[Changes in the concentrations of chlornitrofen (CNP) and CNP-amino in river and faucet water in Niigata, Japan].

It has been reported that the standardized mortality ratios (SMRs) of biliary tract cancer (BTC) (female gallbladder cancer (GBC) in particular) are high in the Niigata plain and low in other parts of Niigata Prefecture. Based on epidemiological studies, the presence of environmental water pollution by agricultural chemicals is likely to be associated with the occurrence of GBC, and one of the most suspected of these is a diphenylether herbicide, chlornitrofen (CNP). The purpose of the present study was to investigate whether or not there was a difference in concentrations of CNP and its reduction product (CNP-amino) in river and faucet water between Niigata and Joetsu Cities, which are located in the Niigata plain and another part of Niigata, respectively. By employing a new method for CNP and CNP-amino extraction, the detection of CNP and CNP-amino was undertaken by using a gas-chromatograph with an electron-capture detector. The maximum levels of CNP concentrations were 871 and 554 ng/l in river and faucet water, respectively on May 6, 1992 in Niigata City. The concentration of CNP in faucet water was well correlated with that in river water. In Joetsu City, the maximum concentration in river water was 183 ng/l on May 6 and had decreased rapidly towards the background level on July 29, 1992. As to the concentrations of CNP in faucet water in Joetsu City, they fluctuated between the levels of 2 and 9 ng/l. In the case of CNP-amino concentrations in faucet water, a clear-cut difference was evident between the two cities; 384 ng/l in Niigata and under the quantity limit in Joetsu.(ABSTRACT TRUNCATED AT 250 WORDS)