Recommendations for the derivation and use of biota-sediment bioaccumulation models for carcinogenic polycyclic aromatic hydrocarbons.

Carcinogenic polycyclic aromatic hydrocarbons (cPAHs) are important sediment contaminants that can pose health risks to people who eat shellfish from contaminated sites. Biota-sediment accumulation factors (BSAFs) are quotients of colocated lipid-normalized tissue concentrations and organic carbon (OC)-normalized sediment concentrations, whereas biota-sediment accumulation regressions (BSARs) are models describing the relationships between these tissue and sediment concentrations. BSAR/Fs (BSARs and/or BSAFs) are commonly used to back-calculate sediment preliminary remediation goals (PRGs) from target tissue concentrations; the PRGs are then used to set target action levels (i.e., sediment concentrations above which remedial actions will be prescribed). The cPAH BSAR/Fs reported across sites and species are highly variable due to both site- and species-specific differences and inconsistent BSAR/F calculation methods and assumptions. We reviewed past studies, identified best practices for developing BSAR/Fs, and compiled publicly available colocated tissue and sediment data for 7 cPAHs from 13 sites across the United States. Of the 249 unique cPAH data sets compiled for various species, only 17 yielded acceptable BSAR/Fs, 16 of which were for clams. The influence of BSAR/Fs on sediment remedial action decisions and costs can be disproportionate to the quality of the statistical models from which they are derived. Therefore, it is important to establish and follow best practices for deriving BSAR/Fs and for deciding whether and how BSAR/Fs should be used. Based on our review and analysis, we highlight the advantages of relying on BSARs and propose a consistent method for deriving and judging the reliability of these relationships. We also offer guidance for evaluating the ramifications of BSAR uncertainty on remedial decision making at contaminated sediment sites, and we discuss alternative ways to make risk management decisions in the absence of a reliable site-specific BSAR. Integr Environ Assess Manag 2017;13:1060-1071. © 2017 SETAC.