Development of an indirect sampler for the estimation of dermal exposure to pesticides in housedus

The goal of this doctoral project was the development, laboratory validation and field implementation of an indirect microenvironmental press sampler for dermal exposure estimation as a result of hand contact on a dust laden surface.;Characterization of seasonal variation in particle size fractions of household dusts deposited onto indoor surfaces in the home indicated that dust mass was greater during the summer than during the winter. The total number of particles deposited, however, was greater during the winter than during the summer. The increase in winter time particle number was caused by greater numbers of particles with an equivalent spherical diameter <2.5 mum. Since over 99% of the particles on indoor surfaces were smaller than 50 mum any indirect sampling technique for dermal exposure estimation should have collection efficiencies similar to the hand for particles smaller than 50 mum.;In controlled laboratory collection efficiency tests the Edwards-Lioy (EL) sampler collected 35 +/- 5% atrazine, 31 +/- 3% diazinon, 32 +/- 5% malathion and 18 +/- 3% chlorpyrifos from housedust laden surfaces. Pesticide collection efficiencies measured on the investigator's hand were 42 +/- 7%, 29 +/- 8%, 43 +/- 8% and 21 +/- 5%, respectively. The collection efficiencies of the two sampling techniques were highly correlated for atrazine, diazinon, and chlorpyrifos (correlation coefficient = 0.840, 0.815 and 0.706), but not for malathion (correlation coefficient = 0.086). Octanol/water partitioning coefficients for each pesticide indicated that the polarity of the compound was indicative of which variable (skin hydration or sebum) influenced collection efficiency of the skin.;Field validation of the EL sampler was performed as part of both the National Human Exposure Assessment Survey (NHEXAS)-Pesticide Module and the Minnesota Children's Pesticide Study. Median chlorpyrifos levels collected by the EL sampler were 20% of the average Values collected by the modified Lioy-Weisel-Wainman (LWW) wipe sampler. This was in close agreement with laboratory collection tests. The EL sampler collected similar atrazine and chlorpyrifos concentrations on both carpets and smooth surfaces (r2 = 0.81; p = 0.00001). Chlorpyrifos concentrations measured by the EL sampler showed no correlation with handrinse levels. Dust sampling methods were not good indicators of internal chlorpyrifos levels.