Environmental contaminants and human health in the Canadian Arctic.

The third Canadian Arctic Human Health Assessment conducted under the Canadian Northern Contaminants Program (NCP), in association with the circumpolar Arctic Monitoring and Assessment Programme (AMAP), addresses concerns about possible adverse health effects in individuals exposed to environmental contaminants through a diet containing country foods. The objectives here are to: 1) provide data on changes in human contaminant concentrations and exposure among Canadian Arctic peoples; 2) identify new contaminants of concern; 3) discuss possible health effects; 4) outline risk communication about contaminants in country food; and 5) identify knowledge gaps for future contaminant research and monitoring. The nutritional and cultural benefits of country foods are substantial; however, some dietary studies suggest declines in the amount of country foods being consumed. Significant declines were found for most contaminants in maternal blood over the last 10 years within all three Arctic regions studied. Inuit continue to have the highest levels of almost all persistent organic pollutants (POPs) and metals among the ethnic groups studied. A greater proportion of people in the East exceed Health Canada's guidelines for PCBs and mercury, although the proportion of mothers exceeding these guidelines has decreased since the previous assessment. Further monitoring and research are required to assess trends and health effects of emerging contaminants. Infant development studies have shown possible subtle effects of prenatal exposure to heavy metals and some POPs on immune system function and neurodevelopment. New data suggest important beneficial effects on brain development for Inuit infants from some country food nutrients. The most successful risk communication processes balance the risks and benefits of a diet of country food through input from a variety of regional experts and the community, to incorporate the many socio-cultural and economic factors to arrive at a risk management decision that will be the most beneficial in Arctic communities.

Human health implications of environmental contaminants in Arctic Canada: A review.

The objectives of this paper are to: assess the impact of exposure to current levels of environmental contaminants in the Canadian Arctic on human health; identify the data and knowledge gaps that need to be filled by future human health research and monitoring; examine how these issues have changed since our first assessment [Van Oostdam, J., Gilman, A., Dewailly, E., Usher, P., Wheatley, B., Kuhnlein, H. et al., 1999. Human health implications of environmental contaminants in Arctic Canada: a review. Sci Total Environ 230, 1-82]. The primary exposure pathway for contaminants for various organochlorines (OCs) and toxic metals is through the traditional northern diet. Exposures tend to be higher in the eastern than the western Canadian Arctic. In recent dietary surveys among five Inuit regions, mean intakes by 20- to 40-year-old adults in Baffin, Kivalliq and Inuvialuit communities exceeded the provisional tolerable daily intakes (pTDIs) for the OCs, chlordane and toxaphene. The most recent findings in NWT and Nunavut indicate that almost half of the blood samples from Inuit mothers exceeded the level of concern value of 5 microg/L for PCBs, but none exceeded the action level of 100 microg/L. For Dene/Métis and Caucasians of the Northwest Territories exposure to OCs are mostly below this level of concern. Based on the exceedances of the pTDI and of various blood guidelines, mercury and to a lesser extent lead (from the use of lead shot in hunting game) are also concerns among Arctic peoples. The developing foetus is likely to be more sensitive to the effects of OCs and metals than adults, and is the age groups of greatest risk in the Arctic. Studies of infant development in Nunavik have linked deficits in immune function, an increase in childhood respiratory infections and birth weight to prenatal exposure to OCs. Balancing the risks and benefits of a diet of country foods is very difficult. The nutritional benefits of country food and its contribution to the total diet are substantial. Country food contributes significantly more protein, iron and zinc to the diets of consumers than southern/market foods. The increase in obesity, diabetes and cardiovascular disease has been linked to a shift away from a country food diet and a less active lifestyle. These foods are an integral component of good health among Aboriginal peoples. The social, cultural, spiritual, nutritional and economic benefits of these foods must be considered in concert with the risks of exposure to environmental contaminants through their exposure. Consequently, the contamination of country food raises problems which go far beyond the usual confines of public health and cannot be resolved simply by risk-based health advisories or food substitutions alone. All decisions should involve the community and consider many aspects of socio-cultural stability to arrive at a decision that will be the most protective and least detrimental to the communities.

Arctic indigenous peoples experience the nutrition transition with changing dietary patterns and obesity.

Indigenous Peoples globally are part of the nutrition transition. They may be among the most extreme for the extent of dietary change experienced in the last few decades. In this paper, we report survey data from 44 representative communities from 3 large cultural areas of the Canadian Arctic: the Yukon First Nations, Dene/Métis, and Inuit communities. Dietary change was represented in 2 ways: 1) considering the current proportion of traditional food (TF) in contrast to the precontact period (100% TF); and 2) the amount of TF consumed by older vs. younger generations. Total diet, TF, and BMI data from adults were investigated. On days when TF was consumed, there was significantly less (P < 0.01) fat, carbohydrate, and sugar in the diet, and more protein, vitamin A, vitamin D, vitamin E, riboflavin, vitamin B-6, iron, zinc, copper, magnesium, manganese, phosphorus, potassium, and selenium. Vitamin C and folate, provided mainly by fortified food, and fiber were higher (P < 0.01) on days without TF for Inuit. Only 10-36% of energy was derived from TF; adults > 40 y old consistently consumed more (P < 0.05) TF than those younger. Overall obesity (BMI > or = 30 kg/m(2)) of Arctic adults exceeded all-Canadian rates. Measures to improve nutrient-dense market food (MF) availability and use are called for, as are ways to maintain or increase TF use.

Fish-seafood consumption, obesity, and risk of type 2 diabetes: an ecological study.

OBJECTIVES: There is substantial evidence that type 2 diabetes increases with the degree and duration of obesity. This study was conducted to examine the association, at the international level, between fish and seafood consumption and the prevalence of type 2 diabetes, taking into account the prevalence of obesity. METHODS: An ecological study of 41 countries in five continents with different socio-demographic characteristics and sanitary conditions was carried out. Data on the prevalence of diabetes and obesity as well as food balance sheets were collected from websites. Correlations between the variables studied were followed by an exploration of their interaction. RESULTS: After adjustment for total energy intake, there was a significant correlation (rho=0.81, P<0.0001) between the prevalence of type 2 diabetes in the 20- to 44- and 45- to 64-year age groups. Type 2 diabetes in the 45- to 64-year age group was about 5 times higher than in the 20- to 44-year age group. Obesity was positively associated with type 2 diabetes in both age groups (rho=0.39; P=0.012 and rho=0.48; P=0.002 in the 20- to 44- and 45- to 64-year age groups, respectively). An interaction effect was found between diabetes, obesity and total fish and seafood consumption. In countries with low fish and seafood consumption, the prevalence of type 2 diabetes increased significantly with obesity (0.8 +/- 0.3% vs. 2.5 +/- 1.8%; P=0.002 and 3.3 +/- 2.6% vs. 11.0 +/- 3.9%; P<0.0001 for the 20- to 44- and 45- to 64-year age groups, respectively). In countries with a greater prevalence of obesity, there was evidence of significantly reduced type 2 diabetes with high fish and seafood consumption (2.5 +/- 1.8% vs. 0.9 +/- 0.7%; P=0.007 and 11.0 +/- 3.9% vs. 6.2 +/- 4.1%; P=0.041 for the 20- to 44- and 45- to 64-year age groups, respectively). CONCLUSION: The results of this study suggest that high fish and seafood intake may reduce the risk of type 2 diabetes in populations with a high prevalence of obesity.

Traditional food systems research with Canadian Indigenous Peoples.

Traditional food systems research with Canadian Indigenous Peoples has revealed many aspects of benefits and risks of the use of this food. Traditions based in hunting, fishing and gathering contain a great variety of species of wildlife plants and animals that provide rich cultural and nutritional benefits. Dietary change for Indigenous Peoples in Canada has resulted in the use of traditional food to provide usually less than 30% of total dietary energy; however this portion of the total diet contributes significantly more of essential nutrients. It also results in exposure to organochlorine and heavy metal contaminants that exceed the tolerable intake levels for some areas. A successful research and education intervention program with one British Columbia community demonstrated that increasing traditional food use can improve health status for vitamin A, iron and folic acid. It is concluded that traditional food systems are rich with potential for research and public health education intervention programs for Indigenous Peoples.

Association between vitamin A status and lung function level in children aged 6--9 years in Wukro wereda, Northern Ethiopia.

BACKGROUND: In developing countries, studies using morbidity recalls to evaluate the benefits of vitamin A on respiratory health in children under 6 years of age have been inconclusive. This relationship has not been examined in older children. Spirometric measurements, an objective means of assessing respiratory health, require the subject's collaboration and have been successfully used in children over 6 years of age. This report describes a cross-sectional analysis of the relationship between lung function and vitamin A status in an area endemic to vitamin A deficiency. METHODS: The data on which this report is based were gathered prior to the implementation of a prospective trial of the effect of vitamin A supplementation on lung function level in Northern Ethiopia. Vitamin A status was assessed by the Modified Relative Dose Response (MRDR) method and lung function assessed by spirometry in 702 rural children aged 6--9 years. Demographic, personal health, household, environmental and socioeconomic data were gathered by questionnaire. RESULTS: In children with low vitamin A reserve, the unadjusted forced expiratory volume in one second (FEV(1)) was 48.8 ml (P = 0.006) lower than in those with adequate reserve. This difference was 23.1 ml (P = 0.04) when adjusted for age, gender and height and 14.1 ml (P = 0.20) when adjusted for children's demographic, general health, lung function and household-related characteristics. CONCLUSION: Although these findings suggest that vitamin A plays a relatively minor role in determining FEV(1) level, interpretation is limited by the cross-sectional design. Further clarification of its role requires a trial of vitamin A supplementation.

Prevalence of vitamin A deficiency in children aged 6-9 years in Wukro, northern Ethiopia.

OBJECTIVE: To determine the prevalence of vitamin A deficiency in children aged 6-9 years in northern Ethiopia. METHODS: A cross-sectional study was carried out and the data were analysed for 824 (61.5%) of 1339 eligible children for whom there was complete information on biochemical vitamin A status, dietary vitamin A intake, ocular examination for xerophthalmia, and anthropometry. FINDINGS: The prevalence of xerophthalmia was 5.8%; serum retinol levels were below 0.35 mumol/l and between 0.35 and 0.70 mumol/l in 8.4% and 51.1% of the children respectively. The liver vitamin A reserve (modified relative dose response ratio > or = 0.06) was low in 41.0% of the children. CONCLUSION: The high prevalence of severe vitamin A deficiency in children aged 6-9 years indicates the need to reevaluate the practice of targeting vitamin A supplementation programmes on children under 6 years of age in areas where vitamin A deficiency is endemic.

Mercury in the traditional diet of indigenous peoples in Canada.

Traditional food of indigenous people in Canada, particularly fish and marine mammal meat, has mercury (Hg) concentrations exceeding the Canadian consumption guideline level of 0.5 microg/g. Health effects 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.

Dietary intake and body mass index of adults in 2 Ojibwe communities.

OBJECTIVE: To describe and compare dietary intake and prevalence of overweight in a sample of adults in 2 Ojibwe communities in Mille Lacs, Minn, and Lac Courte Oreilles, Wis. DESIGN: Cross-sectional survey based on interviews that included a 24-hour recall, food frequency questionnaire, and a sociocultural questionnaire. SUBJECTS/SETTING: One hundred four adult Band (tribe) members were selected randomly from current housing lists; pregnant and lactating women were excluded. STATISTICAL ANALYSES PERFORMED: Nonparametric Wilcoxon rank sum tests were used to determine differences in absolute nutrient intakes where normality could not be assumed. Two-tailed t tests were conducted to test for differences between nutrient densities. A significance level of alpha = .05 was used; procedurewise adjustments were made using the Bonferroni method when adjusting for multiple comparisons. RESULTS: The importance of the traditional food system was evident: at least 50% of respondents engaged in hunting and fishing practices. Prevalence of overweight was 47%. Mean nutrient intakes were below the Recommended Dietary Allowance for women for vitamin A, folate, calcium, iron, and zinc and for men for vitamin A and calcium, despite energy intakes that met the Recommended Dietary Allowance. Nutrient densities were lower than those in the third National Health and Nutrition Examination Survey for women for carbohydrate, vitamin C, folate, calcium, and dietary fiber and for men for folate and dietary fiber. Fat contributed 37% (for men) and 40% (for women) of energy intake. APPLICATIONS/CONCLUSIONS: Areas of focus for culturally relevant education programs (eg, promotion of traditional foods that provide nutrients of low intake status and low-fat traditional food preparation methods) and research needs are suggested to reduce risks for nutrition-related chronic disease among Native Americans.

Consumption of freshwater fish in Kahnawake: risks and benefits.

Kahnawake is a Mohawk community located on the south shore of the Saint Lawrence River near Montreal. A comprehensive study was conducted in 1996-1997 to address the local concern regarding health risks of contaminant exposure associated with freshwater fish consumption. Forty-two participants, including most of the identified active fishermen (n=33), were interviewed. Walleye, perch, bullhead, and smallmouth bass were the species most consumed. Average daily intake of locally caught fish was 23 g/day. Nutrient and contaminant levels of locally collected fish were analyzed. Fish were good sources of protein, polyunsaturated fatty acids (particularly omega-3 fatty acids), calcium, zinc, and iron. Levels of cadmium, lead, arsenic, polychlorinated biphenyls (PCBs), and other chlorinated pesticides were at least 10 times lower than the guideline levels. Mercury levels of some predatory fish exceeded the guideline of 0.5 microgram/g. Average daily intakes of all contaminants were below the guideline levels by a factor of 10 except for mercury. Average mercury intake rate was about one-third that of the guideline level (200 micrograms/week). Contrary to residents' perception, Kahnawake fish were not particularly contaminated. In view of the nutritional as well as cultural benefits, fishing and fish consumption may be promoted.

Risk assessment of cadmium exposure in Fort Resolution, Northwest Territories, Canada.

The aim of this study is to investigate the cadmium (Cd) exposure level from traditional food in Fort Resolution, Northwest Territories. We used 24-h dietary recalls and traditional food use frequency to obtain information on traditional food consumption, and analysed cadmium concentrations in traditional food. We also estimated total cadmium intake via market and traditional food, and cigarette smoking. Traditional food accounted for only 10% of the dietary energy. About 30 species of wildlife and plants were used. The most important foods in the community were moose, caribou, and whitefish. The range of cadmium concentrations measured was 0 to 1869 micrograms/g wet weight, with the lowest found in cranberry, and the highest in moose kidney. Cadmium concentrations in traditional food groups were comparable with those of Canadian market food. Highest levels of cadmium were found in the liver and kidney of caribou and moose. Cadmium intakes from traditional food estimated by dietary recall ranged from 0.01 to 1713 micrograms/g/day/person. Average cadmium intakes for women and men from traditional food were estimated to be 9% and 6% respectively, of the Provisional Tolerable Weekly Intake (PTWI, 400-500 micrograms) established by the World Health Organization. The average cadmium inhaled from cigarette smoking was 2.31 +/- 1.00 micrograms/day/person. There was no difference between the total cadmium intakes of smokers and nonsmokers. The total cadmium intake via market and traditional food and cigarette smoking was 136.6 micrograms/ week, which was lower than the PTWI. However, about 20% of the population may consume caribou and moose organ more frequently than the others. The potential health effects on this sub-population needs further clarification.

Population exposure to radioactivity from consumption of caribou among the Dene/Métis of Denendeh (western Northwest Territories, Canada).

There has been long-standing concern with exposure to radioactivity through the consumption of caribou, particularly in indigenous populations in the western Northwest Territories, Canada, who are traditionally high consumers. We conducted a dietary survey in this region in 1994 to estimate population exposure levels. Dietary information was collected from 1012 individuals in sixteen communities (1012 days of 24-hour dietary recalls, 1012 food frequency questionnaires) and radionuclide levels in caribou flesh, liver and kidneys were measured. Monte Carlo statistical methods were employed to integrate these data sets and estimate the distribution of radiation exposure for people in five regions (Gwich'in, Sahtú, Dogrib, Deh-Cho, South Slave). The exposure levels were highest in the South Slave region and in older males (40+ years), and lowest in the Gwich'in region and in younger females (20-40 years). Median exposure level ranged from 0.95 to 5.31 mSv per year (mean of medians = 2.96 mSv/y). In each group the 95th percentile of exposure was 2-3 times greater than the median. These exposure levels are comparable to exposure levels in Alaskan Eskimos and Marshall Island residents, and are much higher than European or American urban populations. Caribou meat is a very nutritious food. We conclude that, although there is some radiation exposure from consuming caribou, the associated health risks are low and are outweighed by the physical, social and cultural benefits derived from hunting and eating caribou.

Dietary exposure to chemical contaminants from traditional food among adult Dene/Métis in the western Northwest Territories, Canada.

Environmental contaminants such as organochlorines and heavy metals have been reported to bioaccumulate in Arctic and subarctic wildlife. The Indigenous Peoples in northern and Arctic Canada rely on local wildlife as an important food source, and it is thus hypothesized that they may have high intakes of these contaminants. Herein, an assessment of dietary exposure to selected organochlorines and heavy metals for Indigenous Peoples of the western Northwest Territories (NWT) is presented. Dietary data were collected from 1012 adults with 24-h recalls in 16 communities in the western NWT (Denendeh). A comprehensive survey of the literature, as well as in-house analysis, formed the basis of a large traditional food-contaminant database. By combining the dietary and contaminant data, dietary exposure to 11 chemical contaminants was calculated. Dietary exposure to chemical contaminants in Denendeh is generally low and there is little, if any, associated health risk. However there are specific contaminants in certain communities for which exposure on a single day approaches the tolerable daily intake levels. These situations are detailed and monitoring needs are described.

Sources of bias in estimates of calcium and vitamin A intakes of indigenous peoples in the Northwest Territories, Canada.

Calcium and vitamin A have consistently been reported as nutrients at risk among northern indigenous peoples in Canada. Using a data set recently collected in the Sahtú region of Denendeh, Northwest Territories, potential sources of bias and their effect on estimates of dietary intake are investigated. Calcium and vitamin A intakes appear to be underestimated to differing extents and for differing reasons specific to each nutrient. Underestimation of calcium intake may affect a large portion of the dietary records and is most likely due to insufficient probing for methods of food preparation during dietary interviews. Underestimation of vitamin A intake appears to affect a smaller proportion of the food records and be related to the difficulty of recording the occurrence of rare and seasonal events. In both cases, more precise nutrient composition data are needed to reflect nutrient content of traditional food as consumed.

Benefits of traditional food in Dene/Métis communities.

Data collected in 16 Dene/Métis communities are used to illustrate the many nutritional, economic, and sociocultural benefits associated with the harvest and consumption of traditional food by indigenous peoples. These include exceptional nutrient composition, absence of industrial processing that changes quality and taste properties, taste preference, reasonable cost compared to market food, quality of the time spent on the land, increased physical activity, sharing of the harvest within the community, opportunity to practice spirituality, and encouragement for children to discover the natural environment. The importance of traditional food to the health of individuals and communities can be directly related to the nutritional value of the food itself, the physical activity associated with its procurement, and its role in mediating positive health determinants such as self-efficacy and locus of control.

Decreasing traditional food use affects diet quality for adult Dene/Métis in 16 communities of the Canadian Northwest Territories.

We assessed diets in 16 Dene/Métis communities in the Canadian Arctic. We described nutrient intakes and identified nutrients at risk among adult Dene/Métis, evaluated the influence of traditional food on diet quality, and examined the direction of dietary change by comparing intergenerational and between-community differences in dietary intake. Diet varied according to sex, age and community. Nutrients of possibly inadequate intake (irrespective of subject sex, age or community) included calcium, vitamin A and folic acid. Dietary fiber intake was also of concern. Traditional food (animals and plants harvested from the local environment) was consumed on 65. 4% of interview days; on those days intakes of iron, zinc and potassium were higher (P < 0.05) and those of sodium, fat, saturated fat and sucrose were lower (P < 0.05) than on days when market food only was consumed. In this population, the shift away from traditional food towards a diet composed exclusively of market food was characterized by an increase (P < 0.05) in absolute energy intake and an increase (P < 0.01) in the relative contributions of carbohydrate (particularly sucrose), fat and saturated fat. This pattern of change calls for initiatives to document the current health status of this population and to prevent potential negative health consequences of dietary change.

Evaluation of the population distribution of dietary contaminant exposure in an Arctic population using Monte Carlo statistics.

Organochlorines and heavy metals have bioaccumulated in Arctic wildlife, which is an important food source for the Inuit. In this study, we have developed a statistical model to describe the population distribution of contaminant exposure and the usual intake of the high-end contaminant consumers. Monte Carlo methods are used to account for variations due to seasonal dietary pattern and contaminant concentrations. Distribution of the dietary intake of the contaminants of most concern-mercury, polychlorinated biphenyls (PCBs), chlordane, and toxaphenes-are described. Over 50% of the residents had dietary exposure levels exceeding the tolerable daily intake or provisional tolerable daily intake for Hg, toxaphene, and chlordane (83, 91, and 71% for men and 73, 85, and 56% for women, respectively). The high-end consumers (i.e. the 95th centile) have intake levels 6 times higher than the provisional tolerable weekly intake of Hg, and over 20 times the tolerable daily intake of chlordane and toxaphene. Assessment of health risks of the relative high contaminant exposure in this community must also consider the nutritional, economical, cultural, and social importance of these traditional foods. A comprehensive risk management scheme has yet to be developed.