Comparison of Carcinogenic Risk for PAHs in Soils at a Superfund Site and PAHs in Shampoo Containing Coal Tar. J. S. Smith, Jr., PTI Environmental Services, Inc. 460 Totten Pond Road, Waltham, MA 02154; D. Bencivengo, Pacific Analytical, Inc., 6349 Paseo Del Lago, Carlsbad, CA 92009; and J. S. Smith, Trillium, Inc., 28 Grace’s Drive, Coatesville, PA 19320
Polycyclic aromatic hydrocarbons (PAHs) are a group of more than 100 chemicals formed in the incomplete combustion of organic substances. The Environmental Protection Agency (EPA) regulates several of these PAHs based on their relative potency to produce carcinogenic effects in laboratory animals. As a consequence, EPA determined direct contact with soils at a Superfund site to be a potential human health hazard. EPA’s Record of Decision (ROD) for this site reports a maximum PAH soil concentration of 88.5 parts per million (ppm) and suggests that exposure to this level poses an unacceptable carcinogenic risk to humans. Based on current land use and other exposure parameters described in the ROD, EPA requires cleanup of site soils to 30 ppm corresponding to a 10-5 carcinogenic risk level. In order to place this carcinogenic risk into perspective, we compared updated carcinogenic risk estimates associated with dermal exposure and incidental ingestion of Superfund site soils to carcinogenic risk estimates for PAHs in shampoo using EPA guidance regarding dermal exposure assessment. Although exposure to PAHs from contaminated soils is fundamentally different from exposure to PAHs in shampoos, our findings suggest that reasonable use of shampoo containing coal tar presents orders of magnitude greater carcinogenic risk than does exposure to PAH contaminated Superfund site soils. These findings suggest that cleanup levels for PAHs at Superfund site soils could be much higher without adding significant carcinogenic risk to exposed humans.