Monday, October 15, 2007

"Mysterious seal deaths linked to chems"

By Doug Fraser

• In the 1960s it was DDT and PCBs; now brominated flame retardants, or BFRs, are causing alarm.

• All three chemical compounds are very resistant to being broken down by sunlight, heat, moisture and other factors in the natural environment.

• Modern chemists are looking to make new compounds that have a so-called fuse, an Achilles' heel that breaks the compound down into more natural, biodegradable components.

It's a great irony of the modern world that attempts to make us safer sometimes make us less so.

Fire causes billions of dollars in damage every year and kills thousands. Plastic items like small electronic gear and building materials are petroleum-based and would be very flammable if not for chemicals added during the manufacturing process known as brominated flame retardants, or BFRs.

When will it end?

But researchers are now finding that these chemicals have entered our food chain and might have a role in the recent deaths of hundreds of seals — and could ultimately be harming people as well.

"The highest levels (of BFRs) in the world are in the U.S., 10 to 40 times higher than Asia and Europe," said Susan Shaw, an environmental toxicologist attempting to solve the mysterious deaths of as many as 1,000 otherwise healthy adult harbor seals and gray seals along the New England coastline over the past three years.

The National Marine Fisheries Service declared two "unusual mortality events" for seals, one in 2004 and one in 2006. The declaration releases funding allowing a greater level of tissue sampling. Since 2006, researchers have sampled nearly 500 animals, most of which were dead. The die-off appears to be tailing off, with only 35 animals reported in 2007, but investigators have yet to find a clear cause, said NMFS spokeswoman Teri Frady.

Shaw said her analysis of harbor seal tissue samples from Maine, Cape Cod and New York showed high BFR levels.

"They are loaded with chemicals," Shaw said. Some evidence suggests BFRs could disrupt thyroid hormones and cause psychological and other long-term disorders, including cancer.

BFRs were an ingenious chemical discovery back in the 1960s. The bromine in the polybrominated diphenyl ethers (PBDEs) that are known collectively as BFRs combines aggressively with hydrogen atoms, robbing fire of an essential ingredient. That's why bromine is used in chemical fire extinguishers. By combining bromine ethers with highly flammable plastic, such commonplace items as computer housings, mattress foam and chairs now contain a built-in fire suppressant that helps them meet fire codes.

"The chair you're sitting in is probably 5 percent BFR," said Christopher Reddy, a chemical oceanographer at the Woods Hole Oceanographic Institution. BFRs make up between 5 and 50 percent of the material in our household products. Their molecules mimic one of the essential molecules produced by our thyroid gland.

"Think of them as keys into the keyhole of some molecular process in the body," Reddy said. "It throws a wrench into the system."

Unfortunately, BFRs do not stay put. They are constantly entering the environment as molecules sloughed off the material, or when BFR-containing items are broken up during disposal. They've been found everywhere, from remote Arctic regions to whales that stay far out to sea.

BFRs are extremely stable. They linger in dust, or travel with water, ultimately winding up in the ocean. There they latch on to microscopic plankton and start up the food chain, as bigger fish eat smaller fish with the chemicals stored in fatty tissue. At the top, are large predators, like seals, and us, eating cod, hake, pollock, and other large fish...

Alternatives do exist. There are three plastics that are self-extinguishing, but don't contain BFRs. Natural flame-resistant materials like leather, metal and glass could also be used, and design changes to products could make them less flammable. The BFR industry has already phased out the two most toxic forms of the chemical, but is resisting a ban on the most prevalent compound, known as deca-BDE....

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