Your Nail Polish Might Be Making You Gain Weight

A toxic chemical has been found in certain polishes.

Red nail polish being applied
(Image credit: Getty)

Your favorite brand of nail polish might have a hidden ingredient that can wreak havoc in your body. Researchers at Duke University and the Environmental Working Group have pinpointed a common polish ingredient that may be dangerous, especially for people who frequently paint their nails. 

Triphenyl phosphate, or TPHP, makes nail polishes more flexible and durable, and is also used to make plastic and to stop foam furniture from catching fire. It may have been introduced to nail polishes to replace phthalates, which studies have linked to reproductive issues. But the replacement might not be that much of an improvement. 

Separate studies have shown that TPHP is an endocrine disruptor, which means it interferes with hormones, and tests on animals have shown reproductive and developmental problems as a result. In humans, scientists say it may be linked to weight gain, but further studies need to be done before they can say anything conclusively. 

The chemical is included in 49 percent of more than 3,000 nail polishes and treatments collected by the researchers, and some polishes contain it even when they say they don't. (Clear polishes usually contain more TPHP than colored ones.) Separate studies show that women process more of it than men, which points to the idea that they might be absorbing it through beauty products. 

The researchers, who published their results in the journal Environment International, tested the urine of 26 participants before and after they painted their nails with a polish that contained 1 percent TPHP. Two to six hours after painting their nails, 24 of the participants had slightly elevated levels of diphenyl phosphate, or DPHP, a chemical that indicates TPHP has been processed in the body. And 10 to 14 hours after painting the nails, every single participant had DPHP levels increase by nearly seven times. Participants who wore gloves to apply the polish to synthetic nails didn't have any difference in DPHP levels. 

The Environment Working Group has launched a petition asking nail polish companies to remove TPHP from its products, and has published a database of the brands that contain TPHP as an ingredient on its website. Study co-author Kate Hoffman told Yahoo that if you must use polish, avoid getting it on your skin to keep it from absorbing into your bloodstream.

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Megan Friedman

Megan Friedman is the former managing editor of the Newsroom at Hearst. She's worked at NBC and Time, and is a graduate of Northwestern's Medill School of Journalism.