Caribou in Canada's North are showing increasing levels of mercury, a contaminant that has drifted into the Arctic from other parts of the world, researchers have found.
Mercury is one of two contaminants found in northern environments that are of great concern to scientists, said Mary Gamberg, project co-ordinator with federal Northern Contaminants Program in the Yukon.
Gamberg said mercury "seems to be increasing in some [wildlife] populations all across the Arctic," she told CBC News in an interview Monday.
"In marine mammals, in some populations, it's increasing. And in caribou, in some populations — and particularly in female caribou — it seems to be increasing, which is really interesting," she added.
The contaminants program also monitors the amounts of cadmium in the North, but Gamberg said cadmium occurring in wildlife is due to natural sources and levels in animals are currently stable.
Mercury, however, is a major concern not just in the Arctic ecosystem, but also around the world, Gamberg said.
"The mercury is emitted down south, it comes up into the North, it falls out of the air because it's very cold here," she said.
"So we get a lot of mercury that isn't originated in the Arctic, but we get it. So it's in the environment and it's in the wildlife."
This year marks the 15th year that the Northern Contaminants Program has been annually testing the livers, kidneys and other body parts of caribou, moose and other northern animals.
Gamberg said the program has recently expanded to accept animal samples from the Northwest Territories and Nunavut. Researchers even received samples from Greenland last year, she added.
The contaminants program was set up in 1991, in response to northerners' concerns about eating traditional game animals that have been exposed to toxic substances drifting into the Arctic from industrialized regions elsewhere.
Health Canada recommends that people not eat more than 25 caribou kidneys a year from the Porcupine caribou herd, Gamberg said.
As for current research, Gamberg said scientists are studying why mercury levels in caribou are rising, particularly in female caribou.
Researchers will look at what caribou eat, including lichen, cotton grass and willows, to see where the elevated amounts of mercury are coming from.
This year's research will focus on the Porcupine caribou herd, Gamberg said. Researchers hope to study the Bathurst herd in the Northwest Territories next year.
Other studies are ongoing into mercury levels in other northern animals, she added.