MERCURY IN FISH FROM CHRISTINA LAKE, ALBERTA, CANADA-RISK ASSESSMENT

Abstract

Mercury is a concern in aquatic ecosystems due to its bioaccumulation and its developmental toxicity to the humans, especially young children. There is existing mercury-related fish consumption advisory on brook trout in Chrystina Lake issued in the early 1990s. In order to review the fish consumption advisory, a project of mercury levels in brook trout was carried out between 1999 and 2001. The field collection was carried out between August and September 1999 and in August 2001. Sixteen brook trout and white sucker were collected in 1999, and fifteen brook trout and white sucker were collected in 2001. Total mercury and methylmercury were analyzed in fillets of fish. The mean concentrations of total mercury in fillets of brook trout were 122 μg/kg (wet weight) in 1999 and 197 μg/kg (wet weight) in 2001. The mean concentrations of total mercury in fillets of white sucker was 188 μg/kg (wet weight) in 1999 and 2001. Health Canada proposed the guidelines and the total daily intake for consumption of mercury-contained fish. In the absence of the intake estimations, the guideline is 500 μg/kg (0.5 ppm) Hg for commercial fish. This guideline is used as a general screening tools. The guideline for subsistence fresh water fishing populations is 200 μg/kg (0.2 ppm) Hg. The concentrations of total mercury in brook trout and white sucker from Chrystina Lake were less than 200 μg/kg. Health Canada proposed that the total daily intake (TDI) of mercury for women of childbearing age and children is 0.2 μg Hg/Kg bw/d, and the 0.47 μg Hg/Kg bw/d for the general population. Estimated daily intake and exposure ratios based on TDIs from Health Canada are summarized in Table:Exposure ratios were greater than one for the high intake group of women of childbearing age and children. Hence, women of childbearing age and children should not consume a large quantity of brook trout caught from Chrystina Lake.