permetrin

Permethrin, also spelled permetrin in some sources, is a synthetic pyrethroid insecticide and acaricide used to control a wide range of pests in agriculture, in consumer products, and in public health. It is a mixture of stereoisomers and is active against many insects and mites while being relatively less toxic to mammals at typical exposures.

Permethrin acts by altering the function of voltage-gated sodium channels in nerve cells, keeping them open longer and causing repetitive nerve firing, paralysis, and death in insects. The selectivity is mainly due to differences in metabolism and nervous system sensitivity between insects and mammals.

Common uses include control of agricultural pests, household and garden applications, and topical treatments for humans in the management of head lice and scabies (creams and shampoos). Veterinary products use permethrin for mites and fleas, and it is also incorporated into insecticide-treated nets and clothing for vector control. It is frequently combined with piperonyl butoxide to inhibit insect detoxification enzymes and enhance efficacy.

Safety and environmental considerations: In humans, permethrin at approved doses is usually well tolerated but can cause skin irritation or allergic reactions; systemic toxicity is rare. It is highly toxic to cats and must be used with caution around pets. It is also highly toxic to fish and aquatic invertebrates, and environmental residues may pose concerns. The compound degrades in sunlight and soil, with persistence depending on formulation and exposure conditions.

Resistance and regulation: Some pest populations have developed resistance through mutations in sodium channels or enhanced detoxification. Regulatory guidance varies by country and product type, with some restrictions on formulations and usage near water or food contact.