Are exposure and ecological risks of PAHs underestimated at petroleum contaminated sites?

Ecological risk assessments conducted under the provisions of the Resource Conservation and Recovery Act (RCRA) and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) typically rely on either U.S. Environmental Protection (USEPA) priority pollutant or Appendix IX analyte lists. These methods quantify only a limited subset of the polycyclic aromatic hydrocarbons (PAHs) and heterocyclic aromatics found in oil and oil process wastes. Advances in analytical chemistry and petroleum fingerprinting techniques now show that the alkylated PAHs found in petroleum are more abundant and more persistent than the non-alkylated PAHs quantified by the traditional analytical methods applied in ecological risk assessments. We performed a screening level evaluation using case studies of PAH contamination from petroleum releases in a take receiving refinery wastes and intertidal sediments exposed to spilled oil to assess the magnitude of underestimation of risks to ben thic invertebrates and wildlife. Risks were assessed using a probabilistic approach and demonstrated that traditional analytical chemistry approaches applied at RCRA and CERCLA sites will underestimate exposure and risks of petrogenic PAHs contaminating aquatic systems. This analysis also shows that the numerical correction factor that has been proposed to account for 'unmeasured' alkylated PAHs can also result in a substantial underestimation of PAH risks from petroleum releases.