D007220:Industrial Waste; D014874:Water Pollutants, Chemical