Movement and deposition of two organophosphorus pesticides within a residence after interior and exterior applications

Post-application temporal and spatial distributions of two organophosphorus pesticides, diazinon (O,O-diethyl O-[6-methyl-2-(1-methylethyl)-4-pyrimidinyl] phosphorothioate, CAS No. 333-41-5) and chlorpyrifos [O,O-diethyl-O-(2-isopropyl-6-methyl-4-pyrimidinyl) phosphorothioate, CAS No. 2921-88-2], were monitored after homeowner applications for indoor and outdoor insect control. Samples of indoor air, vacuumable carpet dust, carpet dislodgeable residues, deposits on bare floors, table tops and dinnerware, surrogate food, and residues on children's hands and toys were taken before and up to 12 days after treatments in the family room, kitchen, and child's bedroom. Results from the study demonstrate the nature and magnitude of translocation of pesticides from the areas of application to surfaces accessible for human contact and permit comparisons of potential exposures via respiration and dermal contact/oral ingestion. Potential indoor inhalation exposures were estimated to be as high as 0.5 mug/kg/day for diazinon applied indoors and 0.05 mug/kg/day for chlorpyrifos applied to the outside perimeter of the house. While ingestion of carpet dust at the rate of 100 mug/day would have added a maximum of only similar to0.01 mug/kg/day to the daily dose, residues found on the children's hands suggest that repeated mouthing could have contributed as much as 1-1.5 mug/kg/day. These estimates are below the U.S. Environmental Protection Agency (EPA) reference dose for chlorpyrifos, but exceed those for diazinon.