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Mercury in the traditional diet of indigenous peoples in Canada
Environmental Pollution 110 (2000) 1±2
www.elsevier.com/locate/envpol
Commentary
Mercury in the traditional diet of indigenous peoples in Canada Hing Man Chan a,b,*, Olivier Receveur a,b a
Centre for Indigenous Peoples' Nutrition and Environment (CINE), Macdonald Campus of McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, Canada H9X 3V9 b School of Dietetics and Human Nutrition, Macdonald Campus of McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, Canada, H9X 3V9 Received 17 December 1999; accepted 17 January 2000
``Capsule'': Marine mammals were identi®ed as the greatest source of dietary mercury.
Abstract Traditional food of indigenous people in Canada, particularly ®sh and marine mammal meat, has mercury (Hg) concentrations exceeding the Canadian consumption guideline level of 0.5 mg/g. Health eects of Hg in traditional food are, therefore, a concern. We conducted contaminant exposure assessments in 28 indigenous communities in Canada. Hg exposure was greatest among communities with high use of marine mammals as food. Exposure among other communities was variable. Recent adoption of a lower intake guideline for women of reproductive age and by Health Canada may decrease the use of traditional food, and could result in other health problems, such as increased risk of diabetes and cardiovascular disease. # 2000 Elsevier Science Ltd. All rights reserved. Keywords: Traditional food; Indigenous people; Canada; Contamination; Mercury
Long-term exposure to mercury (Hg) can permanently damage the brain, kidneys, and developing fetus (ASTDR, 1989). Hg concentrations in ®sh in eastern North America frequently exceed recommended maximum concentrations for human consumption (OMOE/OMNR, 1988). Indigenous peoples in Canada are among the most exposed populations to Hg because ®sh, and marine mammals for the Inuit, are important components of their traditional diet (Kuhnelin and Receveur, 1996). In the last 6 years, under the Arctic Environmental Strategy administered by the Department of Indian and Northern Aairs, there has been an extensive eort to monitor the level of contaminants, including Hg, in ®sh and wildlife collected from dierent regions in northern and arctic Canada (Jensen et al., 1997). We conducted an extensive literature review on levels of environmental contaminants in northern Canada (Chan, 1998) including the ranges of Hg in 79 species of marine mammals, terrestrial mammals, birds, ®sh and plants. High levels of Hg are found in ®sh from northern Quebec because of methylation of Hg in reservoirs. Forty percent of ®sh exceeded the * Corresponding author. Tel.: +1-514-398-75-44; fax: +1-514-39810-20. E-mail address: [email protected] (Hing Man Chan).
guideline level of 0.5 m/g total Hg. In other regions of northern Canada only 2% of ®sh exceeded the guideline level. Thirty-two percent of mammal meat samples and 64% of terrestrial mammal samples exceeded 0.5 mg/g. In the last 5 years, we also conducted contaminant exposure assessments in one Inuit community on Ban Island, 16 Dene/MeÂtis communities in Denendeh [Northwest Territories (NWT)], 10 Yukon First Nations communities, and one Mohawk community in Quebec. In the Inuit community, over 50% of residents had dietary exposure levels exceeding the Provisional Tolerable Daily Intake (PTDI) for Hg (83% for men, 73% for women) (Chan et al. 1997). High-end consumers (i.e. 95th percentile) had intake levels six times higher than the PTDI. The problem was less serious in the Dene/MeÂtis communities, where less than 1% of the population had usual intakes exceeding the PTDI. Nevertheless, we recommended continued monitoring given the large amount of ®sh consumed in that region (Berti et al., 1998). In the Yukon, 99% of people consumed less than the level considered tolerable for Hg. In Quebec, we conducted a study among 42 ®shermen in Kahnawake, a Mohawk community located on the south shore of the Saint Lawrence River near Montreal (Chan et al., 1999). The average daily intake of locally caught ®sh was only 23 g/day. Even though Hg
0269-7491/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved. PII: S0269-7491(00)00061-0
2
H.M. Chan, O. Receveur / Environmental Pollution 110 (2000) 1±2
levels of some predatory ®sh exceeded the guideline of 0.5 g/g, average Hg intake was only about one-third of the PTDI. The ®shermen reported a steady decline of ®sh consumption over the last 10 years. Fear of contaminants was listed as one of the factors. From 1970 to 1995, the Medical Services Branch of Health Canada conducted Hg analyses of hair and blood samples obtained from 38,571 residents of 514 native communities across Canada (Wheatley, 1994). A declining trend in blood Hg concentrations was found among First Nations communities south of 60 N (Wheatley and Paradis, 1998). However, it is not certain that this is because of falling Hg levels in the traditional diet or because less traditional food is being eaten by the people. In the NWT, approximately 20% of Dene and 57% of Inuit tested had blood levels exceeding the guideline of 20 mg/L (Wheatley and Paradis, 1995). After reviewing new epidemiological data (Davidson et al., 1998; Grandjean et al., 1998), Health Canada proposed a provisional no observable adverse eect level (NOAEL) of 10 mg/L Hg in maternal hair (Feeley and Lo, 1998). Converting to an equivalent daily intake from food and using a ®ve-fold uncertainty factor to account for inter-individual variability, the PTDI for women of reproductive age and infants was revised to 0.2 mg/kg body weight/day (Feeley and Lo, 1998). When news of this new guideline reaches indigenous communities, avoidance of traditional food may increase, particularly among Inuit populations. The shift away from traditional diets may result in a rise in obesity, diabetes, and cardiovascular disease among indigenous peoples in the USA and Canada (Young, 1993; Young et al., 1993). Increased saturated fat, sucrose, and alcohol in diets has led to higher incidences of gall bladder disease, tooth decay, alcoholism and its complications, and foetal alcohol syndrome. Poor diet quality has also been associated with higher incidences of anemia, otitis media, a variety of infections, and to some kinds of cancer (Kuhnelin and Receveur 1996). Moreover, the diet change may lead to a loss of culture and identity as the entire socioeconomic system is disrupted (Usher et al., 1995). Among the Dene/MeÂtis and most other First Nations communities, the real threat from Hg exposure may be low. Unfortunately, the perception of high health risk is pervasive. Information on what food is safe and what food is not safe needs to be better communicated and an on-going monitoring program for contaminants needs to be implemented so that traditional food will remain safe for future generations. Harvesting and using traditional food should be promoted. The risk management issue is more complicated among Inuit communities. A comprehensive risk management program involving health professionals, community representatives, government regulators and other stakeholders is urgently needed.
The communities must balance the health risks of contaminant exposure versus the cultural and nutritional bene®ts of the use of traditional food systems. The role of the scienti®c community is to provide information that will allow people to make an informed decision. References ATSDR (Agency for Toxic Substances and Disease Registry), 1989. Toxicological pro®le for mercury. ATSDR, Public Health Service, Department of Health and Human Services, Atlanta, GA. Berti, P.R., Receveur, O., Chan, H.M., Kuhnlein, H.V., 1998. Dietary exposure to chemical contaminants from traditional food among adult Dene/MeÂtis in the western Northwest Territories, Canada. Environmental Research 76, 131±142. Chan, H.M., 1998. A database for environmental contaminants in traditional foods in northern and arctic Canada: development and applications. Food Addit. Contam. 15, 127±134. Chan, H.M., Berti, P., Receveur, O., Kuhnlein, H.V., 1997. Evaluation of the population distribution of dietary contaminant intakes in an Arctic population using bootstrap statistics. Environmental Health Perspectives 105, 316±321. Chan, H.M., Trifonopoulos, M., Ing, A., Receveur, O., Johnson, E., 1999. Consumption of freshwater ®sh in kahnawake: risks and bene®ts. Environmental Research 80, S213±S222. Davidson, P.W., Myers, G.J., Cox, C., Axtell, C., Shamlaye, C., Sloane-Reeves, J. et al., 1998. Eects of prenatal and postnatal methylmercury exposure from ®sh consumption on neurodevelopment: outcomes at 66 months of age in the Seychelles Child Development Study. JAMA 280, 701±707. Feeley, M.M., Lo, M.T., 1998. Risk assessment for mercury in Health Canada Ð development of the Provisional Tolerable Daily Intake (pTDI) value. In: Proceedings of the Conference on Mercury in Eastern Canada and the Northeast States. 21±23 September 1998, Fredericton, New Bunswick. Grandjean, P., Weihe, P., White, R.F., Debes, F., 1998. Cognitive performance of children prenatally exposed to ``safe'' levels of methylmercury. Environmental Research 77, 165±172. Jensen, J., Adare K., Shearer R. (Eds.), 1997. Canadian Arctic Contaminants Assessment Report. Indian and Northern Aairs Canada, Ottawa. Kuhnelin, H.V., Receveur, O., 1996. Dietary change and traditional food systems of indigenous peoples. Annu. Rev. Nutr. 16, 417±442. OMOE/OMNR, 1988. Guide to Eating Ontario Sport®sh. Ontario Ministry of the Environment/Ontario Ministry of Natural Resources, Toronto, Ontario, Canada. Usher, P.J., Baikie, M., Demmer, M., Nakashima, D., Stevenson, M.G., Stiles, M. 1995. Communicating about contaminants in country food: the experience in aboriginal communities. Inuit Tapirisat of Canada, Ottawa. Wheatley, B., 1994. Exposure of Canadian aboriginal peoples to methylmercury. Environ. Sci. 3, 33±40. Wheatley, B., Paradis, S., 1995. Exposure of Canadian aboriginal peoples to methylmercury. Water Air Soil Pollution 80, 3±11. Wheatley, B., Paradis, S., 1998. Northern Exposure: further analysis of the results of the Canadian Aboriginal methylmercury program. Int. J. Cirumpolar Health 57 (Suppl. 1), 586±590. Young, T.K., 1993. Diabetes mellitus among native americans in Canada and United States: an epidemiological review. Am. J. Hum. Biol. 5, 399±413. Young, T.K., Moat, M.E.K., O'Neil, J.D., 1993. Cardiovascular diseases in a Canadian Arctic population. Am. J. Public Health 83, 881±887.
www.elsevier.com/locate/envpol
Commentary
Mercury in the traditional diet of indigenous peoples in Canada Hing Man Chan a,b,*, Olivier Receveur a,b a
Centre for Indigenous Peoples' Nutrition and Environment (CINE), Macdonald Campus of McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, Canada H9X 3V9 b School of Dietetics and Human Nutrition, Macdonald Campus of McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, Canada, H9X 3V9 Received 17 December 1999; accepted 17 January 2000
``Capsule'': Marine mammals were identi®ed as the greatest source of dietary mercury.
Abstract Traditional food of indigenous people in Canada, particularly ®sh and marine mammal meat, has mercury (Hg) concentrations exceeding the Canadian consumption guideline level of 0.5 mg/g. Health eects of Hg in traditional food are, therefore, a concern. We conducted contaminant exposure assessments in 28 indigenous communities in Canada. Hg exposure was greatest among communities with high use of marine mammals as food. Exposure among other communities was variable. Recent adoption of a lower intake guideline for women of reproductive age and by Health Canada may decrease the use of traditional food, and could result in other health problems, such as increased risk of diabetes and cardiovascular disease. # 2000 Elsevier Science Ltd. All rights reserved. Keywords: Traditional food; Indigenous people; Canada; Contamination; Mercury
Long-term exposure to mercury (Hg) can permanently damage the brain, kidneys, and developing fetus (ASTDR, 1989). Hg concentrations in ®sh in eastern North America frequently exceed recommended maximum concentrations for human consumption (OMOE/OMNR, 1988). Indigenous peoples in Canada are among the most exposed populations to Hg because ®sh, and marine mammals for the Inuit, are important components of their traditional diet (Kuhnelin and Receveur, 1996). In the last 6 years, under the Arctic Environmental Strategy administered by the Department of Indian and Northern Aairs, there has been an extensive eort to monitor the level of contaminants, including Hg, in ®sh and wildlife collected from dierent regions in northern and arctic Canada (Jensen et al., 1997). We conducted an extensive literature review on levels of environmental contaminants in northern Canada (Chan, 1998) including the ranges of Hg in 79 species of marine mammals, terrestrial mammals, birds, ®sh and plants. High levels of Hg are found in ®sh from northern Quebec because of methylation of Hg in reservoirs. Forty percent of ®sh exceeded the * Corresponding author. Tel.: +1-514-398-75-44; fax: +1-514-39810-20. E-mail address: [email protected] (Hing Man Chan).
guideline level of 0.5 m/g total Hg. In other regions of northern Canada only 2% of ®sh exceeded the guideline level. Thirty-two percent of mammal meat samples and 64% of terrestrial mammal samples exceeded 0.5 mg/g. In the last 5 years, we also conducted contaminant exposure assessments in one Inuit community on Ban Island, 16 Dene/MeÂtis communities in Denendeh [Northwest Territories (NWT)], 10 Yukon First Nations communities, and one Mohawk community in Quebec. In the Inuit community, over 50% of residents had dietary exposure levels exceeding the Provisional Tolerable Daily Intake (PTDI) for Hg (83% for men, 73% for women) (Chan et al. 1997). High-end consumers (i.e. 95th percentile) had intake levels six times higher than the PTDI. The problem was less serious in the Dene/MeÂtis communities, where less than 1% of the population had usual intakes exceeding the PTDI. Nevertheless, we recommended continued monitoring given the large amount of ®sh consumed in that region (Berti et al., 1998). In the Yukon, 99% of people consumed less than the level considered tolerable for Hg. In Quebec, we conducted a study among 42 ®shermen in Kahnawake, a Mohawk community located on the south shore of the Saint Lawrence River near Montreal (Chan et al., 1999). The average daily intake of locally caught ®sh was only 23 g/day. Even though Hg
0269-7491/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved. PII: S0269-7491(00)00061-0
2
H.M. Chan, O. Receveur / Environmental Pollution 110 (2000) 1±2
levels of some predatory ®sh exceeded the guideline of 0.5 g/g, average Hg intake was only about one-third of the PTDI. The ®shermen reported a steady decline of ®sh consumption over the last 10 years. Fear of contaminants was listed as one of the factors. From 1970 to 1995, the Medical Services Branch of Health Canada conducted Hg analyses of hair and blood samples obtained from 38,571 residents of 514 native communities across Canada (Wheatley, 1994). A declining trend in blood Hg concentrations was found among First Nations communities south of 60 N (Wheatley and Paradis, 1998). However, it is not certain that this is because of falling Hg levels in the traditional diet or because less traditional food is being eaten by the people. In the NWT, approximately 20% of Dene and 57% of Inuit tested had blood levels exceeding the guideline of 20 mg/L (Wheatley and Paradis, 1995). After reviewing new epidemiological data (Davidson et al., 1998; Grandjean et al., 1998), Health Canada proposed a provisional no observable adverse eect level (NOAEL) of 10 mg/L Hg in maternal hair (Feeley and Lo, 1998). Converting to an equivalent daily intake from food and using a ®ve-fold uncertainty factor to account for inter-individual variability, the PTDI for women of reproductive age and infants was revised to 0.2 mg/kg body weight/day (Feeley and Lo, 1998). When news of this new guideline reaches indigenous communities, avoidance of traditional food may increase, particularly among Inuit populations. The shift away from traditional diets may result in a rise in obesity, diabetes, and cardiovascular disease among indigenous peoples in the USA and Canada (Young, 1993; Young et al., 1993). Increased saturated fat, sucrose, and alcohol in diets has led to higher incidences of gall bladder disease, tooth decay, alcoholism and its complications, and foetal alcohol syndrome. Poor diet quality has also been associated with higher incidences of anemia, otitis media, a variety of infections, and to some kinds of cancer (Kuhnelin and Receveur 1996). Moreover, the diet change may lead to a loss of culture and identity as the entire socioeconomic system is disrupted (Usher et al., 1995). Among the Dene/MeÂtis and most other First Nations communities, the real threat from Hg exposure may be low. Unfortunately, the perception of high health risk is pervasive. Information on what food is safe and what food is not safe needs to be better communicated and an on-going monitoring program for contaminants needs to be implemented so that traditional food will remain safe for future generations. Harvesting and using traditional food should be promoted. The risk management issue is more complicated among Inuit communities. A comprehensive risk management program involving health professionals, community representatives, government regulators and other stakeholders is urgently needed.
The communities must balance the health risks of contaminant exposure versus the cultural and nutritional bene®ts of the use of traditional food systems. The role of the scienti®c community is to provide information that will allow people to make an informed decision. References ATSDR (Agency for Toxic Substances and Disease Registry), 1989. Toxicological pro®le for mercury. ATSDR, Public Health Service, Department of Health and Human Services, Atlanta, GA. Berti, P.R., Receveur, O., Chan, H.M., Kuhnlein, H.V., 1998. Dietary exposure to chemical contaminants from traditional food among adult Dene/MeÂtis in the western Northwest Territories, Canada. Environmental Research 76, 131±142. Chan, H.M., 1998. A database for environmental contaminants in traditional foods in northern and arctic Canada: development and applications. Food Addit. Contam. 15, 127±134. Chan, H.M., Berti, P., Receveur, O., Kuhnlein, H.V., 1997. Evaluation of the population distribution of dietary contaminant intakes in an Arctic population using bootstrap statistics. Environmental Health Perspectives 105, 316±321. Chan, H.M., Trifonopoulos, M., Ing, A., Receveur, O., Johnson, E., 1999. Consumption of freshwater ®sh in kahnawake: risks and bene®ts. Environmental Research 80, S213±S222. Davidson, P.W., Myers, G.J., Cox, C., Axtell, C., Shamlaye, C., Sloane-Reeves, J. et al., 1998. Eects of prenatal and postnatal methylmercury exposure from ®sh consumption on neurodevelopment: outcomes at 66 months of age in the Seychelles Child Development Study. JAMA 280, 701±707. Feeley, M.M., Lo, M.T., 1998. Risk assessment for mercury in Health Canada Ð development of the Provisional Tolerable Daily Intake (pTDI) value. In: Proceedings of the Conference on Mercury in Eastern Canada and the Northeast States. 21±23 September 1998, Fredericton, New Bunswick. Grandjean, P., Weihe, P., White, R.F., Debes, F., 1998. Cognitive performance of children prenatally exposed to ``safe'' levels of methylmercury. Environmental Research 77, 165±172. Jensen, J., Adare K., Shearer R. (Eds.), 1997. Canadian Arctic Contaminants Assessment Report. Indian and Northern Aairs Canada, Ottawa. Kuhnelin, H.V., Receveur, O., 1996. Dietary change and traditional food systems of indigenous peoples. Annu. Rev. Nutr. 16, 417±442. OMOE/OMNR, 1988. Guide to Eating Ontario Sport®sh. Ontario Ministry of the Environment/Ontario Ministry of Natural Resources, Toronto, Ontario, Canada. Usher, P.J., Baikie, M., Demmer, M., Nakashima, D., Stevenson, M.G., Stiles, M. 1995. Communicating about contaminants in country food: the experience in aboriginal communities. Inuit Tapirisat of Canada, Ottawa. Wheatley, B., 1994. Exposure of Canadian aboriginal peoples to methylmercury. Environ. Sci. 3, 33±40. Wheatley, B., Paradis, S., 1995. Exposure of Canadian aboriginal peoples to methylmercury. Water Air Soil Pollution 80, 3±11. Wheatley, B., Paradis, S., 1998. Northern Exposure: further analysis of the results of the Canadian Aboriginal methylmercury program. Int. J. Cirumpolar Health 57 (Suppl. 1), 586±590. Young, T.K., 1993. Diabetes mellitus among native americans in Canada and United States: an epidemiological review. Am. J. Hum. Biol. 5, 399±413. Young, T.K., Moat, M.E.K., O'Neil, J.D., 1993. Cardiovascular diseases in a Canadian Arctic population. Am. J. Public Health 83, 881±887.