Mercury exposure in Montrealers who eat St. Lawrence River sportfish

We assessed levels and determinants of mercury biomarkers among residents of Montreal and surroundings who eat sportfish from the nearby St. Lawrence River. Participants were selected from 1118 adult fishers responding to a 1996 screening questionnaire; the study sample (n=132) overrepresented respondents expected to have the greatest and the least exposure to mercury. Tissue mercury concentrations were associated with sportfish consumption: among participants who ate sportfish at least once weekly, hair geometric mean (GM)=0.82+/-2.54 microg/g and blood mercury GM=3.03+/-2.43 microg/L, compared to hair GM=0.38+/-2.28 microg/g and blood mercury GM=1.44+/-2.23 microg/L for those who ate sportfish less than once weekly. While these levels are somewhat higher than those shown for other Greater Lakes and St. Lawrence River fishers, only one participant surpassed the Canadian recommended population mercury limit of 6 microg/g for hair and 20 microg/L for blood. Consumption of several sportfish species independently explained much of the variation in measured blood mercury; the predatory species pike was the most important in multivariable regression. Coincident consumption of waterfowl, fishing during the longer summer/fall rather than the brief winter season, and fishers' age were independently associated with blood mercury. Serum selenium related neither to the level of fish consumption nor to the participants' blood mercury.