Canadian scientists investigating the PCB content of breast milk among the women of industrial southern Quebec needed samples of milk from an unadulterated environment for reference purposes. They took the necessary samples from Inuit women in Arctic Canada. They were shocked when the results came back from the laboratory. The Arctic mothers had five times as much PCB in their milk as the women further south.46
The survey was carried out in the mid-1980s and was one of the first alarming signs that organic pollutants able to pose a threat to both humans and animals, were found in the seemingly pristine Arctic landscape, far from any sources of industrial pollution. Since then, a considerable amount of research has been done to map the presence of organic pollutants in the Arctic. The problem has comprised a central issue in the work carried out by the eight Arctic nations that recently formed the Arctic Council. One of the most significant results of this work to date is an 800-page report entitled The AMAP Assessment Report: Arctic Pollution Issues, published in 1997.
The report describes the systematic transport of Persistent Organic Pollutants, such as PCB, from warmer to colder areas by way of air currents. In effect, the Earth's atmosphere functions like a giant oil refinery, separating different compounds at different latitudes, in accordance with the temperatures at which they condense. Heavy metals like mercury and cadmium are also transported polewards, in part by the ocean currents. The situation is made worse by the fact that organic pollutants decompose far more slowly in die Arctic environment than they do further south.
Organic pollutants filter into the food chain where they are dramatically concentrated as they progress from link to link. In this way, they pose a greater threat to species eating marine mammals than to the marine mammals themselves.
Organic pollutants bind themselves to fatty tissues and it is therefore those cultures that consume considerable amounts of seal or whale blubber that are the most vulnerable. This applies to most Inuit communities, particularly the smaller villages that still maintain hunting traditions, and where imported food is very expensive. It also applies to the Faroe Islanders. In the Faroes, the blubber of pilot whales constitutes an important part of the traditional diet. 75% of women in northern Quebec and Labrador and 95% of women in Greenland have a higher PCB level in their blood than «the level of concern» of 5 parts per million defined by the Canadian health authorities.47 Organic pollutants are transferred to infant through their mother's milk. Surveys carried out in the US show that PCB can be harmful to the development of the central nervous system.
In the animal kingdom, the polar bear is vulnerable to organic pollutants as its diet consists primarily of seal. Very high levels of PCB have been found in the polar bears of the Svalbard region.
Whale and seal meat is lean and therefore contains only a minimal amount of such organic pollutants. The meat can, however, contain heavy metals, although these normally confine themselves to the liver and kidneys. Pilot whale meat contains relatively large amounts of mercury. We do not know how much of this comes from natural sources on the sea bed and how much comes from human pollution. It would seem that the pilot whale has developed a high level of tolerance with regard to mercury - in addition to a pollution immunity mechanism. Owing to its special diet, the pilot whale carries a higher level of mercury than other species of marine mammals in the North Atlantic. In general, toothed whales carry a higher level than baleen whales.
Research carried out in the Faroe Islands on the consequences of eating pilot whale products concludes that there exists a statistically significant connection between mothers carrying high levels of mercury when pregnant and a negative effect on the power of concentration and memory among their children at the age of 11. This does, however, only concern what is referred to as «subtle effects».48
So far, no surveys have been carried out on the possible negative effects of consuming organic pollutants through eating whale blubber. Until now, the Greenland diet has been considered a very healthy one, and cardiovascular diseases and diabetes, for instance, are very rare in Greenland.
The authorities of the whaling and sealing nations will be faced with a difficult task when weighing the possible negative effects on people's health caused by the ingestion of organic pollutants through eating marine mammal products, against the cultural, economic and social consequences of a move away from the traditional diet based on local resources. The task will not be made easier by the fact that neither the magnitude nor the nature of the risk is well documented.
(Click the image for full-size version and caption.)
Marianne Jensen, member of the Greenland Home Rule government responsible for health, environment and research, warns against panicking over organic pollutants, stressing that in general the food in Greenland is healthy.49 The problems arise when the diet lacks variety, and people eat blubber for «breakfast, dinner and tea». The Greenland authorities plan to appoint a nutrition committee whose task will be to develop official nutritional guidelines.
Traces of organic pollutants can be found in all food, so there is no question of setting a zero limit. The question is how high a level of consumption can be allowed before the risk becomes unacceptable. The Faroese authorities have already issued advice to the public on what levels of pilot whale meat and blubber they consider safe to eat, and have warned against eating the kidneys of pilot whales, which are traditionally considered a delicacy.
A people's diet, however, is not only about health. Dave Ramsden, Canadian North West Territories' deputy minister of health, says that, «If we start a stampede away from eating beluga or caribou we will have lost the people's culture.»50
The fishing industry in the northernmost North Atlantic fears that information on the poleward movement of organic pollutants will cause unfounded concern in the markets and hurt sales. «The Arctic environment is relatively clean,» -says Jens Hansen of the Centre for Arctic Environmental Medicine in Århus, Denmark51. There is no health hazard associated with eating fish or marine mammal meat from these areas. Surveys of the fish-eating harbour seals off the coasts of Germany and the Netherlands and further north along the Norwegian coast, show a decline in the level of organic pollutants the further north and away one goes from the major population centres and sources of industrial pollution.It has been claimed that organic pollutants comprise such a threat to marine mammal stocks in the North Atlantic that all whaling and sealing must cease immediately.52 However, the level of organic pollutants among most of the stocks in the northernmost North Atlantic are relatively low, and there is no evidence of reproductive problems. Indeed, there are success stories of extremely high reproductive rates in seal and whale stocks in some of the more heavily polluted areas, such as harbour seals of the Wadden Sea, sea lions off California, grey whales off the west coast of Mexico and the US, and grey seals off Scotland and Ireland. And in general, reports from around the world give the story of «rising tides of whales».
Whatever the case, everyone agrees that there is cause for concern. In extremely polluted coastal areas, reproduction problems and disease caused by organic pollutants have been recorded among marine mammals. Though cleansing programs have had some success, as in the North Sea and the Baltic, new chemicals are being introduced whose effects are difficult to predict. The production and use of a number of organic pollutants, including PCB and DDT, has now been banned in many countries, yet scientists tone down their optimism. Much of the PCB that has already been produced will find its way north over the next few decades.
It is nonetheless reassuring to observe that the shocking discovery of organic pollutants in the «pristine» Arctic has had political consequences. «Arctic contamination is now driving international negotiations to toughen controls on POPs (persistent organic pollutants) and heavy metals,» says David Stone, chairman of the scientists who wrote the AMAP Assessment Report: Arctic Pollution Issues.53
Notes:
46. Fred Pearce, Northern Exposure, in New Scientist (May 31, 1997).
47. See note 46.
48. The information stems from the abstract of an unpublished paper, Cognitive deficite in 7-year-old children with prenatal exposure to methylmercury, presented at the International Conference on Human Health Effects of Mercury Exposure, in Thorshavn, June 1996, and from personal communication with one of the authors, Pal Weihe, Department of Public Occupational and Public Health, Faroese Hospital System.
49. Interview published in the Greenland newspaper Sermitsiak, May 30, 1997.
50. See note 46.
51. Personal communication.
52. See, amongst others, the report entitled Under Fire: Environmental Threats and the Extinction of the World's Cetaceans, published in 1994 by the Environmental Investigation Agency.
53. See note 46.