Clinical and Post Mortem Aspects of Methomyl Intoxication

Abstract

Methomyl is a carbamate pesticide that induces acute cholinergic poisoning in mammals by reversible inhibiting acetylcholinesterase activity. In the Netherlands, methomyl is not legally registered for use as an active substance in pesticides. However, intoxications with non-registered pesticides have been reported before. The goal of this review, therefore, is to summarize clinical and post-mortem aspects that should be considered in forensic investigations of suspected methomyl intoxications. In clinical and post mortem situations the inhibition of (acetyl)cholinesterase activity is used as a biomarker in methomyl intoxications and methomyl is analyzed in biological samples. In clinical settings the kinetic pattern of the acetylcholinesterase enzyme activity can be used to differentiate between carbamates and organophosphates. Post mortem concentrations of methomyl are probably highest in cerebrospinal fluid and vitreous humor. Hairs might be used to detect past exposure to methomyl. However the inhibition of (acetyl)cholinesterase by carbamates is reversible and post mortem reactions decrease the concentrations of methomyl in biological samples. Therefore, further research in humans is needed on probable alternative analytical markers like methomyl metabolites and factors associated with oxidative stress caused by methomyl intoxication. Additionally, data on possible relationships between amount of methomyl ingested, methomyl concentration in blood, and blood (acetyl)cholinesterase activities are lacking.