Toxic metals in whales threat to humans: study
Sperm whales feeding even in the most remote reaches of Earth's oceans have built up high levels of heavy metals, according to U.S. scientists who warn the findings threaten human seafood.
A report noted high levels of cadmium, aluminum, chromium, lead, silver, mercury and titanium in tissue samples taken by dart gun from nearly 1,000 whales over five years.
From polar areas to equatorial waters, the whales ingested pollutants that may have been produced by humans thousands of miles away, the researchers said.
"These contaminants, I think, are threatening the human food supply. They certainly are threatening the whales and the other animals that live in the ocean," said biologist Roger Payne, founder and president of Ocean Alliance, the research and conservation group that produced Thursday's report.
The researchers found mercury as high as 16 parts per million in the whales. Fish high in mercury such as shark and swordfish — the types health experts warn children and pregnant women to avoid — typically have levels of about 1 part per million.
The whales studied averaged 2.4 parts of mercury per million, but the report's authors said their internal organs probably had much higher levels than the skin samples did.
"The entire ocean life is just loaded with a series of contaminants, most of which have been released by human beings," Payne said in an interview on the sidelines of the International Whaling Commission's annual meeting in Agadir, Morocco.
Payne said sperm whales, which occupy the top of the ocean food chain, absorb the contaminants and can pass them on to the next generation when a female nurses her calf.
Ultimately, he said, the contaminants could jeopardize seafood, a primary source of animal protein for 1 billion people.
"You could make a fairly tight argument to say that it is the single greatest health threat that has ever faced the human species. I suspect this will shorten lives, if it turns out that this is what's going on," he said.
Report raises key issues: whaling commissioner
Payne called his group's $5 million project the most comprehensive report ever done on ocean pollutants.
U.S. Whaling Commissioner Monica Medina informed the 88 member nations of the whaling commission of the report and urged the commission to conduct further research.
The report "is right on target" for raising issues critical to humans as well as whales, Medina told The Associated Press. "We need to know much more about these problems."
Payne, 75, is best known for his 1968 discovery and recordings of songs by humpback whales, and for finding that some whale species can communicate with each other over thousands of miles.
The 93-foot Odyssey, a sail-and-motor ketch, set out in March 2000 from San Diego to document the oceans' health, collecting pencil-eraser-sized samples using a dart gun that barely made the whales flinch.
After more than five years and 140, 000 kilometres, samples had been taken from 955 whales. The samples were sent for analysis to marine toxicologist John Wise at the University of Southern Maine. DNA was compared to ensure the animals were not tested more than once.
Payne said the original objective of the voyage was to measure chemicals known as persistent organic pollutants, and the study of metals was an afterthought.
The researchers were stunned with the results. "That's where the shocking, sort of jaw-dropping concentrations exist," Payne said.
Though it was impossible to know where the whales had been, Payne said the contamination was embedded in the blubber of males formed in the frigid polar regions, indicating that the animals had ingested the metals far from where they were emitted.
How that happened is unclear, but the contaminants likely were carried by wind or ocean currents, or were eaten by the sperm whales' prey.
Sperm whales are toothed whales that eat all kinds of fish, even sharks. Dozens have been taken by whaling ships in the past decade.
Most of the whales hunted by whaling countries — the major ones are Japan, Norway and Iceland — are minke whales, which are baleen whales that feed largely on tiny krill.