Journal of Water Supply: Research and Technology—AQUA Vol 57 No 3 pp 143–151 © IWA Publishing 2008 doi:10.2166/aqua.2008.031
The behaviour and cholinesterase inhibitory activity of fenthion and its products by light and chlorination
Maiko Tahara, Reiji Kubota, Hiroshi Tokunaga, Tetsuji Nishimura and Hiroyuki Nakazawa
Division of Environmental Chemistry, National Institute of Health Sciences, Kamiyoga 1-18-1, Setagaya-ku, Tokyo, 158-8501, Japan Tel.:+81-3-3700-9346 Fax: +81-3-3700-9346 nishimur@nihs.go.jp
Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Hoshi University, Ebara 2-4-41, Shinagawa-ku, Tokyo, 142-8501, Japan
ABSTRACT
We established a method for quantitative analysis of fenthion (MPP) and its related compounds in water samples, using solid-phase extraction and liquid chromatography/mass spectrometry. With this method, the values of the limit of quantification ranged from 0.2 to 100 ng l-1. Using this method, we examined the fate of MPP in water and the products produced by light irradiation and chlorination. MPP decreased gradually and reached 50% of the initial concentration after 48 hours in water. In particular, MPP-sulfoxide was formed. With light irradiation, MPP decomposed immediately into MPP-sulfoxide, O,O-Dimethyl S-[3-methyl-4-(methylthio)phenyl]phosphorothioate and other compounds. With chlorination, MPP decomposed into MPP-sulfoxide, MPP-sulfone, and their oxons. The concentration of oxons increased in a time-dependent manner. In their effects on organisms, MPP, MPP-sulfoxide and MPP-sulfone showed weak inhibitory activity to cholinesterase, whereas their oxons showed strong activity. It is feared that MPP and its products exist in environmental water and are produced by the disinfection treatment process. Comprehensive evaluation of the toxicity of MPP and its related compounds is important in order to understand the effects of MPP on ecosystems and human health.
Keywords: ChE activity; chlorination; light irradiation; MPP; oxidized products; water
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