Bull. Environ. Contam. Toxicol. (1991) 46:276-283 ~Environmental ~Contamination ~and Toxicology Accumulation Factors for Eleven Polychlorinated Biphenyl Congeners Steven P. Ferraro, Henry Lee II, Lawrence M. Smith, Robert J. Ozretich, and David T. Specht U.S. Environmental Protection Agency, Pacific Ecosystems Branch, Mark O. Hatfield Marine Science Center, Newport, Oregon 97365, USA Aceording to the fugacity approaeh (Mackay 1979), pollutant uptake by an organism is determined by the chemical fugacity differential between the organism and its environment. The Accumulation Factor [AF = (concentration of pollutant in animal tissue, C t (ng/g dry wt)/animal lipid (%/100))/(concentration of pollutant in sediment, C s (ng/g dry wt)/sediment total organic carbon, TOC (%/100))] is a simple, fugacity-based model which bas been shown to be useful for predicting the bioaccumulation potential of hydrophobic neutral organic compounds in sediment- dwelling animals (Rubinstein et al. 1987; McElroy and Means 1988; Clarke et al. 1988; Ferraro et al. 1990). The theoretical basis for the AF model is discussed in Mackay (1979), Mackay and Paterson (1981, 1982), McFarland (1984), McFarland and Clarke (1986), and Lake e__~t al. (1987). The model assumes chemical equilibrium or steady-state in the animals and the sediments to which they are exposed, no chemical transformation or phase transfer resistance, and chemical partitioning primarily between the organic pool in the sediment and the lipid pool in the animal. If AFs are constant for a given chemical (or group of chemicals), AFs can be used to predict C t (or an upper bound for Ct) given Cs, TOC and % animal lipids by ratio estimation (Snedecor and Cochran 1967). The applied value of AFs is as a cost-effective, environmentally protective screening tool for evaluating sediment quality (McFarland 1984; Lake et al. 1987; Rubinstein et al. 1987; Ferraro e_ital. 1990). Ferraro et al. (1990) tested the constancy of AFs for ten hydrophobie neutral organic compounds by exposing clams (Macoma nasuta) in the laboratory for 28 days to six field-collected sediments varying widely in Cs, TOC, and other chemical and physical characteristics. Sediment and tissue samples from that study were archived and latter analyzed for II polychlorinated biphenyl (PCB) congeners. In this paper we report mean and maximum AFs (AFmax) for II PCB congeners and test the constancy of the AFs across 5 sediments (treatments) by congener and across the ii congeners by treatment. Send reprint requests to S.P. Ferraro at the above address. 276