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. ► We determined ChE activity of Manila clam to be a suitable biomarker for OPs. ► Clear dose-response relationship was shown between ChE activity of clam and OPs. ► Clams from the mid-western coast of Korea indicated spatial variation in ChE activity. ► IBP concentration showed a significant relationship with ChE activity in Manila clam. ► ChE activity of clam can be useful biomarker of OPs in the coastal environment.