Abstract
Health Canada has been collecting data on Inuit and First Nations' methylmercury (MeHg) levels for 25 years. A national overview has been completed and more focussed analyses have now been initiated. This paper deals with two interdependent analytical components: 1) a longitudinal overview of the two most extensively sampled communities in Canada: Grassy Narrows and Whitedog, the residents of which were exposed to ‘point source’ mercury pollution in the 1970's; 2) fetal and post-natal exposure to mercury in these two communities including an outline of the First Nation MeHg child development pilot project in the two communities. A retrospective analysis of Grassy Narrows and Whitedog shows a decreasing MeHg trend in both communities. In Grassy Narrows the average individual annual peak methylmercury level in blood has decreased significantly, from 23.80 ppb (range 1.50-322.90) in 1976 to 7.5 ppb (1.7-46.7) in 1995 (r=0.65, p<0.001). In Whitedog the average peak has also decreased significantly, from 12.87 ppb (1.50-172.00) in 1976 to 6.1 ppb (1.7-33.3) in 1995 (r=-0.59, p<0.005). However, behind these positive trends is the reality of two communities still suffering the effects of disrupted lifestyles and socio-cultural damage. A number of cord blood samples, maternal blood samples, and samples from women of child-bearing age from these communities have been in the "risk" group (according to the 1990 WHO guidelines). We are therefore now assessing the long term effects of fetal exposure in the communities. Standard clinical examinations in the past failed to prove abnormalities attributable to methylmercury but did not include subtle neuropsychological development tests. Many of the fetally exposed children are now in secondary school. Therefore, we have initiated a pilot project to assess long term effects of methylmercury exposure on the neuropsychological development of these children whose fetal exposure we know. The pilot child development project which was initiated in 1995 in Grass y Narrows and Whitedog, with community support, includes four main components: i) a school records review, looking at attendance, marks, and atypical behaviour; ii) teachers' questionnaires, targeting child behaviour; iii) an in-depth neuropsychological test battery focussing on subtle factors, such as memory, attention, executive functions, perceptual functions and sensory/motor development; and iv) hair sampling, providing current MeHg levels to correlate with results from the previous sampling and findings from the first three components. An overview of progress is given.
Similar content being viewed by others
References
Achenbach, T.M. (1991). Manual for the Teacher's Report Form and 1991 Profile. Burlington, VT: University of Vermont Department of Psychiatry.
Bishop, J.N., and Neary, B.P.: 1976, Mercury levels in Fish from Northwestern Ontario 1970–1975. Ontario Ministry of the Environment, Toronto.
Conners, C.K.: 1969, A teacher rating scale for use in doing studies with children. AM. J. of Psychiatry 126, 884-888.
Erikson, K.: 1994, A New Species of Trouble: Explorations of Disaster, Trauma, and Community. W.W. Norton and Co, New York.
Farant, J.P., Brissette, D., Moncion, L., Bigras, L., and Chartrand, A.: 1981, Improved cold-vapor atomic absorption technique for the microdetermination of total and inorganic mercury in biological samples. J. Anal. Toxicol. 5, 47-51.
Government of Ontario, 1993. Guide to eating Ontario Sport Fish.
McKeown-Eyssen, E.E., and Ruedy, J.: 1983, Prevalence of neurological abnormality in Cree Indians exposed to methylmercury in northern Quebec. Clin. Inves. Med. 6, 161-169.
Myers, G. J., Davidson, W., Cox, C., Shamlaye, C. F., Tanner, M. A., Marsh, D. O., Cernichiari, E., Lapham, L. W., Berlin, M., Clarkson, T. W.: 1995, Summary of the Seychelles Child Development Study on the Relationship of Fetal Methylmercury Exposure to Neurodevelopment. NeuroToxicology 16(4), 711-715.
Phelps, R. W., Clarkson, T.W., Kershaw, T.G., and Wheatley, B.: 1980, Interrelationships of blood and hair mercury concentrations in a North American population exposed to methylmercury. Arch. Environ. Health 35, 161-168.
Rudd, J. W. M., Turner, M. A., Furutani, A., Swick, A. L., and Townsend, B.E.: 1983, The English-Wabigoon River system: I. A synthesis of recent research with a view towards mercury amelioration. Can. J. Fish. Aquat. Sci. 40, 2206-2217.
Shkilnyk, A.M.: 1985, A Poison Stronger than Love: The Destruction of an Ojibwa Community, New Haven, Yale University Press.
Weihe, P., Grandjean, P., Debes, F., White, R.: 1996, Health implications for Faroe Islanders of heavy metals and PCBs from pilot whales. Science of the Total Environment 186, 141-148
Wheatley, B.: 1979, Methylmercury in Canada: Exposure of Indian and Inuit residents to Methylmercury in the Canadian Environment. Department of National Health and Welfare, Medical Services Branch, Ottawa. 200pp
Wheatley, B., Barbeau, A., Clarkson, T. W., and Lapham, L.: 1979, Methylmercury poisoning in Canadian Indians-The elusive diagnosis. Can. J. Neurol. Sci. 6(4), 417-422.
Wheatley, B., Paradis, S.: 1996, Balancing human exposure, risk and reality: Questions raised by the Canadian Aboriginal methylmercury program. NeuroToxicology. 17(1), 241-250.
Wheatley, B., Paradis, S.: 1995, Exposure of Canadian Aboriginal peoples to methymercury. Water, Air and Soil Pollution. 80, 3-11.
Wheatley, M. A.: 1996, The importance of social and cultural effects of mercury on Aboriginal peoples. NeuroToxicology. 17(1), 251-256
WHO: 1990, Environmental Health Criteria 101. Methylmercury. World Health Organisation, Geneva.
WHO: 1976, Environmental Health Criteria I. Mercury. World Health Organisation, Geneva.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Wheatley, B., Paradis, S., Lassonde, M. et al. Exposure Patterns and Long Term Sequelae on Adults and Children in Two Canadian Indigenous Communities Exposed to Methylmercury. Water, Air, & Soil Pollution 97, 63–73 (1997). https://doi.org/10.1023/A:1018311228405
Issue Date:
DOI: https://doi.org/10.1023/A:1018311228405