Five years of research by a team of international scientists has found evidence of new chemical contamination throughout the Arctic.

The scientists work for the Arctic Monitoring and Assessment Programme (AMAP), set up in 1991 by eight Arctic countries.

Their report, based on research from 1991 to 1996, expresses concern that there are still too many gaps in our understanding of the pollution threats to the Arctic ecosystem.

But the London-based journal Pesticides News says the team identified persistent organic pollutants (POPs) as the main concern.

Pervading the environment

POPs are chemical substances which persist in the environment, accumulate in the food chain, and threaten adverse effects on human health and the environment.

All the POPs considered by the AMAP researchers have been found in air, snow, water and/or wildlife in the Arctic.

Contaminants travel long distances to reach the Arctic

Air monitoring in the region has found that the levels of two POPs, lindane and chlordane, show that they must have been carried there from the places where they had been used in the mid-latitudes of north America, Europe and Asia.

Exceptionally high levels of one POP, HCH (a mixture of alpha, beta, gamma and delta hexachlorocyclohexanes) were found in Russian river water, especially from the Ob in north central Russia.

DDT is still widespread in the Arctic, although in many countries it is restricted or has been abandoned.

It is still widely used in many parts of the tropics to control mosquitoes.

Eggs at risk

The levels of DDT in Russian rivers, even allowing for problems with analysis, show very high residues by comparison with urban areas of north America and western Europe.

Levels of DDE, a breakdown product of DDT, in Canadian tundra peregrine falcons are thought still high enough to cause thinning of the egg shells.

There is also concern about another POP, toxaphene, used in the Carribean as an insecticide in cotton production.

High toxaphene levels have been found in fish higher up the Arctic food chain.

Air, sea and ice are equally polluted

And in Greenland halibut toxaphene has been found at levels that may be enough to affect the development of bones in the young fish, and increase mortality during spawning.

Tributyltin, another POP, which is used as an anti-fouling paint on ships, is thought to be causing imposex (the imposition of male sexual characteristics on female genital systems) in invertebrates in some Arctic harbours.

The AMAP report says it is unlikely that POP levels are declining in the Arctic environment.

And it says it is not just older products that are cause for concern, but new organic chemicals as well.