OBJECTIVESTo examine nonylphenol (NP) and 4-t-octylphenol (OP) concentrations and general water quality indicators along a river in the greater Tokyo area and to specify the distribution and origin of alkylphenols.

METHODSWater was sampled from the Edogawa River, a main river in the greater Tokyo area, which is a source of public drinking water; and the Sakagawa River system, a tributary of the Edogawa River. To determine alkylphenol in river water. NP and OP concentrations were quantified using gas chromatography-mass spectrometry (GC-MS).

RESULTSThe detection rates of NP above the detection limit were 100% in both rivers, and those of OP were 75.0% in the Edogawa River and 92.9% in the Sakagawa River system. The median NP and OP concentrations in the Edogawa River were 0.24 μg/1 and 0.066 μg/l, and those in the Sakagawa River system were 0.87 μg/l and 0.19 μg/l respectively. Alkylphenol concentrations are significantly higher in the Sakagawa River system than in the Edogawa River. In the Sakagawa River system, the NP and OP concentrations were highest in the water along the nonindustrial area with an underdeveloped sewerage system.

CONCLUSIONSNP and OP were detected widely in the Edogawa River and Sakagawa River system. Endocrine-disrupting chemical (EDC) pollution in a river by the inflow of urban wastewater was demonstrated. A systematic monitoring of alkylphenols in tributary rivers and streams as well as in main rivers will help control EDC pollution and protect the source of drinking water in urban areas.