The Science of Sustainability

Cats, Chemicals, and Consumer Power

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Scientists believe that chemicals in your couch can be hurting you - and your cat.  Photo by gregbenzphotography.com.

Scientists believe that chemicals in your couch may be hurting you – and your cat. Photo by gregbenzphotography.com.

If you have an older cat, there’s a good chance it has high thyroid levels.  About 10 percent of older cats have this condition, called hyperthyroidism, which can cause weight loss, an unkempt appearance, and agitation.  Unfortunately, it requires lifelong treatment, usually a daily medication

Curiously, hyperthyroidism in cats was virtually unknown before 1979.  Another curious fact is that homes where cats with hyperthyroidism live tend to contain dust with higher levels of a certain flame retardant than homes with healthy cats.

Coincidence?  Not likely.  The flame retardant, called PBDE, is often found in polyurethane foam, which gives structure and softness to upholstered furniture.  When people sit down, PBDE poofs out and accumulates in house dust.  When cats groom themselves, they ingest the dust and the PBDE, which is structurally similar to thyroid molecules.

The human endocrine system is a set of eight glands that produce and secrete hormones.  Click to learn more about each function. Image courtesy Moss Greene & commonsensehealth.com.

Thyroid disorders are also on the rise in people.  According to the American Cancer Society, diagnoses of thyroid cancer have doubled since 1990.

But the problem is not just PBDE, and it’s not just thyroid disorders.  We are exposed to hundreds of other synthetic chemicals every day that have the potential to interfere with the body’s endocrine system, which includes the thyroid.  The endocrine system consists of glands and hormones that guide development, metabolism, puberty, and reproduction.  The endocrine system is particularly crucial in utero and during infancy because it orchestrates the development of organs.  A hormonal misfire during brain development can have lifelong effects.

Scientists are concerned about possible links between endocrine-disrupting chemicals and the rapid increase in conditions as varied as autism, ADHD, asthma, childhood leukemia, early puberty, autoimmune disorders, obesity, type-2 diabetes, infertility, and cancers of the thyroid, testes, prostate, and breast.

“We have a lot of diseases that have gone up in incidence with our increased use of [synthetic] chemicals since the 1950s,” said Heather Patisaul, an associate professor of biology at North Carolina State University.  “That suggests there is an environmental component.”

Linda Birnbaum, director of the National Institute of Environmental Health Science (NIEHS) and the National Toxicology Program, said, “What we’re looking for is not missing arms and legs or someone keels over and dies, but much more subtle kinds of effects which you might see over the course of a lifetime.”  She added, “If you don’t look, you don’t find.  Now that we’re starting to look, we’re starting to see associations.”

NIEHS is investing millions of dollars into research on the relationship between the endocrine system and chemicals such as flame retardants, pesticides, and BPA (often used in plastics, receipts, and can linings).  We ingest these chemicals with our food and water or by putting our hands in our mouths; we also absorb them through our skin and lungs.

In children, two long-running studies link PBDE exposure in utero and childhood to decreased IQ, attention problems, and problems with fine-motor control.  Photo courtesy Mary Hockenbery

In children, two long-running studies link PBDE exposure in utero and childhood to decreased IQ, attention problems, and problems with fine-motor control. Photo courtesy Mary Hockenbery

Hundreds of animal studies in recent years have provided experimental evidence linking endocrine disruptors and problems ranging from asthma to hyperactivity to cancer.  Patisaul’s studies on rats show an increase in anxiety, early puberty, and premature infertility with exposure to BPA at doses comparable to BPA exposure in average Americans.  She and her colleagues also showed that rats exposed to the flame retardant Firemaster 550 were more likely to be anxious and obese.

In children, two long-running studies link PBDE exposure in utero and childhood to decreased IQ, attention problems, and problems with fine-motor control.

Even though PBDE was phased out between 2005 and 2013, its replacements may not be any safer.  Under the Toxic Substances Control Act, manufacturers must notify the EPA when they bring a new chemical to market, but they are not required to provide safety data.

Patisaul said, “I don’t think people realize the vast majority of chemicals in their world have never been tested for any type of toxicity at all, let alone endocrine disruption.  That needs to change.  If we can figure out which chemicals are the bad actors, pull them out, and redesign products that are less likely to cause problems, I think that’s a good goal.”

Patisaul is on the scientific advisory board of an initiative called the Tiered Protocol for Endocrine Disruption (TiPED), established by Advancing Green Chemistry in collaboration with Environmental Health News.  TIPED connects chemical designers with organizations and scientists who can test the chemicals under development for endocrine disruption via computer modeling, cell studies, and animal studies.

“I don’t think people realize the vast majority of chemicals in their world have never been tested for any type of toxicity," Heather Patisaul, an associate professor of biology at NCSU

Other scientists are designing safer ways to use toxic chemicals.  At North Carolina State University, researchers are designing “cages” made of rings of sugar molecules to prevent flame retardant molecules from escaping into the environment except at high temperatures.  In tests, fabrics treated with the caged flame retardant were less flammable and used less flame retardant than fabrics treated the traditional way (washed in a bath of flame retardants, then cured in an oven).

Another force for change is the power of the consumer.  Patisaul cites BPA-free plastic bottles as an example.  “Regulatory agencies didn’t do it, the government didn’t do it.  It was the consumer demand for BPA-free products,” she said.  “It’s the consumer that’s changing the game.”

As for cats, there’s not much we can do to stop them licking dust off their fur.  But if we value our own health, we can learn from their experience.  Birnbaum said, “Sometimes there’s strong evidence from wildlife or even domestic animals. . . . We should be listening to those signals.”

Interested in testing your couch for flame retardants?  Check out this easy and free test at: http://foam.pratt.duke.edu/

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Category: Blog, Chemistry, Sustainable Health

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Mary-Russell Roberson

About the Author ()

Mary-Russell Roberson writes about all kinds of science in all kinds of media, from articles to exhibits to curricula. She is co-author of "Exploring the Geology of the Carolinas: A Field Guide to Favorite Places from Chimney Rock to Charleston." Although she thrives on variety, she does have some favorite topics: the earth sciences, the environment, natural history, epigenetics, medicine, and toxicology.
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  • Rosalind Dalefield

    When I was in final year of veterinary school in 1983, hyperthyroidism in older cats had already been known for decades, and was well understood. When I returned to study for my PhD in pathology in 1985, the historical histopathology slide collection included a large number of hyperthyroid thyroid glands from older cats, and many of the slides had been in the collection a long time. I don't know where you got the information that hyperthyroidism in old cats was 'virtually unknown before 1979' but it is completely incorrect.

    • Wendy Vernon

      A vet that I used to work for was taught in veterinary school that cats don't have anal glands. There is so much more that experts don't know than they do know.

      • Rosalind Dalefield

        That's absurd, you can SEE the anal gland orifices. I wonder what vet school that was?!

        • Wendy Vernon

          I don't know which school either but I thought that was crazy!

  • Rosalind Dalefield

    Most hyperthyroidism in older cats is due to 'hot' adenomas and here is a paper about thyroid tumours in cats and dogs from 1976: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2032435/

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