Changes in estrogenic and androgenic activities at different stages of treatment in wastewater treatment works.

Estrogenic and androgenic activities of wastewater were determined during treatment in five wastewater treatment works (WWTWs) in the Untied Kingdom. With one exception, both estrogenic and androgenic activities decreased markedly as wastewater progressed through the plants; removal rates were generally 70% or higher, sometimes reaching 100%. Most of the reduction in activity occurred during secondary (biological) treatment. In both influents and effluents, estrogenic and androgenic activities were appreciably lower in samples collected in August, when the amount of rain had been substantial, compared with samples collected in April and May. Most final effluents contained very low (or nondetectable) estrogenic activity (undetectable to 13 ng/L of estradiol equivalents) and androgenic activity (undetectable to 143 ng/L of dihydrotestosterone [DHT] equivalents), although one (from a WWTW that had only primary treatment) contained relatively high activities (40 ng/L of estradiol equivalents; 4,033 ng/L of DHT equivalents). The type of treatment available at the various WWTWs also affected the activity of the final effluent. The biological significance of these results will depend upon which chemicals contribute to the estrogenic and androgenic activities, because of widely different potencies of different estrogenic chemicals, and on the degree of dilution of the effluents in their receiving waters.