Mercury in fish from the Upper St. Lawrence River: Temporal and spatial variability and safe consumption rate.

Abstract

Mercury (Hg) levels in fish from the lower Thousand Islands to the Lake St. Francis region of the St. Lawrence River were analyzed over a 20 year period (from 1975 to 1995) by the Ontario Ministry of Natural Resources and the Ontario Ministry of the Environment as part of the Sport Fish Contaminant Monitoring Program. A general linear model was used to extract temporal trends and spatial variability while correcting the data for fish length. The analysis was done on four species of fish: white sucker (Catostomus commersoni (Lacepeede)) an obligate benthivore, yellow perch (Perca flavescens (Mitchill)) an omnivore, and two piscivores, northern pike (Esox lucius Linneaus) and walleye (Stizostedion vitreum (Mitchill)). Fish consumption is the major exposure pathway of Hg to humans. Using current Hg levels, I calculated the safe fish consumption rate. These calculations were based on three reference doses stating the maximum daily exposure of Hg per unit mass of individuals. (Abstract shortened by UMI.)