engleski

Estrogenic metabolites of alkylphenol polyethoxylates in secondary sewage effluents and rivers

Degradation products of nonionic surfactants of the nonylphenol polyethoxylate type (NPnEO) were reported recently to be estrogenic to fish at low microgram per liter concentrations. These estrogenic metabolites, including nonylphenol (NP), nonylphenol monoethoxylate (NP1EO) and nonylphenol diethoxylate (NP2EO) as well as their corresponding carboxylic acids (NP1EC and NP2EC), were measured during 1997 and 1998 in sewage effluents and ambient waters in Switzerland in order to assess the effects of risk reduction measures introduced in 1986. Lipophilic metabolites (NP+NP1EO+NP2EO) were found in the examined secondary sewage effluents mostly at concentrations from 1 to 5 mg/L, while elevated levels were found in those sewage treatment plants, which receive industrial effluents from textile finishing plants. The concentrations of the lipophilic nonylphenolic compounds in rivers ranged mainly from 0.05 to 0.3 mg/L with NP being most abundant. The total concentration of the nonylphenoxy carboxylic acids was significantly higher than that of the lipophilic metabolites. Despite a significant decrease of the environmental exposure levels of all nonylphenolic compounds subsequent to the introduction of risk reduction measures, the total concentration of estrogenic metabolites often exceeded the predicted no effect concentration (PNEC) of 0.33 mg/L proposed in a risk assessment report to the European Union.

Nonionic surfactants; Estrogenic metabolites; Nonylphenol; Secondary sewage effluents; Rivers

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