Estimating fish consumption rates for Ontario Amerindians

The routine assessment of human exposure to contaminants requires that exposure via consumption of freshwater fish be considered because many chemicals persist and/or bioaccumulate in fish. Estimates of fish consumption rate were determined for Ontario Amerindians from data on the concentration of mercury in the hair of 4,327 Amerindians residing in 58 reserves across the province, combined with data on mercury concentrations in three commonly consumed species of fish collected from lakes surrounding these reserves. Estimated rates of fish consumption were found to differ between sexes, with males consuming a geometric mean of 19 g of fish per day, while females were estimated to consume a geometric mean of 14 g/day. Fish consumption rate was found to increase with increasing latitude, a surrogate measure of community isolation, and to increase with age. Seasonal variation was also noted, with fish consumption rates being highest during summer months and lowest in winter. These data may provide regulatory agencies with a more statistically representative basis upon which to establish assumptions concerning fish consumption rates for risk assessment purposes. Factors such as the location of the exposed population, age and sex of exposed individuals, and time of year in which an assessment is being conducted, should also be considered as specific situations require.