Biota--sediment accumulation factors for polychlorinated biphenyls, dibenzo-p-dioxins, and dibenzofurans in southern Lake Michigan lake trout (Salvelinus namaycush).

A set of high-quality, age-specific biota-sediment accumulation factors (BSAFs) for polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs) have been determined from concentrations measured with high-resolution gas chromatography/high-resolution mass spectrometry, by use of the 13C isotopic dilution technique, in lake trout and surficial (0-2 cm) sediment samples from southern Lake Michigan. BSAFs ranged from <0.1 to 18 for PCBs and from <0.001 to 0.32 for PCDDs and PCDFs detected in the fish. PCBs with zero or one chlorine in an ortho position had smaller BSAFs than other PCBs. PCDDs and PCDFs with chlorines at the 2,3,7,8-positions had larger BSAFs than most other PCDDs and PCDFs. The fidelity of the relative bioaccumulation potential data between independent lake trout samples, within and among age classes, suggests that differences in slight rates of net metabolism in the food chain are important and contribute to the apparent differences in BSAFs, not only for PCDDs and PCDFs but also possibly for some PCBs. A complicating factor for non-ortho- and mono-ortho-PCBs is the uncertain contribution of enhanced affinity for black carbon (and possibly volatility) acting in concert with metabolism to reduce measured BSAFs for lake trout. On the basis of the association between chemicals with apparent slight rates of metabolism and measured dioxin-like toxicity, several PCDFs with similar measured BSAFs but unknown toxicity may be candidates for toxicity testing.