Malathion

Malathion is an organophosphate insecticide used to control a wide range of pests in agriculture, horticulture, forestry, and public health programs, including mosquito control. It is formulated as emulsifiable concentrates, dusts, granules, or ready-to-use solutions and can be applied by ground or aerial methods. In some regions it is sold for home pest control.

Mode of action and toxicity: Malathion inhibits acetylcholinesterase, causing accumulation of acetylcholine and overstimulation of cholinergic nerves. Signs range from headaches and dizziness to nausea, sweating, and muscle twitching; higher exposures can be life-threatening. The metabolite malaoxon is more potent and can contribute to toxicity.

Environmental fate and regulation: Malathion degrades in air, water, and soil through hydrolysis, photolysis, and microbial action. Malaoxon is a more toxic oxidation product formed in some organisms. It is generally more toxic to aquatic organisms than to mammals, and drift or runoff can contaminate water bodies.

Safety and regulation: Use is regulated by national and regional authorities. Some places restrict or ban consumer products, while professional applications require training and protective equipment. Label directions, proper dermal and inhalation protection, and pre-harvest interval guidance help minimize risks. Residue levels in foods are monitored, and safety measures emphasize reducing exposure to non-target species.

Impact and use: Malathion residues are typically low when used according to label instructions, but exposure can occur via treated produce or drift. It remains one of the most widely used insecticides worldwide, though its use is increasingly restricted where non-target effects or environmental concerns are prioritized.