Animal Studies in Support of a Risk Assessment of Polycyclic Organic Matter (POM) in Fine Particulates. L. S. Goldstein, Electric Power Research Institute, 3403 Hillview Avenue, Palo Alto, CA 94303
Are data from studies of either individual signature polycyclic aromatic hydrocarbons (PAH, e.g. benzo(a)pyrene) or organic extracts of complex mixtures of PAH adequate for risk assessment? Our research suggests uncertainties for both hazard identification and dose-response. Ingested benzo(a)pyrene is a presystemic (point of contact) tumorigen whereas ingested complex mixtures of tumorgenic PAH containing benzo(a)pyrene are systemic tumorigens. Different PAH having different tumorigenic potencies have different absorption affinities on particles; biological systems are not as effective as organic extractions in desorbing these constituents. The availability of those components known or suspected to cause tumors will have significant impact on the dose component of a risk assessment. Thus our data suggest that a quantitative risk assessment for POM should be based on data of tumor outcomes for the POM-containing fine particles rather than on PAH surrogates or organic extracts.