Estrogenic metabolites of alkylphenol polyethoxylates in secondary sewage effluents and rivers

Degradation products of nonionic surfactants of the nonylphenol polyethoxyl ate type (NPnEO) were reported recently to be estrogenic to fish at low mic rogram per litre concentrations. These estrogenic metabolites, including no nylphenol (NP), nonylphenol monoethoxylate (NP1EO) and nonylphenol diethoxy late (NP2EO) as well as their corresponding carboxylic acids (NP1EC and NP2 EC), were measured during 1997 and 1998 in sewage effluents and ambient wat ers in Switzerland in order to assess the effects of risk reduction measure s introduced in 1986. Lipophilic metabolites (NP+NP1EO+NP2EO) were found in the examined secondary sewage effluents mostly at concentrations from 1 to 5 mug/L, while elevated levels were found in those sewage treatment plants which receive industrial effluents from textile finishing plants. The conc entrations of the lipophilic nonylphenolic compounds in rivers ranged mainl y from 0.05 to 0.3 mug/L with NP being most abundant. The total concentrati on of the nonylphenoxy carboxylic acids was significantly higher than that of the lipophilic metabolites. Despite a significant decrease of the enviro nmental exposure levels of all nonylphenolic compounds subsequent to the in troduction of risk reduction measures, the total concentration of estrogeni c metabolites often exceeded the predicted no effect concentration (PNEC) o f 0.33 mug/L proposed in a risk assessment report to the European Union.