Effect of spatial considerations on PCB cancer risk using sediment accumulation models
- TERRA Inc., Tallahassee, FL (United States)
It is widely recognized that in an aquatic environment, so-called ``superlipophilic`` chemicals like PCBs and chlorinated dioxins preferentially associate with sediments, rather than remain dissolved in the water column. As such, models used to predict bioaccumulation by aquatic organisms should incorporate sediment-associated chemical concentrations, rather than water values. The biota-sediment accumulation factor (BSAF), which is a carbon-normalized ratio of the chemical in the organism to the chemical in the sediments, accounts for this important environmental matrix. However, use of these models requires a consideration of spatial variability not encountered in water-based accumulation models. Monte Carlo analysis was used to quantify the range of PCB associated cancer risks from fish consumption to a hypothetical population based on TOC-normalized PCB sediment data collected from a harbor in the Great Lakes. Use of the arithmetic mean of these data resulted in an associated cancer risk of 8.4E-02. Monte Carlo analysis, varying only the TOC-normalized sediment concentration used to derive fish tissue levels, resulted in risks ranging from 5.8E-05 to 8.0E-00. A sensitivity analysis of these data was performed to determine the relative importance of this variable on calculated cancer risks. These results suggest that estimating cancer risks by the use of BSAF or similar sediment accumulation factors are highly dependent on the spatial variability of sediment PCB values measured at the site. This is an issue which needs to be considered when evaluating the uncertainty of the analysis.
- OSTI ID:
- 40052
- Report Number(s):
- CONF-9410273--
- Country of Publication:
- United States
- Language:
- English
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