Dichlorvos (DDVP)

Dichlorvos was developed by Shell Chemical in the 1950s and became a major household and agricultural insecticide, particularly valued for its rapid knockdown activity against flying insects [1]. DDVP pest strips (resin strips impregnated with DDVP that slowly volatilize) became popular for controlling cockroaches and flies in homes, restaurants, and food storage areas. DDVP flea collars were widely used on pets [2]. EPA conducted multiple reviews of DDVP over the decades, ultimately restricting most household uses and placing it under a Toxics Release Inventory reporting requirement. Agricultural uses on certain crops remain registered [1]. DDVP is among the organophosphates most efficiently absorbed through skin [2].

People using DDVP pest strips in enclosed or poorly ventilated areas inhale volatilized DDVP — the intended release mechanism of pest strips creates significant indoor air DDVP levels [1]. Flea collar use results in dermal DDVP exposure to pets and to people, particularly children, who handle pets [2]. Agricultural workers applying DDVP sprays face inhalation and dermal exposure [1]. Residues on treated crops represent a dietary exposure pathway for agricultural produce [2].

Dichlorvos is a direct-acting (non-pro-drug) organophosphate — it does not require metabolic activation to inhibit acetylcholinesterase [1]. It forms a stable phosphorylated enzyme complex that 'ages' within hours, after which oxime antidote treatment becomes ineffective [2]. Cholinergic toxidrome (SLUDGE, muscle fasciculations, seizures in severe cases) occurs at higher doses. IARC classifies DDVP as Group 2B possible human carcinogen based on leukemia and solid tumor induction in rodents; EPA considers it a probable (B2) carcinogen [1]. The alkylating properties of DDVP may contribute to its carcinogenicity [2].

Children in households using DDVP pest strips or whose pets wear DDVP flea collars — hand-to-mouth contact provides dermal and ingestion exposure [1]. Agricultural workers applying DDVP [2]. Restaurant workers and food service workers who use pest strips in enclosed food storage areas [1].

1. Avoid DDVP pest strips in living areas and any area frequented by children — EPA has restricted household uses significantly [1]. 2. Use non-DDVP flea control products for pets (fipronil spot-ons, oral spinosad, etc.) [2]. 3. If you work in food service and use pest strips, ensure they are only in inaccessible locked areas per current label restrictions [1]. 4. Agricultural workers must use PPE, early re-entry interval compliance, and biological monitoring [2].