Your Sofa Could Be Making Your Cat Sick

Housecats exposed to flame retardants found in sofas may be at greater risk for feline hyperthyroidism, a disease seen in one in ten middle-aged and older animals. Results of the study by researchers at Columbia University Mailman School of Public Health and Oregon State University appear in the journal Environmental Science Technology. The study was highlighted by the National Institute of Environmental Health Sciences as one of four “Papers of the Month.”

The study focused on 78 cats aged 7 or older with and without feline hyperthyroidism living in New York and Oregon homes. The cats wore silicone pet tags on their collars that picked up a variety of contaminants in the air for a week, and their owners filled out a questionnaire. The researchers have used a similar approach in silicon wristbands in studies of human exposures.

When they analyzed the silicone tags for flame retardant chemicals, the researchers found higher levels of Tris (1,3-dichloro-2-isopropyl) phosphate (TDCIPP, commonly called ‘TRIS’)—a common flame retardant found in stuffed furniture, air fresheners, and plastics—on the tags of hyperthyroid cats, in comparison to those worn by non-hyperthyroid animals. Among non-hyperthyroid cats, higher TDCIPP levels were associated with elevated blood levels of a hormone elevated in hyperthyroidism, potentially making them more likely to develop hyperthyroidism in the future. Higher concentrations of TRIS were also associated with households that use air fresheners and with cats who preferred to spend time on upholstered furniture.

Starting in 2004, one class of flame-retardant chemicals—polybrominated diphenyl ethers (PBDEs)—was phased out after research by Columbia Mailman Professor Julie Herbstman and others uncovered evidence of associated health risks. PBDEs were replaced by other chemicals, including TDCIPP, which had been banned from children’s sleepwear in 1977 due to cancer concerns. The amount of TDCIPP in use in the U.S. has risen more than 50-fold over the last 20 years; cases of feline hyperthyroidism have also climbed precipitously during this period.

Previous research suggested a link between PBDEs and feline hyperthyroidism, but this was the first study that focused on PBDE alternatives and feline hyperthyroidism and suggested that TDCIPP might have similar health effects.

“We all want a healthy home for our beloved animals and ourselves,” says Herbstman, a study co-author, director of the Columbia Center for Children’s Environmental Health, and professor of Environmental Health Sciences at the Columbia Mailman School. “In addition to being harmful to cats, there is evidence that TDCIPP exposure can disrupt the human endocrine system, although further research is needed. What we’re seeing in cats should be taken as a warning sign that exposure to these chemicals may disrupt the human thyroid system as well.”

The study’s first author is Carolyn M. Poutasse at Oregon State University. Additional co-authors include Darrell Holmes and Dezere Gonzalez at the Columbia Mailman School; Mark E. Peterson at the Animal Endocrine Clinic, New York; Jana Gordon, Lane G. Tidwell, and Kim A. Anderson at Oregon State University; and Peter H. Soboroff at the New York Cat Hospital. The study was supported by grants from the National Institute of Environmental Health Sciences (ES025505, ES007060) and other private support.