Essie, OPI, Sally... say it isn’t so!
Triphenyl phosphate is a suspected endocrine-disrupting chemical that is used in plastics manufacturing and as a fire retardant in foam furniture. A growing body of evidence indicates that TPHP causes endocrine disruption, which means it interferes with hormone functioning. In animal studies, it has been shown to cause reproductive and developmental irregularities.
According to a study by researchers at Duke University and Environmental Working Group, TPHP — also known as TPP — was found in all the women who painted their nails for the study.
Of more than 3,000 nail polishes and treatments compiled in EWG’s Skin Deep database, 49 percent disclose that they contain TPHP. Some polishes include it but do not put it on their ingredient listings.
The study, which was published in Environment International, tested only 10 nail polishes for TPHP. The chemical was found in eight of the products, and two of the polishes that had TPHP in them did not disclose the chemical’s existence on their labels (though the study did not disclose which polishes these were).
Johanna Congleton, Ph.D., MSPH, a senior scientist at EWG and co-author of the Duke-EWG study, said the study was conducted on 26 participants.
In the study, researchers found that participants' diphenyl phosphate, or DPHP, levels, which is a biomarker created when the body metabolizes TPHP, went up when they applied the polish to their nails. The women's urine was tested for DPHP 24 hours before nail polish was applied and a few times after.
Two to six hours after they painted their nails, 24 of the 26 volunteers in the study had slightly elevated levels of DPHP in their urine. Ten to 14 hours after polishing their nails, the DPHP levels in all 26 participants had risen by an average of nearly sevenfold, suggesting that the longer the nail polish sat, the more TPHP entered their bodies and metabolized into DPHP.
Four volunteers collected urine over 48 hours. In 3 out of the 4 cases, concentrations of DPHP peaked between 10 and 20 hours after painting their nails.
In addition to painting their natural nails, they also put on gloves with synthetic nails attached to them. Levels were not detected on the fake nails or gloves. Inhalation didn’t seem to be a significant pathway to exposure.
“We know from biomonitoring data from a number of studies… that people are widely exposed to this compound,” Congleton said. “We know now that nail polish can be a sign source of exposure in the short term, and long term for people who apply nail polish frequently.”
Why is this stuff in nail polish at all? The manufacturers likely added TPHP as a plasticizer to make the polishes more flexible and durable after reports surfaced that dibutyl phthalate, or DBP, and other phthalates are likely endocrine disruptors that can be toxic to the reproductive system.
Clear polishes are the biggest TPHP culprits — researchers found they contained more TPHP than colored polishes did.
Scientists say that most molecules do not permeate actual nails, but instead believe that capillaries in the cuticles may be responsible or have a role in the body’s absorption of the chemical.
Most studies on TPHP have examined its effects on cells and test animals. A few studies have linked TPHP with changes in the hormone and reproductive systems of humans. Recent studies suggest that TPHP interacts with a protein central to regulating the body’s metabolism and production of fat cells. Scientists are looking into whether or not TPHP contributes to weight gain and obesity.
Women could be more at risk for TPHP exposure too. A recent biomonitoring study by Duke scientists who investigated TPHP exposure in adults found significantly higher levels of DPHP in women than in men who were tested in a separate study. These findings suggest that women may absorb more TPHP through personal care products, such as nail polish, that are marketed specifically to women.
Another biomonitoring study conducted last year by Duke and EWG researchers found DPHP, the metabolite of TPHP, in the urine of 95 percent of the adults and 100 percent of the children who participated. A separate study by scientists from Duke University and the University of North Carolina found DPHP in more than 90 percent of samples collected from pregnant women. Further, an Australian study found DPHP in more than 95 percent of samples tested, and researchers in Asia found TPHP in 86 percent of breast milk samples from Japan, the Philippines and Vietnam.
Read the labels to see if this compound is in your polish. Sometimes a seller’s display will have ingredients if there are too many to list on the bottle.
“It really points to the broader issue that we need better testing information and safety information on chemicals in general,” Congleton said. “We really need a system that ensures ingredients in products that we use every day… or just in general... are safe.”
In a statement from Beth Lange, chief scientist at the Personal Care Products Council, she slammed the study.
"American consumers should not be concerned by new research that is speculative, misleading and does not use sound science to assess the safety of an ingredient which has a long and well documented history of safe use," Lange said.
“Clearly, there is no substance behind these alarming claims. The makers of nail polish stand behind their products and take pride in providing Americans with access to a wide variety of safe high quality and innovative products they trust and enjoy," she added.
Want to take action and urge manufacturers to stop using TPHP? Complete the petition here.
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