Dermal transfer of chlorpyrifos residues from residential surfaces: Comparison of hand press, hand drag, wipe, and polyurethane foam roller measurements after broadcast and aerosol pesticide applications

Indoor residential pesticide applications present the potential for human e xposures, particularly for small children. Personal contact with target and nontarget surfaces can result in transfer of pesticides to the skin, but t he magnitude of such transfer is uncertain. This research compared surface sampling techniques [wipe and polyurethane foam (PUF) roller] with the remo val ability of human skin following broadcast and total aerosol release app lications of Dursban (Dow Elanco, Midland, MI), a residential formulation c ontaining the insecticide chlorpyrifos. Hands were washed immediately after surface contact, following a protocol that included a laboratory-generated adjustment factor to account for incomplete removal of chlorpyrifos from s kin. Chlorpyrifos transfer was similar for hand press and hand drag techniq ues, averaging approximately 1-6 ng/cm(2) of carpet contacted. These amount s represented < 1% of the amount of chlorpyrifos deposited on the surfaces 3.5 hr earlier. Chlorpyrifos transfer from carpet to skin was 23-24 times l ower than for wipe sampling and 33-36 times lower than for PUF roller sampl ing (p = 0.0007 and p = 0.0006 for broadcast and aerosol applications, resp ectively). Hand press sampling removed approximately 4.5 times less chlorpy rifos from nontarget furniture surfaces (12 ng/cm(2)) than did wipe samplin g (56 ng/cm(2); p = 0.009). Chlorpyrifos residues on carpet were substantia lly higher after broadcast applications than after aerosol applications, bu t residues on such nontarget surfaces as furniture were substantially highe r for the aerosol application. This study indicates that human skin removes substantially less residue from carpets and furniture than either conventi onal wipe or PUF roller sampling methods following residential pest control applications of chlorpyrifos. Although this paper focuses on quantifying r esidue transfer from surface to skin using different surface sampling techn iques, no attempt is made to quantify the amount of chlorpyrifos residue th at is subsequently absorbed.