Danish researcher Rune Dietz, one of the lead authors of the study, said the impact is likely to vary across the Arctic region. In eastern Greenland, melting ice may give polar bears easier access to the breeding grounds of seal species with high levels of mercury.

However, at Svalbard in northern Norway, less ice could strand polar bears on land, keeping them away from mercury-rich seafood and forcing them "to eat more plants and terrestrial animals," Dietz told AP on Thursday.

For polar bears, high mercury levels can lead to a chemical imbalance in the brain that affects all aspects of the animal's behavior, survival and reproduction, the study said.

Traces of mercury are found in almost all fish and shellfish. At certain levels, it can harm the developing nervous system of a fetus or young child if too much tainted seafood is consumed by the mother or child. The World Health Organization says there are higher rates of mental difficulties among children in parts of the world that rely primarily on fish.

Inuit communities in the Arctic are at risk because their traditional diet includes seal, whale and to a lesser extent polar bear - species on top of the food chain that have accumulated high levels of mercury.

The AMAP report urged health authorities to communicate these risks to Arctic communities, but was cautious about offering diet recommendations because switching to a Western diet - and lifestyle - can lead to other health problems.

"Because the healthy food choices in local stores are quite expensive, if available at all, it is often more affordable but less nutritious processed foods that are chosen," the report said.

Combined with a more "sedentary" Western lifestyle, no longer focused on hunting and fishing, "this new diet increases the risks of developing obesity-related diseases, such as diabetes and coronary heart disease," AMAP said.

The report compiles findings from hundreds of published studies and builds on previous assessments in 1997 and 2002 which found that the pristine Arctic environment is polluted by industries in other parts of the globe.

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