Mercury levels in the Cree population of James Bay, Quebec, from 1988 to 1993/94

Abstract

BACKGROUND: High levels of mercury in the Cree population of James Bay, Que., have been a cause of concern for several years. This study examines changes in mercury levels within the Cree population between 1988 and 1993/94 and identifies potential determinants of high mercury levels. METHODS: Data on mercury levels among the Cree were obtained through a surveillance program undertaken by the Cree Board of Health and Social Services of James Bay. In 1988 and again in 1993/94 surveys were carried out in all 9 Cree communities of northern Quebec. Hair samples were obtained and analysed for mercury content. Analyses were carried out to determine the proportion of people who had mercury levels in excess of established norms. Changes in mercury levels between 1988 and 1993/94 and determinants of high levels were estimated by means of regression methods. RESULTS: The proportion of the Cree population with mercury levels in excess of 15.0 mg/kg declined from 14.2% in 1988 to 2.7% in 1993/94. Wide variations in mercury levels were observed between communities: 0.6% and 8.3% of the Eastmain and Whapmagoostui communities respectively had mercury levels of 15.0 mg/kg or greater in 1993/94. Logistic regression analyses showed that significantly higher levels of mercury were independently associated with male sex, increasing age and trapper status. There was a correlation between the mercury level of the head of the household and that of the spouse. INTERPRETATION: Mercury levels in the Cree of James Bay have decreased in the recent past. Nevertheless, this decrease in mercury levels may not be permanent and does not necessarily imply that the issue is definitively resolved.