Exposure evaluation is a crucial step for quantitative risk assessment of methomyl.

Methomyl, methyl N-[[(methylamino)carbonyl]oxy]ethanimidothioate is a carbamate insecticide with anticholinesterase activity. As a broad spectrum insecticide, it is one of the most frequently used pesticides in tangerine orchards in Thailand. Although methomyl is said to be rapidly eliminated from experimental animals (1) high incidence of acute poisonings was reported among patients occupationally exposed to a powder formulation of methomyl (2, 3).