Radiocesium in fish from the Savannah River and Steel Creek: Potential food chain exposure to the public

This study examined radiocesium (¹³⁷Cs) levels in fish from the vicinity of the Department of Energy's Savannah River Site (SRS), a former nuclear weapons production facility in South Carolina. Fish from the Savannah River were sampled above (upstream), along, and below (downstream) the SRS, and from Steel Creek, a tributary that runs through the SRS. There was some off-site contamination of ¹³⁷Cs in the Savannah River watershed due to low-level releases from past nuclear production on the SRS. The null hypotheses tested were that there would be no differences in ¹³⁷Cs levels as a function of location along the river, and between species collected from the river and from Steel Creek on the SRS. For six of eight species of fish collected from the Savannah River, there were no differences in ¹³⁷Cs levels in muscle from fish collected above, along, or below the SRS; exceptions were bowfin and shellcracker. Fish collected from Steel Creek had significantly higher levels (by about an order of magnitude) of ¹³⁷Cs in muscle tissue than fish collected in the Savannah River. However, no fish from either Steel Creek or the Savannah River had ¹³⁷Cs levels above the European Economic Community limit for fresh meat of 0.6 Bq/g. Lifetime cancer risk was calculated using the cancer slope factor of 3.2 × 10^-11/pCi, and various fish consumption scenarios reflecting actual data from Savannah River fishermen. Using mean ¹³⁷Cs concentrations and median fish consumption for 70 years for Black males - the group with the highest consumption - the excess lifetime risk associated with the eight species of fish in the Savannah River ranged from 9.0 × 10^-7 to 1.0 × 10^-5. The same calculation for fish from Steel Creek gave risk estimates from 1.4 to 8.0 × 10^-5. The 95% level for consumption by Blacks, however, was about 70 kg/year. Black fishermen consuming that amount of bass from Steel Creek would sustain a lifetime risk of 3.1 ^x 10^-4, whereas the same consumption of Savannah River bass would yield a risk estimate of 1.5 ^x 10^-5.