Fenthion

Fenthion is an organophosphate insecticide used widely to control a range of arthropod pests in agriculture and, in some regions, for public health applications such as mosquito control. It is formulated as emulsifiable concentrates, granules, and other ready-to-use products for application on crops including citrus, fruit, vegetables, and stored products.

Mechanism of action and metabolism: Fenthion acts as an acetylcholinesterase inhibitor, causing the accumulation of acetylcholine in the nervous system of insects and leading to overstimulation and death. It can be absorbed through the skin or by ingestion, and is metabolized in plants and animals to compounds such as fenthion sulfoxide and fenthion sulfone, which contribute to its toxicity.

Environmental and health considerations: Fenthion is highly toxic to non-target species, including birds, aquatic organisms, and beneficial insects. It poses risks of groundwater and surface water contamination through drift, runoff, or leaching. The compound is moderately persistent in the environment, degrading by hydrolysis and photolysis, with breakdown products that also retain toxic potential. Its volatility contributes to inhalation exposure and airborne drift under certain application conditions.

Regulatory status and safety: Because of its toxicity to wildlife and potential human health risks, fenthion has been heavily regulated or banned for many uses in numerous countries. When handling or applying fenthion, operators are advised to follow label instructions, use appropriate protective equipment, and minimize exposure. Reported symptoms of exposure include cholinergic effects such as excessive salivation, sweating, pupil constriction, slowed heart rate, muscle weakness, and in severe cases, seizures; medical consultation is recommended if exposure is suspected.