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Greenland

A mixed diet

The heavy metals mercury and cadmium accumulate mainly in the liver, whereas POPs accumulate in fatty tissue. No effects on people from heavy metals or POPs have been found in Greenland.

One of the very few thorough studies of Greenlanders' diet was carried out in Disco Bay in the mid-1990s. It showed a mixed diet - the Greenlandic diet supplemented by imported western food products. "We concentrated on the Greenlandic part of the diet, not the imported part," says Poul Johansen, who has spent many years researching the routes followed by heavy metals and POPs in living organisms. Some of the research, which is cofunded by Dancea, is carried out at Denmark's National Environmental Research Institute in Roskilde.

Seal Liver

Quantitatively, the diet of Greenlanders in Disco Bay consists mainly of fish and seal meat. The absolutely dominant source of the diet's content of the heavy metals mercury and cadmium is seal liver. Seal liver constitutes only a small part of the diet, but is the main source of the diet's content of heavy metal.

In terrestrial animals, the levels of heavy metals are generally low. There are exceptions, however. For example, ptarmigan have high concentrations of cadmium in the liver, the only explanation for which must be that ptarmigan have naturally developed an ability to accumulate cadmium in their bodies - and live happily with that.

In freshwater lakes, high levels of mercury are found in, for example, non-migratory trout.

Comparisons

The content of heavy metals in animals varies from one region to another in Greenland, but not systematically as in the cases of POPs, the highest concentration of which is found in east Greenland and the lowest in west Greenland.

The same concentration of lead is found in people in both Denmark and Greenland. In the case of mercury, higher levels are found in the parts of Greenland where people eat a traditional Greenlandic diet. In the case of cadmium, there is no evidence that a high concentration of cadmium in the diet leads to a high concentration in the body. Most of the cadmium in the diet is presumably bound so tightly to proteins that it is not absorbed in the body. Smoking, on the other hand, greatly affects the body's content of cadmium. Cigarette smoke contains a lot of cadmium in an absorbable form.

Safety and selenium

The limit values for heavy metals in human diet have remained unchanged for many years. When the expression "limit value" is used, it sounds as though you will die if you exceed it. This is not so, but if you ingest heavy metals in quantities beyond the limit value, it may affect your health - for example, your nervous system - and have other invisible effects.

Poul Johansen says, "Many people who eat the Greenlandic diet ingest more cadmium and mercury than international limit values, and people who eat a lot of birds can reach lead concentrations around the limit value." However, there are no documented effects from heavy metals on human health in Greenland.

Selenium is interesting because there seems to be a relationship between selenium and mercury, with the selenium binding to the mercury so that it is not absorbed. Selenium binds to mercury in the ratio 1:1. So it is important where selenium is found and where mercury occurs. The main source of selenium is mattaq - whale skin - but selenium is also plentiful in other marine food. How does selenium get into the mattaq? Nobody knows - all one can say is: "that's nature!" Specific substances are concentrated in specific places in food. The fact is that there is a sufficiently large content of selenium in the Greenlandic diet to eliminate the current content of mercury.

Risk and good advice

Most of the cadmium and mercury load on the Arctic environment has probably always been there naturally. However, there is a contribution from the industrialised world, although the size of the contribution is not known. It is being investigated right now. It can be seen from analyses of marine deposits that there has been a rise in the content of mercury. Similarly, studies of peat bogs in different places in the North Atlantic region show a rise in the mercury load that peaked in around 1970.

There are considerable differences in the concentration of heavy metals found in marine animals. The very highest concentrations of mercury are found in the liver and kidneys of marine mammals, and the lowest in crustaceans, mussels and the flesh of fish and marine mammals. The same applies to cadmium. The higher we move up the food chain, the higher the concentrations. This applies particularly to cadmium - young birds contain almost no cadmium, whereas old birds can have a very high concentration of cadmium.

It is therefore advisable to eat as far down in the food chain as possible and to eat young animals rather than old ones.

Lead - A local problem

"Our studies indicate that lead shot is the main source of lead in Greenlanders' blood," says Poul Johansen. More than 200,000 guillemots are shot each year in Greenland. Lead residue from the shot is deposited in the carcasses and ingested by people when they eat the birds. That is one of the reasons why the Home Rule Government of Greenland proposes banning the use of lead shot for shooting birds.

In the areas around the old Greenland mines at Mestersvig, Maarmorilik and Ivittuut, higher lead values are still found in the fjords as a consequence of pollution from mining activities, and in Ivittuut and Maarmorilik people are advised not to collect and eat common mussels because they are contaminated with lead. However, there is no risk from eating fish, birds, and marine mammals from the old mining areas.

Unlike mercury, cadmium, and POPs, lead does not occur in increasing concentrations up through the food chain. It might be thought that when an eider duck eats mussels containing lead, it gets a bigger concentration than the mussels (because it eats lots of mussels), but that is not the case. Some of the lead is eliminated from the eider's body. It is the liver that cleans the body of lead. There is no lead in meat from Greenlandic animals, except birds shot with lead shot. Apart from these, the lead content of the Greenlandic diet is very low and does not constitute any risk to human health.

The dirty 16

DDT, PCB, HCH, toxaphene …Up to the present time, most effort has gone into getting the 12 worst environmental toxins - "the dirty dozen" banned. Attention is now turning to at least four others (and they will be followed by thousands more).

While heavy metals accumulate mainly in the liver, POPs accumulate partly in fat. Toxaphene is an insecticide that used to be widely used in the American cotton industry. High levels of toxaphene are found in Greenland, where cotton is not grown!

There are clear regional differences in the human PCB load in different places in the Arctic.

Whereas the PCB content of blood from people in southern Canada is relatively low, higher values are found in Nuuk, and even higher ones in Ilulissat; and the values in Ittorqortoormiit (Scoresbysund) set the world record. This geographical distribution accords well with the increasing importance of marine mammals in human diet as we move from Nuuk to Ittorqortoormiit, and with the fact that highest POP levels are found in east Greenland. There is concern that the high POP levels can affect people's health.

The content of another well-known spray agent, DDT, is very low in terrestrial animals. It is by and large in marine animals that the high concentrations of POPs are found.

Among birds, it is the kittiwake that sets the record. That is because the kittiwake spends the winter on the coasts of North America, where it receives a dose of POPs every year. Unlike the kittiwake, the black guillemot, which spends its whole life in the Arctic, has a lower load.

Eating the eggs of wild birds is particularly risky. The concentration of the pollutants in question is often high in such eggs. When the egg forms, the mother bird passes some of the pollutants that have accumulated in her body throughout her lifetime on to the egg. The mother bird thereby becomes a little "cleaner",  while the egg receives a dose of pollution.

A similar mechanism applies in the case of mammals, in which the POPs accumulate in fatty tissue. If a pregnant polar bear is exposed to POPs, the POPs will initially accumulate in the fat, but are carried round the body with the blood and thus delivered to the foetus. In both animals and humans it is in the foetuses rather than adult individuals that we can expect to see reproductive damage.

Summary

It may seem paradoxical that heavy metals and POPs are an environmental problem in Greenland when Greenland lies far from the sources of pollution, which are to found in the southern latitudes. Furthermore, most of Greenland's fish and prawns, which are its main export products, are among the cleanest in the world. Greenlanders are only exposed to a high load of heavy metals and POPs from their diet, which, unlike that of Europeans and North Americans, includes a large proportion of marine mammals and marine birds. If a Dane lived in the same way as a hunter from Scoresbysund and ate seals, whales and birds from Danish waters, he or she would probably take over the world record for PCB content in the blood.

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