CURRENT RISK ASSESSMENT APPROACHES TO ADDRESS PETROLEUM HYDROCARBON MIXTURES IN SOILS

Products that exist as complex chemical mixtures, such as petroleum pr oducts, are used widely in commerce, and accidental releases of these products into the environment have led to thousands of contaminated si tes nationwide. Developing sound estimates of potential health risks p osed by these sites is challenging because of the composition of these products, their behavior in the environment, and the paucity of toxic ological information available for many of the component compounds. In developing risk-based cleanup goals for petroleum products and other complex commercial mixtures, the simplest approach is to assume that t he entire mixture is comprised of the most toxic constituent, particul arly when standards are unavailable for each of the components of the mixture. This approach often results in excessively conservative regul atory goals; thus, methods are needed which more accurately reflect th e actual composition and aggregate toxicity of the mixture. Three appr oaches for the development of risk-based soil cleanup goals for petrol eum hydrocarbon mixtures are identified and illustrated using mineral spirits as an example. For the examples presented, estimates of the pr oportions of components in mineral spirits were based on virgin, unuse d product; however, detailed component analysis of weathered samples m ay permit the calculation of more precise, site-specific cleanup goals .