In June 1997 The Arctic Environmental Strategy (AES) -Northern Contaminants Program (NCP) issued a report entitled Canadian Arctic Contaminants Assessment Report (CACAR), a culmination of six years of scientific research and more than 100 studies.1 It is the most comprehensive collection and report of data on environmental contamination in the Canadian Arctic to date. Accompanying the report, the NCP also published a less technical volume entitled Highlights of the Canadian Arctic Contaminants Assessment Report: a community reference manual, which was aimed at community health and environment representatives in the North.2 This article summarizes the CA CAR documents and provides an overview of the key elements of the report.
Contaminants in the Arctic:
Reasons for Concern
The Arctic was once considered a pristine environment; however, during the last 20 years, scientists have found significant levels of industrial and agricultural chemicals in its ecosystem and in the people who live there. The contaminants include organochlorines [OCs, also referred to as persistent organic pollutants (POPs)], heavy metals, and radionuclides, which originate principally from distant industrial and agricultural regions of the world. There are some local sources such as mines and radar station sites, but their contribution to contaminant loading is far less than that of those originating through long-range transport (table 1). Persistent contaminants have been detected throughout Arctic ecosystemsair, surface seawater, suspended sediments, snow,3 fish, marine mammals, seabirds,4 and terrestrial plants and animals.5
Several of the contaminants of concern in the Arctic are no longer used in Canada and their use has, in many cases, been banned or restricted in most of the developed world. Because they continue to be used in many developing nations, however, reduction of contamination in the Canadian Arctic can be achieved only through global action.
The presence of environmental contaminates in the Arctic is especially important because of the specificity of this ecosystem. Many of these chemicals condense in cold environments and the Arctic is such a "cold trap," typified by long-lived, fat-rich organisms that accumulate and concentrate contaminants to the upper levels of the food chain. Unexpectedly high levels of organic contaminants and metals have been detected in some Arctic fish, seals, and whales that are important parts of the diets and nutrition of many Arctic residents. Chemical contamination of these traditional foods provides a critical path of contaminant transfer to human consumers, particularly northern Aboriginal peoples.6 Although the message currently given to northerners is to continue their consumption of country foods, detection of elevated levels of contaminants has generated human health advisories to decrease consumption of or eliminate from the diet certain tissues and species of fish and wildlife in specific areas of Yukon and the Northwest Territories.7
The Northern Contaminants Program was designed to determine the types and levels of contaminants in the Arctic, the extent to which people are exposed, the effects of such exposure, and the impacts of strategies to reduce or eliminate contamination and human exposure to contaminants. The CACAR documents the current state of contamination in the Canadian Arctic environment, including the status and trends of contaminant levels, and compares findings in the Canadian North with findings from other areas of the world.
A multidisciplinary approach was adopted and managed by the Department of Indian Affairs and Northern Development (DIAND) in partnership with five Aboriginal organizationsInuit Tapirisat of Canada (ITC); Inuit Circumpolar Conference (ICC); Métis Nation-NWT; Council of Yukon First Nations (CYFN); and the Dene Nationand several federal and territorial government departments and agencies including the Department of the Environment, Fisheries and Oceans, Health Canada, and GNWT Health (figure 1). Some of the research was carried out by government scientists; some in universities across the country; and some by the NCP's Aboriginal partners. Inuit Tapirisat of Canada prepared a report entitled "Researcher Guidelines for Planning Communications and Community Participation," which outlines a series of requirements for community participation and communication through all stages of research from proposal development to the reporting of results. These guidelines were endorsed by the NCP science managers in 1994 and issued as part of the application package for all research proposals to the NCP starting in 1994/95.
The NCP's findings are of concern because of the potential human health implications for many northern native peoples arising from their dependence on traditionally harvested foods and their position as high food-chain consumers. As many as 91% of native households in the Northwest Territories consume traditionally harvested meat and fish, and 22% have reported that all their meat and fish are obtained through harvest activities. When traditionally harvested foods are reduced or eliminated as a food source, there are serious nutritional, socio-economic, and cultural impacts on northern Aboriginal peoples.
What Did We Learn?
Contaminants: Sources, Pathways, and Fate
Human activities in industrialized and agricultural regions in both developed and developing countries are the main sources of contaminants in the Canadian Arctic. Accurate and complete information is required on the release of these pollutants into the environment to develop effective international strategies to reduce the input of contaminants to the Arctic.
It is difficult to determine the proportion of anthropogenic versus natural sources of heavy metals to the total contaminant loading to the Arctic. From an economic perspective, the extraction of base and precious metals has, for many years, been important to the North, where nickel, copper, lead, zinc, silver, and gold are all currently mined. The by-products of the mining industry may result in elevated levels of trace metals and other contaminants within a localized area and may threaten human health and the local environment. In contrast, localized, naturally elevated concentrations of heavy metals in areas undisturbed by human activities may result in elevated concentrations in resident biota but have little consequence for the health of the biota. For example, natural mercury sources occur regionally in parts of the western Arctic, whereas natural cadmium sources are more widespread across the Canadian Arctic.
Detectable levels of radioactivity result mostly from the natural radioactive decay of uranium and thorium in minerals of the region. People living in the North are now exposed to greater amounts of naturally occurring radionuclides than to radionuclides from anthropogenic sources. Historically, anthropogenic radionuclides in the Canadian North originated from atmospheric testing of nuclear and thermonuclear weapons between 1955 and 1963 and the radioactive fallout from the Chernobyl accident in 1986. Cesium levels in Arctic biota have generally declined since 1963 and fallout from Chernobyl has imbedded itself in soil and lake sediment. Other possible, yet small, sources of radionuclides include the burning-up of nuclear-powered satellites upon re-entry to the atmosphere, discharges from nuclear power plants and reprocessing plants, and nuclear waste dumping directly into the Arctic Ocean.8 The impact of the ocean disposal of nuclear waste remains unmeasured. Generally, levels of radionuclides in the air, water, or soil of the Canadian Arctic are similar to or lower than levels in more temperate areas.
Local sources of pollution within the Canadian Arctic include abandoned radar sites and military installations, northern mining activities, and local garbage dumps. Although these sources are not the principal cause of the widespread distribution of contaminants in the Canadian Arctic, they pose a threat to the health of local ecosystems by emitting a variety of pollutants (including POPs and heavy metals). It is estimated that approximately 0.2% of the Yukon and NWT landmass is contaminated by polychlorinated biphenyls (PCBs) from abandoned distant early warning (DEW) line sites. The Arctic Environmental Strategy Action on Waste Programs has inventoried several sites contaminated from these sources and their restoration is a priority for the Department of Indian Affairs and Northern Development.
NCP work indicates that the atmosphere is the most important pathway to the Arctic for POPs, heavy metals, and radionuclides and their transport is dependent on a number of factors, including the circulation patterns of global and Arctic air masses, temperature, and a phenomenon known as the "cold-condensation" effect, in which substances evaporate easily in warmer, temperate latitudes where they are used travel to the Arctic and condense in the cooler temperatures.9
Air temperature influences POPs transport; an increase in temperature results in a corresponding increase in the carrying potential of an air mass. Although summer air masses have the potential to carry larger amounts of POPs, predominant wind direction and additional atmospheric processes such as increased light-sensitive chemical activity, a build-up in moisture and resulting increase in rainfall remove contaminants from the air masses, actually decreasing the amount of contaminants transported to the Arctic in summer.
Future efforts to quantify POPs entering the Canadian Arctic will be confounded by distinguishing "new" sources of POPs from those that have been re-volatilized from previous deposition. For example, compounds such as hexachlorocyclohexane (HCH) may reach saturation levels in the oceans at certain times of the year, then are volatilized from the ocean to the atmosphere (a reversal of flux). They may then re-deposit or be transported out of the Arctic.
Oceans, rivers, and sea ice are additional transporters of contaminants to the Canadian Arctic, although the atmosphere is the most significant. Contaminants present in the atmosphere reach the Arctic in a matter of days, whereas contaminants transported by ocean currents and sea ice may take years or decades.
Spatial Trends: Location and Exposure
The diet of Inuit people in the eastern Arctic consists mostly of marine mammals, whereas Aboriginal peoples of the Mackenzie Valley region harvest mainly terrestrial wildlife, particularly large mammals such as caribou and moose.10 Fish is a seasonal staple across the Arctic. Organochlorine levels are generally higher in marine mammals, which feed at a higher level in the food chain and tend to accumulate larger fat reserves. Consequently, the estimated average intake of organochlorines is higher in communities that consume marine mammals than in communities that consume terrestrial mammals. This is evidenced by the human blood analyses conducted under the NCP.
Among Arctic communities with similar dietary dependence on marine mammals, differences in exposure to the heavy metals mercury and cadmium might be expected to be consistent with east-west differences in the levels observed in marine mammal tissues. Although marine mammals collected in the western Arctic were found to have higher mercury levels than eastern Arctic animals, blood mercury levels among Aboriginals are higher in the north and east than in the west. This finding supports the importance of the composition of diet, as marine mammals make up a smaller portion of the traditional diet of the Sahtu Dene/Métis from the western Arctic than of the Inuit from the eastern Arctic. Even though relatively high levels of total mercury and methylmercury have been measured in the commonly consumed portions of marine mammals, such as the meat (muscle) and muktuk (skin and blubber), the off-setting benefits of these components of a traditional diet have prompted health professionals to recommend no change in the amount of muktuk consumed by northern Aboriginals.
Many freshwater fish consumed by northern residents have mercury levels in edible tissues that exceed the consumption guidelines; however, no observed adverse health effects are associated with these elevated levels either in the fish or among humans. 11
Higher cadmium concentrationsattributed to the natural geology of the regionwere observed in marine biota from the eastern Arctic than in those from the west. In general, cadmium levels in the kidneys and livers of Canadian Arctic marine mammals are similar to levels found in terrestrial animals such as caribou and moose and as high or higher than levels observed in similar species in more temperate areas. Blood cadmium levels of people from western and eastern Arctic communities are not available for comparison.
In contrast to the observed spatial trends in heavy metals in the tissues of marine and terrestrial mammals, no clear spatial trends of the heavy metals cadmium and mercury were observed in waterfowl from the western and the eastern Arctic. Similarly, there were no clear spatial trends of POPs in seabirds. 12
The major organochlorines present in marine biota are PCBs and toxaphene. Unlike the spatial variation observed for heavy metals in marine mammals, the ranges in concentrations of organochlorines were generally similar among most marine mammals.
Spatial trends in contaminant levels in snow, air, and sediment provide insight into the sources and quantities of contaminants transported to the Canadian Arctic. Levels of contaminants measured in snow and air are subject to large variations attributed to a combination of factors including analytical methods, seasonality, and depositional trends.
Results from the snowfall measurements show hexachlorobenzene (HCB) and PCBs to be the most consistently distributed contaminants in snow samples. A comparison of HCH, dichlorodiphenyltrichloroethane (DDT), HCB, and PCB levels in snowfall in the Arctic and near Lake Superior, Ontario, indicated that the Arctic region is as polluted as regions to the south. These results support the importance of atmospheric transport in delivering contaminants to the Arctic. Spatial data for estimating air-borne contaminant levels of heavy metals are limited; therefore no spatial trends for air-borne metals in the Arctic currently exist.
Contaminant Levels over Time
The limited long-term data for Canadian Arctic biota levels of contaminants among air, snow, water, and soil demonstrate no consistent pattern over time; levels of some contaminants have increased while others have decreased.
Concentrations of organochlorines in marine mammals and sea birds declined in the period 1970 to 1980 and have recently leveled off. Levels of mercury and cadmium in ringed seals and beluga whales appear to have increased during the last decade in the eastern Arctic and in the last 20 years in the western Arctic. Levels of radionuclides in caribou muscle are decreasing: studies show levels from four to more than ten times lower than those measured in the 1960s.
Data from Arctic ice cores sampled for polyaromatic hydrocarbons (PAHs), PCBs, and lead generally reflect changes in the anthropogenic use and release of these contaminants to the global environment. From 1980 to 1993 there was a steady increase in PAH deposition. Data on PCBs indicate high deposition before 1969 followed by a significant decrease paralleling the discontinuance of production and use of PCBs in several countries. PCBs are still used in closed systems (electrical) and sometimes exist as microcontaminants. Despite the ban on their production, PCBs continue to be released into the environment; their rate of deposition to the Arctic was constant between 1990 and 1993. HCHs, one of the few organochlorine insecticides (lindane) still in large-scale global use, have been measured and show a decline from 1979 to 1993. The use of one form of HCH in particular, alpha-HCH, has declined dramatically in developing countries, contributing to a decline in overall HCH levels in the environment. This issue is complicated though, as often only the total HCH concentrations are measured.
Ice-core data from the Greenland Ice Cap show a decline in lead concentrations since the 1970s, coinciding with a decrease in the use of lead-alkyl gasoline additives in Canada, the United States, and Europe. Over a similar timeframe, lead concentrations in the air at Alert, NWT, have decreasedbut to a lesser degree. These results reflect the greater influence of Eurasian emissions at Alert.
Conflicting evidence from the sediment core data for mercury highlights the difficulty in determining whether its source is anthropogenic or natural. However, global atmospheric concentrations of mercury in the northern hemisphere have been increasing for the past several hundred years and anthropogenic releases to the atmosphere have been identified as the cause of a three-fold increase in global air and ocean surface water concentrations.13 The evidence from several Canadian Arctic sediment cores supports this conclusion.
It is imperative that we continue monitoring contaminant levels in the Arctic if we are to understand more completely the extent to which people and the environment are exposed.
Evidence for ecosystem effects in the Arctic as a result of contaminants is currently derived from studies on indicator species, comparisons of contaminant levels in Arctic wildlife with those in the same or similar species in locations where effects have been observed, and studies of biological responses based on biochemical indicators.
To date, no adverse effects have been reported in Arctic mink populations, which generally have lower contaminant levels than other North American mink populations. The tundra peregrine falcons did not suffer the extreme population declines experienced by southern populations in the 1 960s as a result of the pesticide DDT; however, eggshell thinning is evident. Because peregrine falcons are migratory, they are exposed to organochlorines in over-wintering habitats and the exposure contribution from the Arctic is difficult to determine. Levels of organochlorines in the eggs, blood plasma, tissue, and the prey species of the tundra peregrine falcon population nesting at Rankin Inlet are within the range that will result in failure of a portion of the reproductive attempts each year.
Some research was conducted under the NCP to identify biological responses to ecosystem stress in the Arctic, but the lack of significant dose-response data for Arctic animals limits our ability to draw clear conclusions. Moreover, determining effects of contaminants on populations of Arctic biota is difficult in the absence of 'healthy' comparative population data. The baseline population data for many Arctic animals, including polar bears, seals, and seabirds, are available for only 20 years, during which contaminant tissue levels have been relatively constant. Therefore, with the possible exception of the peregrine falcon, the effects of organochlorines on the health of Arctic wildlifein particular, marine mammalsat the individual or population level are inconclusive.
In Arctic ecosystems, there is a need to link measured biological effects in animals such as the polar bear, beluga, and narwhal with studies on population dynamics. Mean concentrations of the contaminant 2,3,7,8-tetrachlorodibenzo-pdioxin (TCDD) in polar bear liver and in walrus blubber from northern Quebec are at or above the threshold found for immunosuppression in North Sea harbour seals; however, concentrations of TCDD in Arctic ringed seal or beluga blubber are three to five times lower than those associated with impaired immune function (depressed leucocyte activity) in harbour seals. The effects of immunosuppression in Arctic wildlife may be obvious only during times of additional stress such as prolonged periods of starvation during which fat reserves and associated contaminants are mobilized. In the Canadian Arctic, the polar bear is probably at greatest risk from exposure to organochlorines because of its consumption of ringed seal tissue. Levels of TCDD concentrations in the tissue of ringed seal from the Canadian Arctic are at or near Canadian and United States tissue-guideline values established to protect fish-eating wildlife.
Caribou, beluga, and narwhal from the Canadian Arctic are exposed to high levels of heavy metals, especially cadmium, but the effects of the exposure are inconclusive. It is thought that Arctic biota may have adapted to relatively high exposure levels to metals and radionuclides occurring naturally in the Arctic.
Aboriginal peoples and scientists agree that a diet based on traditional foods has important nutritional, cultural, and economic benefits and a decrease in the consumption of those foods generally results in the loss of the benefits. Dietary shifts occur for a number of reasons, including a concern about environmental contaminants. Recent research suggests that poor diets and other lifestyle changes have contributed to the increasing incidence of diseases such as diabetes and cardiovascular problems among northern Aboriginals.14 Historically these diseases have been seen in low numbers in northern Aboriginal populations as a result of the benefits of a traditional lifestyle including traditional foods.
At present, the greatest risk associated with the consumption of traditionally harvested food is from exposure to certain organochlorines, especially chlordane, toxaphene, and PCBs, and to the heavy metals, including cadmium and mercury. Although concern about these contaminants has led to assessments of human health risk and decisions based on risk management procedures, such assessments do not always result in recommendations to limit consumption of country foods. Some nutritionists believe that the known benefits of a traditional diet outweigh uncertainties and risks associated with such a diet.
The few studies conducted suggest the greatest health concern is for the fetus, through transplacental exposure, and for newborns through breast-feeding.15 Maternal and cord-blood studies have been conducted in the Mackonzie-Kitikmeot region, Keewatin and Baffin regions, Nunavik, and Greenland to assess transplacental exposure to contaminants.16 Relatively high levels of organochlorines, mainly PCBs, measured in the cord-blood of newborns from some communities in the eastern Arctic may be related to a higher consumption of marine mammals.
The NCP and other research projects have yet to determine conclusively the implications of exposure for human health. Recent research associates dioxin, furan, and PCB levels in human milk with subtle clinical, immunological, and neurodevelopmental alterations in a group of infants and children from the Netherlands. A similar potential association between immune system deficits in infants and increasing PCB, dioxin, and furan levels in human milk is a preliminary indication in an ongoing study of Canadian Inuit. Very little is known about the inter-generational effects associated with long-term exposure to these contaminants.
Although the presence of elevated levels of some POPs in the milk of Inuit women has raised justifiable concern among nursing mothers in the Arctic, abandoning breast-feeding poses a far greater health risk than the few known and many unknown risks associated with infant exposure to contaminants through human milk.
In the Canadian Arctic, levels of lead in northern residents show no reasons for concern. Northern residents may be exposed to cadmium through the consumption of certain traditional foods such as organ meats (liver and kidney); however, the major exposure to cadmium in the North occurs through cigarette smoking. Human exposure to mercury is of particular concern because methylmercurythe organic form is bioaccumulative, biomagnifies, and is a potent neurotoxin. While there are no observed adverse human health effects directly attributed to exposure to methylmercury in the Canadian Arctic, this does not mean that there have been no effects. The CACAR states, "Methylmercury, in addition to other factors ... has likely collectively contributed to past and present socio-cultural problems within ... communities."17
In the Canadian Arctic, human body burdens of cesium, the anthropogenic radionuclide of greatest concern, have declined during the last 30 years, a phenomenon attributed to the decrease in above-ground nuclear weapons testing. Today, people who live in the North receive more than 95% of their radiation dose from naturally occurring radionuclides. Bioconcentration in the food chain may result in exposure to higher levels of some radionuclides, primarily the naturally occurring radionuclides lead-210 (210Pb) and polonium-210 (210Po), among people who consume large amounts of traditional foods.
Health Risk Assessment, Management, and Communication
In recognition of past improper approaches to managing risks related to food-chain contaminants and in communicating information to Arctic residents, the NCP partners promoted a more inclusive approach, involving communities more directly in the conduct of the risk management and communication processes. Determining the risks and benefits of continuing to eat a diet of traditional foods is a difficult challenge. Individuals, families, and public health officials must consider the potential risks from exposure to contaminants and the risks associated with abandoning a traditional diet, including its known nutritional, social, and economic benefits. Effective decision making and dissemination of information require that communities be involved in efforts to reduce exposure to contaminants without sacrificing the many benefits of a diet based on traditional foods. In the short term, this may mean reducing the consumption of certain organs or tissues of some animals known to accumulate high levels of contaminants, for example, burbot livers from Lake Laberge and Atlin Lake in Yukon and caribou liver in other regions of the North. Reducing consumption of certain foods in the diet, however, must coincide with increasing consumption of alternative, highly nutritious, locally available, and affordable foods.
In response to urging from the AES partners, a change to the Human Health Risk Assessment process was initiated under the NCP because it became clear that Aboriginal organizations must have the knowledge and capacity to be involved with health assessment decisions concerning their member communities. Where the NCP and its participants are concerned, the health risk assessment and management process now involves three main stages.
Traditional Knowledge and Local Observations
Many of the questions that researchers are working to answer involve information needs that can be satisfied only by long-term observation, detailed familiarity with the environment, the capacity to recognize changes and abnormalities in the environment, and continued sampling and monitoring. Traditional knowledge held by people living in northern communities has been accumulated through generations of year-round observation, sampling, and monitoring, combined with an intimate familiarity with the local environment. A number of NCP projects have taken advice from local hunters and Elders in identifying good sampling locations and times for their studies. In the investigation into the oceanography of the Husky Lakes, co-operation between Elders and scientists found four specific examples of traditional knowledge that led to focused scientific inquiry.18 However, the NCP is not a traditional knowledge study.
There is a growing recognition that traditional knowledge can also contribute to programme planning. There is a potential to use traditional knowledge to improve scientific approaches in hypothesis formation, research planning, and policy development, but this represents a significant challenge because there are few, if any, practical models of the specific application of traditional knowledge in scientific programme planning. Although the NCP has not formally attempted to collect and analyze traditional knowledge, information on local observations through feedback at workshops and community meetings has been recorded on an ad hoc basis and is described in the CACAR as an example of the types of information that can be gained from consideration of traditional knowledge (table 2).
Communication with Communities
In recognizing the importance of community-level communication, the NCP has devoted resources to the exchange of information and ideas between the programme and northern residents. This includes dissemination of programme results and extends to the development and provision of educational and communication tools related to contaminants and to the gathering of community concerns and priorities regarding contaminants. As a result of the efforts of the Aboriginal partners, NCP communications activities are now considered to be a responsibility of all programme participants. These activities include community workshops to exchange information on contaminants; discussion of NCP activities and research results with leaders, youth, and other community members; reporting on Aboriginal partners' projects and programmes; and support for the involvement of local contaminants committees or representatives in regional projects.
Inuit Tapirisat Canada (ITC) developed "Researcher Guidelines for Planning Communications and Community Participation," and work is under way at ITC on a guidebook for communities on their rights and choices in negotiating research relationships. ITC has also examined how communication occurred in a variety of contaminants incidents involving country food in Aboriginal communities and identified Inuit knowledge and communication needs regarding contaminants in three Inuit communities ("Communicating about Contaminants in Country Food").
The Denendeh National Office and Mackenzie Regional Health Service developed nutrition fact sheets to illustrate the nutritional and socio-economic benefits of Dene traditional foods and assisted communities in identifying alternative traditional food sources should health advisories affect their choice of diet.
The Métis Nation's Contaminant Education Program: Contaminants Curriculum Project has integrated contaminant information and materials with existing grade-school curricula and adult education programmes across the NWT. The Métis Nation-NWT has also published a lay person's guide to the NCP, which uses non-technical language to explain the main issues and concerns of the programme.
Council of Yukon First Nations' communications activities under the NCP have been integrated into a holistic environmental education programme that has included workshops and one-on-one consultations with community leaders and environmental representatives.
The Inuit Circumpolar Conference brought together approximately 500 participants from Chukotka, Canada, Alaska, and Greenland for a contaminants workshop as part of its 1995 General Assembly. Among the recommendations from the participants was a proposal to develop an Inuit International Action Plan to assist Inuit in working with contaminants researchers.
The NCP and Domestic and International Action on Contaminants
The use of NCP research is far-reaching. It is used to respond to community information needs and supports the need for action in domestic and international policy. NCP results have been critical in demonstrating the global importance of long-range transport of contaminants. Supported by leading-edge scientific evidence, NCP participants have raised domestic and international awareness of the immediate human health and environmental concerns of long-range contamination and have accelerated the pace of action towards control of such substances (table 3).
Chris Furgal is the Research Assistant with the Eco-Research Project at the University of Waterloo.
Robbie Keith is Executive Director of the Canadian Arctic Resources Committee.