There’s an epidemic of thyroid disease in the U.S. and no one seems to know quite why. It has been quietly growing for years.
Just check the number of prescriptions filled for thyroid medicine and you’ll realize that there is something strange going on. Synthroid is the fifth most prescribed drug in America, with 25 million bottles dispensed last year. When you add in generic levothyroxine plus products like Armour Thyroid, Levothroid and Levoxyl, the total comes to nearly 90 million.
That doesn’t even count the millions of people with undiagnosed thyroid problems. Some experts estimate that as many as one out of five women over 60 are suffering from “subclinical hypothyroidism” (American Family Physician, Oct. 2005).
That makes thyroid disorders among the most common conditions affecting Americans. What accounts for this epidemic?
The experts don’t have good answers, but house dust is one possible culprit. The dust itself is not the problem. But chemicals carried on dust may be partly to blame.
Dustborne compounds called PBDEs (polybrominated diphenyl ethers) have been used for years as fire retardants. They can be found in mattresses, carpets, couches, computers, TVs and cell phones.
Although it seemed like a good idea to protect flammable furniture like couches and mattresses, scientists didn’t anticipate that fire-retardant chemicals would end up in us. But Americans have levels of PBDEs in their bodies that are 7 to 35 times higher than those in Europeans (Environmental Health Perspectives [EHP], May, 2008).
Most European countries banned some PBDEs years ago. Americans, however, are still being exposed. When these chemicals get trapped in house dust, they can be easily transferred to skin and lungs.
Cats may be serving as the canaries in the coal mine. Veterinarians began noticing an epidemic of feline hyperthyroidism in the 1980s. This corresponds to the introduction of PBDEs. When cats groom themselves, they are exposed to chemicals in house dust. Recent research confirms that the hyperthyroid cats have high levels of PBDEs circulating in their bodies (EHP, Dec. 2007).
Young children crawling on the floor or carpet are also exposed to relatively high levels of house dust and PBDEs as well. Thyroid hormone imbalances during development may affect the brain.
Adults with an underactive thyroid gland may experience symptoms such as fatigue, constipation, dry skin, lower libido, depression, brittle nails and elevated cholesterol. Worse, even mild hypothyroidism may increase the risk of fatal heart disease (Archives of Internal Medicine, April 28, 2008).
Diagnosing and treating thyroid problems can be complicated. Our Guide to Thyroid Hormones has information about interpreting tests, selecting treatments and drugs that can affect thyroid function. It can be downloaded for $2 from this Website.
Although we don’t know why so many Americans have thyroid problems, PBDEs are one suspect. Getting them out of the environment will be a major challenge.