Carcinogenic polycyclic aromatic hydrocarbons: an analysis of screening values, guidelines, and standards in the...

Risk-based, background, and laboratory quantitation limit-derived standards for carcinogenic polycyclic aromatic hydrocarbons (cPAHs) in residential and nonresidential soils vary across the northeast region of the United States. The magnitude and extent of this variation, however, have not been systematically studied. This article examines the technical basis and methodology used by eight northeastern states in the development of risk-based screening values, guidelines, and standards for cPAHs in soils. Exposure pathways, human receptors, algorithms, and input variables used by each state in the calculation of acceptable human health risks are identified and reviewed within the context of environmental policy and regulatory impacts. Emphasis is placed on a comparative analysis of multipathway exposures (incidental ingestion, dermal contact, and particulate inhalation) and key science-policy decisions that have led to the promulgation and adoption of different exposure criteria for cPAHs in the Northeast. More than 425 data points and 20 distinct exposure factors across eight state programs, 18 age subgroups, six activity scenarios, and three exposure pathways were systematically evaluated. Risk-based values for one state varied either above or below risk-based, background or laboratory quantitation limit-derived standards of another state for the same cPAH and receptor. Standards for cPAHs in soils were found to differ significantly across the northeast region--in some cases, by one or two orders of magnitude. While interstate differences can be expected to persist, future changes in federal guidance could mean a shift in risk drivers, compliance status, or calculated cumulative risks for individual properties impacted by PAH releases.