EXPOSURE OF ABORIGINALS IN BRITISH-COLUMBIA TO METHYLMERCURY IN FRESH-WATER FISH - A COMPARISON TO REFERENCE DOSES AND ESTIMATED THRESHOLDS

We have analyzed the methylmercury exposures of native women consuming fish from a reservoir and two lakes in British Columbia. Probability density functions representing methylmercury dose were generated using reasonable distributions for exposure parameters. Sensitivity analyse s were performed to assess the impact of alternative parameter values on the exposure estimates. The effect of ignoring variability and unce rtainty in exposure was also assessed. Calculated mean daily doses of methylmercury for the target populations were compared to the estimate d average dose for the general population. We also determined the perc entages of the native women populations with exposures exceeding curre nt guidance values as well as published thresholds for neurological ef fects. The analysis demonstrates the importance of better characterizi ng the low dose effects of methylmercury, as the predicted doses fall in the range of recommended maximum daily doses but well below the hig her estimates of the effect threshold.