Whales are contaminated with toxic metals that may come from the air they breathe rather than the water they swim in, according to research described in Hakai Magazine this month. In “Whales Rocked by Heavy Metals,” the author describes decades of research by marine toxicologist John Pierce Wise Sr. at the University of Louisville in Kentucky.

In 2010, after studying skin samples from 1,000 sperm whales, Wise’s team found that across 16 ocean basins, “from the Pacific to the Atlantic and near both poles, the whales had high levels of cadmium, aluminum, chromium, lead, silver, mercury and titanium.” More recently Wise’s team found that “whales in the Gulf of Maine are contaminated with toxic metals in concentrations similar to those seen in industrial workers with decades of exposure.”

No one knows yet whether the elevated levels of metals – including aluminum, chromium, iron, magnesium, nickel and zinc – are harming the Maine whales, he said, but there are concerns. “The carcinogens chromium and nickel, in particular, were as high as in exposed human workers who had died from lung cancer,” the article said. Although the cancer rate among the whales so far appears low, the presence of metals could be negatively affecting their reproductive success. “In laboratory experiments, chromium is toxic to whale testes. In humans, chromium is linked to decreasing sperm motility and fitness. Together, these findings suggest that metals might be contributing to reproduction problems in some whales, Wise says.”

The research team has not identified the source of the metals, but thinks they’re probably inhaled through the air by the whales, perhaps from pollution from industries near the Gulf.