But Asia also is probably contributing to the Pacific Northwest's problem. Airborne contaminants blow from China to North America in about a week. Salmon also probably pick PCBs up from Asia when they migrate into the North Pacific. Alaska's killer whales also are highly contaminated, even though there are no local dumps or sources, said Craig Matkin, a scientist with the North Gulf Oceanic Society. In the waters off Seattle and Victoria, killer whales aren't the only top-level feeders.
Human beings are, too.
People who regularly consume salmon or sole from Puget Sound face several health problems from the PCBs, including an elevated cancer risk. That has prompted Washington state officials to begin studying whether health warnings are needed regarding eating Puget Sound salmon and other fish. Eating two ounces per day, which is average for recreational anglers, increases cancer risk by one cancer for every 1,000 to 100,000 people exposed, according to a 1998 Puget Sound update by state officials. Government regulatory officials usually worry about cancer risks higher than one in 1 million. Because salmon is such a precious commodity in the region, the PCBs could become an explosive issue.