Estrogenic potency of effluent from two sewage treatment works in the United Kingdom

Rainbow trout were exposed for 3 weeks (in a Row-through system) to various dilutions of treated effluent (25, 50. 75, and 100%) from Harpenden and Ch elmsford sewage treatment works (STW) during November 1994 and August 1996, respectively, and the induction of plasma vitellogenin was measured. Signi ficant (p < 0.05) increases in plasma vitellogenin concentrations occurred in fish held in affluent from Harpenden STW at concentrations of 50% and ab ove. At Chelmsford STW, the effluent appeared to be more potent. causing in duction of vitellogenin in fish at concentrations as low as 25% (compared w ith 50% for the Harpenden effluent). Exposure to lower concentrations of ef fluent emanating from Chelmsford in April of the following year indicated t hat estrogenic activity was diluted to no-effect levels at this STW at conc entrations between 12 and 25%.