Flame retardants that were banned 40 years ago from children’s clothing are still being used to make furniture today.
Recent research conducted at Oregon State University’s College of Agricultural Sciences looked at flame retardant chemicals commonly found in furniture to determine if there may be a correlation between exposure to these chemicals and feline hyperthyroidism.
For seven days, 78 cats had one-of-a-kind tags dangling from their collars, absorbing any chemicals the cats encountered. Analyzing the tags for chemical exposure promised insight into potential causes of the illness.
Feline Hyperthyroidism has reached epidemic proportions. The number of cats diagnosed with it in 1980 was 1 in 200. Today, it’s estimated that 1 in 10 cats are afflicted. No one knows why, but a recent study by Oregon State University indicated feline hyperthyroidism may be explained by exposure to a chemical contained in flame retardants commonly found in furniture.
The disease almost always afflicts older cats – 10 years and older – and can be difficult and expensive to treat. In sick cats, you’ll see weight loss despite an increased appetite, as well as nervousness, increased activity, rapid and pounding heartbeat, increased thirst, matted fur, and shedding.
After the tags were collected, owners filled out a questionnaire. The tags then went through a process to extract the chemicals by soaking them in a solvent.
The feline passive samplers – similar to a rabies tag – are produced out of the same material used in the silicone wrist bands invented in the lab of Kim Anderson, an environmental chemist in the OSU College of Agricultural Sciences. She originally developed the material to measure chemical exposure in humans—largely in response to environmental concerns surrounding Hurricane Harvey, which ravaged our nation’s petrochemical hub in 2017 and released toxins from chemical plants, refineries, and Superfund sites.
“The tags are porous and chemically very similar to human cells,” Anderson said. “Molecules of contaminants embed themselves in the silicone in the same way they’d go into the cells in your body. The silicone is a pretty good mimic of how our skin absorbs different types of chemicals – what we call passive sampling.”
The research on hyperthyroidism, led by Carolyn Poutasse, a doctoral student in Anderson’s lab, found over 20 individual flame retardants in at least one tag. But only levels of tris (1,3-dichloro-2-isopropyl) phosphate, or TDCIPP, a flame retardant once found in children’s sleepwear and discontinued for that use in the late 1970s, differed between tags worn by hyperthyroid and non-hyperthyroid cats. TDCIPP is still commonly applied to the foam in upholstered furniture, some plastics and some gel air fresheners.
Even in healthy cats, higher chemical levels correlated with higher thyroid hormone levels.
“The way a cat is diagnosed with feline hyperthyroidism is by extremely elevated concentrations of thyroid hormones,” Anderson said. “Seeing the correlation is suggestive of a connection between thyroid function and exposure to TDCIPP.”
Two cats in the same household can absorb different levels of the flame retardant, Poutasse said, because one cat may spend more time on furniture and the other on windowsills or other areas without flame retardant. Covering furniture to provide a barrier and reducing air freshener use may help lower a cat’s exposure.
The findings have led researchers to think about hyperthyroidism in humans. Even at the cellular level the benign tumor associated with feline hyperthyroidism is identical in cats and humans. Extrapolating from that, hyperthyroid cats could be sentinels for humans, warning of a possible link between flame retardants and human hyperthyroidism.
“Of course, that begs the question, if we follow these cats for five years, would those cats on the higher end of normal thyroid hormone levels continue to progress to have higher and higher levels assuming their exposure to TDCIPP continues to be elevated?” Anderson said. “That would be the natural question if cats end up with hyperthyroidism.”
The amount of the chemical in use in the U.S. continues to rise, Poutasse noted. In 1997, demand for the flame retardant was 450 tons and in 2006 it was 22,700 tons, according to a review in 2012. Scientists are beginning to look not only at the organophosphates in flame retardants, but also the derivatives. Anderson and Poutasse plan to continue evaluation of over 1,500 chemicals not measured in the current study.
“When you look at the environment, you’re immediately struck by: ‘Well, this wasn’t diagnosed in the ‘60s and ‘70s and now it’s 1 in 10,’” said Anderson. “What chemicals came on the market in that time period? One of the biggest ones is flame retardants.”
The study was a partnership between OSU’s Food Safety and Environmental Stewardship Program, the OSU Carlson College of Veterinary Medicine, Columbia University, the New York Cat Hospital and Dr. Mark E. Peterson of the Animal Endocrine Clinic in New York City, the first veterinarian to document feline hyperthyroidism.
By Kym Pokorny