Health Spectator

PBDEs (polybrominated diphenyl ethers) are the new PCBs

Sometimes things slip by us, and in this case we missed it because the initial report was about cats, not humans.

It seems that hyperthyroidism—a hyperactive thyroid—has become an increasing problem in house cats since the extensive commercial availability of polybrominated diphenyl ethers (PBDEs) in the late 1970s. PBDEs are used as flame retardants and are included in such common products as printed circuit boards and electronic components, TV and electronics housings, furniture, plastics, fabrics, and carpeting. Manufacture has concentrated on three basic varieties—penta, octa, deca—based on the total number of bromine atoms they contain. Within those classifications, the actual arrangement of atoms varies among the 209 possible combinations.

Because they are used extensively in products normally found in the home, PBDEs have become a major ingredient in house dust. And that, oddly enough, is how the cats are getting exposed to them. Swedish studies have shown that PBDEs contribute to neurological disorders and hormonal imbalances, including specifically—you guessed it—hyperthyroidism.

The U.S. Environmental Protection Agency (EPA) has linked PBDEs to liver, thyroid and nerve toxicity and states that they “are not chemically bound to plastics, foam, fabrics, or other products in which they are used, making them more likely to leach out of these products.” Animal studies have also shown a link to cancer.

The evidence for serious damage from PBDEs is sufficient that Sweden has banned all PBDEs since 2004. The European Union soon followed suit by banning the penta and octa forms of PBDEs (though not the deca). The state of Washington has banned penta and octa use since April, 2007, while some other states, including California, have similar bans in place or pending.

Americans, especially toddlers, most vulnerable

What should prove especially scary for Americans is the fact that studies show Americans have anywhere from 10 to 100 times the quantity of PBDEs in their systems that Europeans have. If that doesn’t worry you, consider the fact that studies in Norway and California have also shown that children—especially toddlers, who know how to get down and dirty with house dust—have higher PBDE levels than adults. This is significant because most of the permanent damage demonstrated in animal studies has come from prenatal or neonatal exposure to the toxins.

What’s more, a study sponsored by the EPA in 2004 showed high levels of PBDEs in supermarket food. Although this was a preliminary study to establish a sort of baseline, the results showed higher PBDE levels than similar tests conducted in Spain and Japan.

In fact, the U.S. is generally considered to carry the highest PBDE serum and environmental load in the world.

PBDEs still manufactured in U.S.

The good news is that the Great Lakes Chemical Corporation (now Chemtura), the sole U.S. manufacturer of PBDEs, phased out production of two of the three major classes of PBDEs in 2004. The EPA says it is discouraging any future production and use of these chemicals.

The bad news is that the decaPBDEs are still in use. With evidence mounting that they can degrade into the other forms that have already been proven harmful, many argue that the PBDE problem won’t go away until all forms of the chemicals are permanently banned.

“It is clear that Deca can debrominate as far as the hexas,” says Linda Birnbaum, Ph.D., D.A.B.T., and Director of the EPA’s Experimental Toxicology Division. “It is less clear that it can go all the way to give tetras under conditions that are environmentally relevant.”

Still, she says, “I think there is growing evidence that Deca and. . . its metabolites have the potential to cause toxicity in various animal species. Deca can be absorbed and is being found in wildlife and people.”