A PRELIMINARY ASSESSMENT OF HUMAN HEALTH RISKS DUE TO CONSUMPTION OF FISH CONTAMINATED BY DIOXINS AND FURANS IN THE FRASER AND THOMPSON RIVERS

High levels of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlor inated dibenzofurans (PCDFs) have been measured in the edible tissues of fish, especially mountain whitefish (Prosopium williamsonii) expose d to effluent from bleached kraft pulp mills on the Fraser and Thompso n Rivers in British Columbia, Canada. In order to assess the health ri sks to consumers of locally caught fish, lifetime average daily doses (LADDs) of PCDD/F congeners, expressed in toxic equivalent quantities of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), were calculated based o n the maximum intake of mountain whitefish proposed in a fish consumpt ion advisory issued by the B.C. Ministry of Health. LADDs are compared to the TDI of 10 pg/kg/day proposed by the Government of Canada and a re used to calculate risk using cancer potency factors (CPFs) proposed by various agencies. Implications for at-risk subpopulations are disc ussed and a revision of the consumption advisory is recommended.