ENVIRONMENT : Hunt Is On for Pollutant Traces in Bering Sea : Alaska villagers, scientists wonder if toxic substances are endangering animals and people who eat them.

Five or six miles from shore, in the slushy subarctic wilderness of the Bering Sea, three Inupiat hunters stand on an iceberg and prepare to butcher an eight-foot-long bearded seal. They had shot the animal minutes earlier from their aluminum skiff, and climbed onto the ice to retrieve it.

For generations, scenes like this have played out up and down the Alaska coastline. Hunts for seals, walruses and whales are the mainstays of still-thriving subsistence cultures in dozens of indigenous settlements, with hundreds of animals taken each year.

But this hunt is different. And as the men set to work, they do something that’s becoming a modern-day tradition for some of Alaska’s native hunters.

“Jack, why don’t you be the doctor?” suggests one of the men, Charlie Johnson. His 32-year-old nephew, Jack Johnson, nods.

Then he slips on a pair of rubber gloves, wipes clean a titanium-blade knife and begins cutting tissue samples from the seal to be sent off and tested for PCBs, DDT and nearly 50 other industrial and agricultural pollutants that have begun turning up in small amounts in northern seas.

If this seal is like other marine mammals tested off Alaska in recent years, it won’t be a question of whether there are poisons in its blubber and internal organs. The question--asked increasingly by villagers, scientists and government agencies--is how much, and whether the substances are dangerous to the animals and the people who consume them.

The hunters were accompanied by Paul Becker, a Maryland-based scientist from the National Marine Fisheries Service. Becker has been coming out with native hunters like this since 1987, collecting samples for a national marine mammal tissue bank. He has trained several groups of villagers in Nome, Barrow and other settlements to take samples as part of their regular hunts.

Becker and other scientists are just beginning to amass enough samples to reach a conclusion: Many different man-made contaminants are turning up in marine mammals in the farthest reaches of Earth, including the Arctic. Researchers in Canada and Greenland are reporting the same thing. Among the most common are pesticides and PCBs, or polychlorinated biphenyls, used in electrical equipment and in the manufacture of paints and plastics that have been linked with cancer and reproductive problems.

Such substances have long been found in waterways and oceans at lower latitudes. Scientists think that they are drifting here on atmospheric and ocean currents from near and far. Air and water currents in the Arctic tend to trap contaminants on the polar icecap, scientists say.

The concentrations turning up here are generally low--for the most part well under amounts typically found in seals and sea lions in more industrialized areas, such as off the coast of Southern California.

The contaminants collect in water and in mud on the sea bottom and travel up the food chain. The highest amounts turn up in some of the larger sea mammals, such as beluga whales and polar bears, which have relatively long lives and tend to concentrate toxins in their fat and internal organs.

All of this has caused no small amount of anxiety in the villages, where oil from rendered seal fat is a staple consumed like salad dressing and where people routinely dine on dishes such as dried seal meat, walrus heart and whale steaks.

“There’s definitely a lot of concerns in the villages,” said Charlie Johnson, who is also executive director of the Eskimo Walrus Commission, a native group that works with the government to help manage Pacific walrus populations.

“We’ve seen a huge increase in cancer rates. People hear about these things turning up and wonder if that has anything to do with it. I don’t think there’s enough known yet to say there’s a problem here in Alaska . . . but I think we have to be aware that we could have a problem eventually,” he said.

Public health agencies have consistently held that toxins in Alaska marine mammals are at such low levels that there’s little risk to people--or whatever risks exist are outweighed by the benefits of eating such foods. A team from the Centers for Disease Control and Prevention tested elders from two indigenous communities who had eaten walrus and other marine mammals their entire lives and found nothing out of the ordinary.

Becker, an ecologist, said he believes that contaminant levels are low enough not to be of immediate worry in Alaska, but that could change if levels continue rising.

And health officials here are trying to get money from the federal government for stepped-up monitoring for toxins in the villages. They point to Canada, Finland and other northern countries, where much more testing has been done--everything from checking breast milk for PCBs to taking hair samples for heavy metals.

“Here in the United States, we haven’t done squat,” said Dr. John Middaugh, Alaska’s state epidemiologist. “We need to do a lot more work documenting what’s here and whether it’s changing. We need to call attention to the world that the Arctic can’t tolerate the continued long-term transportation of these things into our ecosystems.”