[Volatile organic compounds of the tap water in the Watarase, Tone and Edo River system].
OBJECTIVE
The chlorination of river water in purification plants is known to produce carcinogens such as trihalomethanes (THMs). We studied the river system of the Watarase, Tone, and Edo Rivers in regard to the formation of THMs. This river system starts from the base of the Ashio copper mine and ends at Tokyo Bay. Along the rivers, there are 14 local municipalities in Gunma, Saitama, Ibaragi and Chiba Prefectures, as well as Tokyo. This area is the center of the Kanto plain and includes the main sources of water pollution from human activities. We also analyzed various chemicals in river water and tap water to clarify the status of the water environment, and we outline the problems of the water environment in the research area (Fig. 1).


METHODS
Water samples were taken from 18 river sites and 42 water faucets at public facilities in 14 local municipalities. We analyzed samples for volatile organic compounds such as THMs, by gas chromatography mass spectrometry (GC-MS), and evaluations of chemical oxygen demand (COD) were made with reference to Japanese drinking water quality standards.


RESULTS
Concentrations of THMs in the downstream tap water samples were higher than those in the samples from the upperstream. This tendency was similar to the COD of the river water samples, but no correlation between the concentration of THMs in tap water and the COD in tap water sources was found. In tap water of local government C, trichloroethylene was detected.


CONCLUSIONS
The current findings suggest that the present water filtration plant procedures are not sufficient to remove some hazardous chemicals from the source water. Moreover, it was confirmed that the water filtration produced THMs. Also, trichloroethylene was detected from the water environment in the research area, suggesting that pollution of the water environment continues.
Department of Hygiene and Public Health, Graduate School of Human Sciences, Waseda University, Saitama.
Kimihide
K
Ohmichi
Masayoshi
M
Ohmichi
Kazuhiko
K
Machida
D002713:Chlorine / Q000009:adverse effects; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007564:Japan; D010100:Oxygen / Q000737:chemistry; D045483:Rivers; D014241:Trichloroethylene / Q000032:analysis; D022882:Trihalomethanes / Q000032:analysis*; D014835:Volatilization; D014867:Water / Q000737:chemistry* / Q000592:standards; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods / Q000592:standards; D014881:Water Supply
D022882:Trihalomethanes; D014874:Water Pollutants, Chemical; D014867:Water; D014241:Trichloroethylene; D002713:Chlorine; D010100:Oxygen