As we’ve reported before, it’s hard, if not impossible, to know exactly what’s in cosmetics and whether they are safe. Nail polish is no exception. In particular, nail polish contains plasticizers to make it flexible and chip-resistant, but as endocrine disruptors, these chemicals—which can be absorbed into skin or inhaled—may adversely affect reproductive health, fetal development, and thyroid function.
It’s not known what level of exposure is a significant health risk, but a study in 2000 found that women of childbearing age had higher urine levels of di-n-butyl phthalate (DnBP), a plasticizer used mainly in nail products, than men and other age groups. A 2014 study linked DnBP exposure during pregnancy to lower IQ in children at age seven.
Over the past two decades, U.S. nail polish manufacturers have largely eliminated DnBP (which was banned in Europe in 2004), along with some other ingredients of known risk, such as toluene and formaldehyde. They are also increasingly labeling their products as nontoxic or “n-free,” where the “n” refers to the number of problematic ingredients supposedly removed (such as in “3-Free” or “5-Free”). But as a study published in late 2018 in Environmental Science & Technology warns, there are no uniform standards for such labeling, and the substitute ingredients may be just as toxic.
For instance, in a case of what is called “regrettable substitution” in public health, some nail polishes contain triphenyl phosphate (TPHP) in place of DnBP, even though this ingredient has more recently been recognized as another endocrine disruptor. “Regrettable substitution can occur because the U.S. lacks a regulatory structure to motivate proactive consideration of health risks of replacement chemicals,” the study noted.
Moreover, with the exception of color additives, nail polish manufacturers do not have to do safety testing. Nor do labels—either on the bottles or in Safety Data Sheets provided to salons—have to disclose all the ingredients, due to various labeling loopholes.
Among some other plasticizers that may be found in nail polishes are ethyl tosylamide, propylene glycol, propylene carbonate, dipropylene glycol dibenzoate, and camphor. Some plasticizers may simply be labeled as “fragrances.”
Toxic ingredients, confusing labels
The recent study looked at the labels and ingredients of nail polishes and tested 40 of them from 12 different brands for a variety of plasticizers to see how well the label claims aligned with what was really in the products. Red and pink shades, as well as different finishes (shimmer, metallic, glitter), were tested by the researchers. Here are some takeaways:
- The nail polishes were found to contain 13 of 22 plasticizers tested for, at varying levels. None had detectable DnBP—and levels of TPHP were lower than previously reported (good news). However, some products without TPHP were found to have higher levels of DEHP, which is yet another endocrine disruptor and possible carcinogen that has been banned in Europe.
- Generally, the only label that has uniform meaning is “3-Free,” which was introduced in the 2000s and indicates that the polish is free of the “toxic trio”: DnBP, toluene, and formaldehyde. Newer labels claim to be anywhere from “4-Free” to “13-Free.” Most common is a “5-free” label, followed by “10-Free.” Of note, the definitions of the labels—that is, which ingredients are specifically being referred to—vary by product line.
- A higher-numbered label, such as “10-Free,” does not necessarily indicate a polish with fewer toxic ingredients than one with a lower number. That’s because some of these excluded ingredients may be nontoxic ones. “Thus, the expanded labels can cause confusion about the meaning of the labels, which originally intended to denote the number of toxic nail polish ingredients removed,” the researchers pointed out.
- Brands with higher numbered labels (above “3-Free”) cost significantly more per fluid ounce, suggesting that listing more exclusions is being done to command higher prices.
- The study did not include increasingly popular gel polishes, which have different formulations than regular nail polishes.
Bottom line: Nail polish is undoubtedly an occupational hazard for salon workers. But many women apply it themselves several times a month (some daily), thus increasing their exposure to plasticizers and other potentially harmful chemicals. Nail polish companies should reformulate their products with fewer or none of these ingredients, and there should be uniform standards and independent certification for labels. In the meantime, the Environmental Working Group (EWG) provides some guidance for choosing safer nail polishes at its Skin Deep Cosmetics Database. You can also download EWG’s app for iPhones and Android devices.