Refining ConsExpo Evaporation and Human Exposure Calculations for REACH

Abstract

ABSTRACT REACH (Registration, Evaluation, and Authorization of CHemicals) and other regulations require assessing potential exposure to substances in consumer products in order to determine if the potential risk from the product use is acceptable. In order to assess inhalation exposure due to evaporation of the volatile substance in a consumer product the vapor concentration must be determined. The vapor concentration may be measured or estimated using mathematical modeling. Both options have many advantages and disadvantages but because of the large number of substances and products to be evaluated, modeling is usually the first choice. The primary objective was to present an approach based on sound science to refine an exposure analysis by refining the mass transfer coefficient in the ConsExpo evaporation calculations for use in the subsequent inhalation exposure calculations. This study recommends use of the Sparks et al. (1996) method for estimating the mass transfer coefficient for indoor evaporation. Three case studies demonstrated the Sparks method provided a better agreement of the predicted vapor concentrations to experimental results than the default mass transfer methods. A second objective was to critically evaluate the two ConsExpo default methods used to estimate the mass transfer coefficient and several limitations were identified.