Developing Parameters for Uncommon Exposures

Common exposure scenarios form the basis for exposure assessments included in human health risk assessments. The quantitative parameters that are used to calculate the receptor's dose associated with these common exposure scenarios are readily available. When humans have uncommon exposures, these often are excluded from the dose calculations because of the lack of parameters or parameters are estimated, which can increase the uncertainty in calculated dose. This study evaluates a third option of performing laboratory experiments to estimate parameters for uncommon exposures. Two exposures, the handling and hand-washing of contaminated work clothes and the drinking of water with sufficient free-phase hydrocarbons to form a visible sheen, were simulated in a laboratory. Parameters were developed for each exposure such that doses could be calculated. Parameters developed include a mass of oily contaminants on skin after washing contaminated clothes and the mass of a visible oily sheen on an aqueous surface. These results demonstrate that developing parameters for uncommon exposure scenarios is a practical alternative to eliminating or estimating exposures and these experiments can be done in compliance with human subject protocols.