Public release date: 15-Aug-2007

WASHINGTON, Aug. 15, 2007 — A mysterious epidemic of thyroid disease among pet cats in the United States may be linked to exposure to dust shed from flame retardants in household carpeting, furniture, fabrics and pet food, scientists are reporting in a study scheduled for publication the Aug. 15 online issue of Environmental Science & Technology, a semi-monthly journal from the American Chemical Society, the world’s largest scientific society. Janice A. Dye, DVM, Ph.D., at the U. S. Environmental Protection Agency in Research Triangle Park, N.C., and colleagues from there as well as Indiana University and the University of Georgia, report evidence linking the disease to exposure to environmental contaminants called polybrominated diphenyl ethers (PBDEs), which the researchers found to be elevated in blood samples of hyperthyroid cats. Their findings were based on analysis of blood samples from 23 pet cats, 11 of which had the disease, termed feline hyperthyroidism (FH). PBDE levels in the hyperthyroid cats were three times as high as those in younger, non-hyperthyroid cats.

Concerns about the possible health effects of PDBEs arose in the late 1990s, and studies have reported that PDBEs cause liver and nerve toxicity in animals. FH is one of the most common and deadly diseases in older cats, and indoor pets are thought to be most at-risk. For starters, cats ingest large amounts of PBDE-laden house dust that the researchers believe comes from consumer household products

The danger of contracting feline hyperthyroidism might be greater in America, where people have the highest reported PBDE levels worldwide, the study said. Also, by the late 1990s, North America accounted for almost half of the global demand for PBDEs from commercial materials like furniture or upholstery, the report added.

The epidemic of hyperthyroidism in cats began almost 30 years ago, at the same time when PBDEs were introduced into household materials as a fire-prevention measure. Although the disease was first discovered in the U.S., it has since been diagnosed in Canada, Australia, Japan and many parts of Europe. Hyperthyroid disorders have also increased in humans—former President George H. W. Bush and First Lady Barbara Bush have the disorder, and even Millie, their Springer Spaniel, had contracted it.