Impact of recent manure applications on natural estrogen concentrations in streams near agricultural fields.

Few studies on natural estrogens have been conducted in agricultural ecosystems. High (up to 58 ng/L) estrone concentrations were measured shortly after applications of manure in a small agricultural watershed. No other estrogens (17ß-estradiol, estrone or estriol) were detected afterward (first three rainfalls after applications). Results suggest that aquatic organisms in agricultural watersheds could be exposed to estrone shortly after manure applications, probably from leaching of land-applied animal wastes, but that this exposure would be short-lived.