An 85-year-old vial of oil from a whaling ship has revealed that a mysterious group of organic chemicals resembling human-made compounds are naturally produced in the sea.
A decade ago, scientists monitoring marine mammals’ flesh for pollutants began finding unknown organic compounds containing the halogen atoms bromine and chlorine. More than 20 such compounds were eventually revealed. That raised alarms because the compounds, as complex halogenated chemicals, structurally resemble the pesticide DDT and polychlorinated biphenyls (PCBs), which were once used in flame retardants.
Manufacture of those and similar chemicals began in the 1930s. But their production and use were banned in most countries decades ago, after they were found to be deadly pollutants. Because halogenated compounds break down extremely slowly, they persist in soil and water and accumulate in animal flesh.
Researchers wondered whether the recently discovered organic chemicals were manufactured or produced naturally. Symbiotic bacteria in ocean sponges, for example, produce chemicals similar to DDT and PCBs that deter fungal growth.
To investigate, Emma L. Teuten of the University of Plymouth in England and Christopher M. Reddy of the Woods Hole (Mass.) Oceanographic Institution analyzed a whale-oil sample from 1921, before industry produced the first halogenated chemicals.
Their sample came from a jar of the translucent, yellow, odorless oil found on the Charles W. Morgan, one of the last whaling ships in operation. The ship is now preserved and on display in Mystic, Conn. “We were incredibly lucky to acquire it,” Reddy says.
The scientists found 11 of the organic compounds in the whale oil. Because of the oil’s age, the 11 compounds must have been produced naturally, the scientists conclude in their report online and in an upcoming Environmental Pollution.
“This by no means puts the chemical industry off the hook,” Reddy says. Industry will probably be pleased to hear that it isn’t responsible for the cleanup of additional compounds, he says, but the study “doesn’t say that Monsanto, the main producer of PCBs, is not responsible for PCBs that are found in the environment.”
The researchers argue that the naturally occurring compounds can shed light on the fates of the similar human-made ones. The recently discovered compounds must have been around far longer than DDT or PCBs, Teuten says, so researchers may be able to study the natural halogenated compounds to find out how industrial chemicals will continue to affect the environment.
Teuten and her colleagues say that they hope to determine where the new compounds are coming from and why they are being produced. The researchers are just beginning work to find out whether the compounds are toxic.
“I think the study is fantastic,” says Gordon W. Gribble of Dartmouth College in Hanover, N.H. Their work “really does show that nature makes these compounds.”
