Chemical Flame Retardants Linked to Thyroid Disease in Cats

Finding could be a sign of possible health threat to humans, researchers say.

By Steven Reinberg
HealthDay Reporter
Wednesday, August 15, 2007; 12:00 AM

Copyright © 2007 ScoutNews, LLC. All rights reserved.

WEDNESDAY, Aug. 15 (HealthDay News) -- A mysterious epidemic of thyroid disease in pet cats in the United States may be due to dust from fire-retardant chemicals used in carpets, furniture, mattresses, electronic products and even pet food, researchers report.

And while the researchers said there's no evidence to suggest a threat to humans posed by the chemicals -- called polybrominated diphenyl ethers (PBDEs) -- they can't rule out the possibility.

"Cats are very highly exposed to these chemicals, and the levels in cats are higher than the levels in people," said researcher Linda S. Birnbaum, director of the Experimental Toxicology Division at the U.S. Environmental Protection Agency. "But cats may be a good indicator of indoor exposure to humans," she added.

Symptoms of hyperthyroidism in cats include weight loss, increased appetite, hair loss and irritability. Hyperthyroid cats could serve as modern-day versions of the canaries in coal mines that alerted miners to poisonous gas, said Birnbaum, who added that hyperthyroidism is treatable in cats as well as people.

Feline hyperthyroidism is one of the most common and deadly diseases in older cats, and indoor pets are thought to be at greatest risk, Birnbaum said. Because of their conscientious grooming, cats ingest large amounts of house dust containing PBDEs.

Concerns about health effects from PDBEs began in the late 1990s, and studies have found that the chemicals cause liver and nerve toxicity in animals. "In addition, a recent study found an association with house dust and the levels of PDBEs in breast milk in women," Birnbaum said.

Many PBDEs, such as penta, which was used in polyurethane foam for furniture cushions and pillows, have been phased out either voluntarily by manufacturers or by bans from states and the U.S. government and governments overseas.

Despite these bans, BBDEs are environmentally persistent compounds, so it will take a long time before they disappear from the environment, Birnbaum said.

She noted that the EPA is looking for safer alternatives to some of the chemicals that will be fire resistant but not pose a potential health threat to animals or humans. So far, 14 alternative flame retardants have been evaluated, and furniture foam manufacturers are using new alternatives, according to the EPA.