POPS in the Arctic

Due to global transport of POPs, substantial levels of these chemicals are present in the Arctic, in some cases at levels similar to those in heavily industrialised countries.

Thus, while countries from lower latitudes act as a source of POPs, the Arctic acts as a sink for some of these contaminants. Under cold Arctic conditions, POPs are likely to degrade at a slower rate than in temperate regions and will therefore persist in this environment for even longer.

Contamination of the Arctic environment will continue for many decades after cessation of POPs source emissions as a consequence of long-distance transport and the persistent nature of these chemicals.

Sources of Arctic POPs

Primary sources of POPs pollution in the Arctic most likely include the manufacture, use and disposal of industrial and agricultural chemicals in mid-latitudes of the Northern Hemisphere such as Europe, Russia and North America. For example, lindane and chlordane found in the Arctic environment have been correlated with long-range transport episodes from use areas in Europe and North America.

In addition, POPs discharged in the tropics are redistributed on a global scale and so may eventually reach Arctic regions. Monitoring sites in the Arctic have even detected specific discharges of POPs that have taken place in lower latitudes.

For example, a sudden use of DDT in former East Germany in the summer of 1983/4 was detected as a pulse by a Swedish monitoring program in the Arctic.

Within the Arctic environment itself, there are only a few known sources of POPs. These include dioxins and furans from smelters in Norway and PCBs from decommissioned military Distant Early Warning (DEW) sites in Canada. A recent study provided evidence for short-range redistribution of PCBs from the DEW sites up to distances of 20km.

Many of the organochlorine chemicals found to date in the Arctic have been banned or severely restricted in industrialised countries. However, this has not resulted in the substantial or rapid decrease in their environmental levels. For example, initial falls in PCB levels following cessation of manufacture throughout the 1970s and 80s have not been maintained and levels have generally only stabilised.

Levels of Arctic POPs

Studies on lake sediments in subarctic Finland show that detectable levels of PCBs and dioxins are present in surface sediments, representative of current day levels, but they decrease to below detection limits in deeper sediments representative of the 1940s or 1920s (Vartiainen et al. 1997). Therefore, these chemicals do not appear to be present in the Arctic before the chemical industry began to boom in the 1950s.

In Arctic air and seawater, hexachlorocyclohexane (HCHs) are higher than most other POPs. By comparison PCBs and DDT are low. However, the latter compounds are more lipophilic and bioaccumulate to higher levels than HCH in marine animals. They are also of greater toxicological significance.

Levels in Arctic food chain

Arctic marine food chains are generally simple. For example, phytoplankton-zooplankton-fish-seal-polar bear, or phytoplankton-zooplankton-whale (Harner 1997). POPs have been found to be present in microscopic plants (phytoplankton) and microscopic animals (zooplankton), which constitute the lower trophic levels of Arctic food chains (Hargrave et al. 1992).

Baleen whales such as the Bowhead whale feed on small invertebrates from the lower trophic level. These whales tend to have lower exposure to organochlorines and therefore lower tissue levels than species such as seals, narwhal and beluga whales which feed on fish, (the middle trophic level).

Similarly, species such as polar bears, which consume seals that are dependent on fish, tend to have the highest exposures to organochlorine contaminants.

The most frequently studied organochlorine POPs in Arctic marine mammals are the PCBs and DDT-related compounds. HCHs, HCB, chlordanes, toxaphene, dioxins and furans, dieldrin and endrin are less frequently measured. In addition, there are many other organohalogens that are known or suspected to be toxic to wildlife for which there is little or no data for Arctic wildlife. Such chemicals include about 22 chemicals that may exert similar effects to dioxin, including the brominated flame retardants, poly-brominated diphenyl ethers (PBDEs).

A Swedish study found PBDEs were present in ringed seal (Pusa hispida) in Svalbard, albeit at fairly low concentrations (47 ppb l.w. TeBDE) relative to PCBs. PBDEs are used as flame retardants in plastics and their presence in the Arctic confirms they have become widespread in the environment, even in remote regions.

There is evidence that marine mammals from Arctic waters have somewhat lower levels of organochlorines than animals from northern temperate latitudes, as may be expected from their location remote from sources. For instance a study that monitored levels of PCBs, HCHs, DDT and DDE in a range of marine mammals concluded that animals from the western North Atlantic were contaminated with about 15 times higher levels of organochlorines than animals from the Arctic Ocean (Mossner and Ballschmiter 1997). Similarly, levels of PCBs in common seals were two times higher in Iceland and 35 times higher in the North Sea and Baltic Sea

POPs in Arctic people

Individuals who are more highly exposed to POPs than the general population include those who consume large amounts of fish or sea mammals from contaminated waters. This includes a group of people who would least be expected to have high exposure to POPs - Indigenous Peoples from the Arctic who consume a traditional diet.

Levels of organochlorine pesticides in breast milk from Inuit women residing in Arctic Quebec were 4 times higher than women from Southern Quebec while levels of PCBs were 7 times higher. This is due to a relatively higher exposure to POPs from the consumption of sea mammals in the diet.

Furthermore, tissue levels of PCBs and dioxins in Greenland Inuit were 3 times higher than Inuit from Arctic Quebec. According to scientific studies, Greenlandic Inuit are one of the most exposed non-occupational groups to these compounds and represent a population for which the potential for adverse health effects may be particularly high.

For a detailed examination of the problems of POPs in the Arctic download "The Tip of the Iceberg" Report from August 1999 (pdf file)

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