ANCHORAGE - A federal study has determined that dust from the huge Red Dog zinc mine in northwest Alaska causes little harm.
Researchers tested voles and small birds captured near the mine for toxic metals. The U.S. Geological Survey in cooperation with the National Park Service published the study this week.
The study found that metal-laden dust from the mine is not seriously harming small animals.
Ever since federal officials discovered large amounts of toxic metals on vegetation next to the mine's 52-mile road, they and the mine have been studying whether the dust that escapes from trucks using the road is causing biological harm.
The trucks daily carry zinc and lead concentrate from the open-pit mine - about 82 miles north of Kotzebue - to a Chukchi Sea port for smelter shipments.
The road passes through the Cape Krusenstern National Monument for about 20 miles.
The USGS dissected sparrows, common redpolls and six voles in lab experiments and found no "clear evidence" of serious biological effects, even though lead concentrations in the blood and livers of the birds and voles were about 20 times higher than similar animals collected from a reference site nearly 40 miles southeast of the road.
The USGS study follows on a Red Dog study looking at the risks from dust emissions. The mine's study, published last year, said the metal concentrations in the dust weren't high enough to harm human subsistence food such as fish, caribou or berries, but the dust was damaging tundra plants and might be harming small animals living nearby.
The mine, working with state environmental regulators, is creating a risk-management plan for dust emissions that might lead to additional controls. The Park Service and the USGS also are both working on additional studies of the dust's impact on tundra vegetation.
"We'll continue to look at this information and see what else we can do," said Red Dog environmental superintendent Jim Kulas.
Red Dog is the largest mine in Alaska and is one of the world's largest zinc and lead producers.