A preliminary assessment of human health risks due to consumption of fish contaminated by dioxins and furans in the Fraser and Thompson Rivers

Abstract

High levels of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) have been measured in the edible tissues of fish, especially mountain whitefish ( Prosopium williamsonii) exposed to effluent from bleached kraft pulp mills on the Fraser and Thompson Rivers in British Columbia, Canada. In order to assess the health risks 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 on the maximum intake of mountain whitefish proposed in a fish consumption 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 are used to calculate risk using cancer potency factors (CPFs) proposed by various agencies. Implications for at-risk subpopulations are discussed and a revision of the consumption advisory is recommended.