Movement and Deposition of Two Organophosphorus Pesticides within a Residence after Interior and Exterior Applications

Abstract

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 IMPLICATIONSThe Food Quality Protection Act (FQPA) of 1996 mandates that when setting a food tolerance level for a pesticide, the EPA must aggregate exposure information from all potential sources, including residues from other nondietary, nonoccupational uses of the pesticide (i.e., residential indoor/outdoor uses). FQPA further mandates that potential risks to infants and small children be specifically addressed. It is important, therefore, to understand the routes by which small children are exposed to pesticides used in and around the home. This study was designed to determine how semi-volatile pesticides are redistributed after residential use and the degree to which small children may be exposed to them as a result. Data presented here show that when using current exposure models, indoor exposure to airborne organophosphorus pesticides outweighs that from dust ingestion, but suggests that mouthing of skin residues may contribute to higher nondietary exposures.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 µg/kg/day for diazinon applied indoors and 0.05 µg/kg/day for chlorpyrifos applied to the outside perimeter of the house. While ingestion of carpet dust at the rate of 100 µg/day would have added a maximum of only ~0.01 µg/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 µg/kg/day. These estimates are below the U.S. Environmental Protection Agency (EPA) reference dose for chlorpyrifos, but exceed those for diazinon.

Determinants of temporal variability in NHEXAS-Maryland environmental concentrations, exposures, and biomarkers

“…A doorway between the living quarters and the garage (GARAGE), a common location for pesticide storage, was associated with higher indoor levels. The positive association with number of hours spent outside at home (OUTHOME) suggests pesticides may have been tracked in from the lawn (Lewis et al, 2001) despite the negative association for outdoor pesticide use in the past 6 months (OUTPEST); there was no significant correlation (P ¼ 0.46, Spearman) between OUT-HOME and OUTPEST. The effect of central air conditioning (A/C, yes or no) during the monitoring period may be confounded by more frequent use of both residential and agricultural pesticides in the spring and summer months (MacIntosh et al, 1999b).…”

Frequency of mouthing behavior in young children

“…To illustrate the use of these equations to estimate the potential indirect ingestion exposure from a pesticide via hand -to -mouth activity, we apply it to monitoring data obtained for diazinon by Lewis et al ( 2001 ). The microenvironment is the living room of a residential dwelling where a 24 -month -old female child ( weight = 13.5 kg) spends 4 h in the microenvironment ( e.t = LR.4 h ).…”

Pesticide Concentrations in Vacuum Dust from Farm Homes: Variation between Planting and Nonplanting Seasons

“…Pesticides can be transported into homes soon after spraying [3] and family members may be exposed through home contamination even though they did not participate in farming activities [4]. Homes near farm operations where pesticides are used may be contaminated via air, shoes and clothing, or pets [5].…”