Acetylthiocholine (ATC)--cleaving cholinesterase (ChE) activity as a potential biomarker of pesticide exposure in the Manila clam, Ruditapes philippinarum, of Korea.

The acetylthiocholine (ATC) - cleaving cholinesterase (ChE) activity in Manila clam, which is widely distributed throughout the coastal environment of Korea, was assayed as a potentially useful biomarker of organophosphorous pesticides (OPs). A clear dose-response relationship was determined between inhibited ChE in adductor muscle of clams and four OPs (methidathion, chlorpyrifos, diazinon, IBP) which are heavily used OPs in Korea. The measured EC(50)-24 h values of methidathion, chlorpyrifos, diazinon, and IBP for Ruditapes philippinarum were 7.16 μg l(-1), 0.34 mg l(-1), 3.01 mg l(-1), and 3.41 mg l(-1), respectively. In field studies, ChE activity in Manila clams collected from 23 stations in the mid-western coastal region demonstrated spatial variation with statistical differences. These results suggest that ChE activity in R. philippinarum is a potential biomarker for assessing organophosphorous pesticide contamination in coastal environments.