ABSTRACT
The objectives of this work are to demonstrate methods for the collection and incorporation of contact-specific surface area measurements in dermal exposure assessments and illustrate the potential difference in resulting dermal and non-dietary ingestion estimates using this type of surface area data. Continuing the work of Stanford's Exposure Research Group, categorical surface area data contained in children's sequential microlevel activity patterns were converted into quantitative coordinates, which in turn provided a foundation to map data on the skin surface. Programs were constructed to establish an accounting system of spatial coordinates, governed by categorical surface area data, to map exposure estimates or activity statistics on the skin. An illustrative example is provided that estimates the spatial variability of chlorpyrifos on the palm of a hand using contact-specific surface area data. Results show a maximum value of 14.6 ng on the fingertips and no chemical exposure along the edges of the fingers and in the center of the palm. The methodologies presented could result in more realistic estimates of concentration gradients across the skin, better representations of dermal exposure due to multiple contacts, improved approximations of nondietary ingestion, and enhanced models of dermal dose.