Cats as canaries for thyroid disease

Hyperthyroidism is a leading cause of illness in cats, and the first reports of the feline disease in the late 1970s coincided with the first reports of environmental contamination arising from polybrominated diphenyl ethers (PBDEs), which are used as flame retardants in household products such as carpeting and televisions. Structural similarities between some PBDEs and the hormone thyroxine, along with toxicological studies, have led researchers to suspect a link between PBDEs and thyroid dysfunction. In a new study, a team led by EPA's Janice A. Dye reports that blood PBDE levels in cats are 20 to 100 times greater than those of adult humans (Environ. Sci. Technol., DOI: 10.1021/es0708159). The researchers hypothesize that the elevated PBDE levels stem from canned cat food (primarily fish) and PBDE-laden household dust ingested while grooming. They propose that cats could be sentinels—akin to canaries in coal mines—for human thyroid problems associated with chronic PBDE exposure.