The mani-pedi is often considered one of life’s simple pleasures—but depending on the polish you’re using, those feel-good vibes can be dampened by a glance at the ingredient label. That’s because nail polishes can contain compounds that have been associated with health problems like birth defects, thyroid dysfunction, obesity, cancer, and allergic reactions. Many products tout the fact that they’re “free” of several of these compounds—but a new study suggests that those labels can be misleading, and that the chemicals they do contain may not be any safer.
The study, published today in Environmental Science and Technology, examines the common practice of nail polish manufacturers labeling their products as “3-free,” which means they don’t contain dibutyl phthalate (DnBP), toluene, and formaldehyde. This practice started more than a decade ago, after these ingredients were strongly linked to reproductive problems, neurological and developmental problems, and cancer.
Since then, however, companies have gone even farther: Many now label their polishes as “5-free,” which means that in addition to the aforementioned “toxic trio,” their formulas are also free of the potential allergens camphor and formaldehyde resin.
Others claim that their polishes are “6-free,” “7-free,” “8-free,” all the way up to “13-free.” And that’s where things start to get confusing, says the study’s first author, Anna Young, a doctoral student at the Harvard T. H. Chan School of Public Health. Because even though one might think that a higher number means a healthier product, she says, that’s not always the case.
For the study, Young and her colleagues looked at 55 polishes across 44 popular brands sold in stores and nail salons. They compared labels and ingredient lists of these products, checking to see how each one defined its claims of being “free” from toxic ingredients. Most of the products labeled 3-free and 5-free were consistent in what was excluded. But as the number rose, the definition of what that number meant became inconsistent.
Out of the 10 products labeled “10-free,” for example, there were six different variations as to what those 10 toxic compounds were. And because there’s no standardization across products, there’s no way to know if a certain ingredient (like lead or acetone or parabens, for example) is included in a product’s list of exclusions. To complicate matters further, some brands’ exclusion lists included things like gluten, wheat, fat, and "animal-derived ingredients," which don’t pose a health threat to most consumers.
In other words, says Young, more exclusions doesn’t necessarily mean a product is any safer or healthier—even though, on average, those with more than three exclusions were priced significantly higher. And to really understand what any of those numbers mean, it’s likely to take some digging on the consumer’s part.
There’s another issue to consider, as well: Even when brands phase out harmful ingredients like DnBP, they’re often replaced with similar compounds that haven’t been studied as much. Scientists worry, and some research does suggest, that these new compounds may not be any better for consumers than their predecessors.
“It’s a practice known as regrettable substitution, and it doesn’t just happen in the nail polish industry,” says Young. (It’s also been reported in the manufacturing of plastic bottles and tin cans, , and pesticides.) “When one toxic ingredient is simply replaced with another one, it’s kind of like playing a game of chemical whack-a-mole.”
The good news is that by now, most brands have phased out DnBP and are reducing the amount of a similar plasticizer (and suspected endocrine disruptor) called triphenyl phosphate (TPHP). But the authors of the new study argue that brands should be doing more to exclude entire classes of ingredients—like or organophosphates as a whole—rather than individual compounds, one at a time. “Then, certified labels could be useful tools for educating nail polish users, nail salon owners, and nail salon workers about toxic chemicals and how to make best purchasing decisions,” they write.
In the meantime, says Young, shoppers can make smarter decisions by reading the full ingredient labels, rather than a marketing gimmick on the front of the package. Consumers should also know that just because one toxic ingredient has been removed, that doesn’t mean there still aren’t risks associated with others.
“Wearing nail polish is a personal choice, and this study isn’t really about what any one person does,” says Young. “What it does highlight is that this is a public health issue that affects not only consumers, but also hundreds of thousands of nail workers who are exposed to these chemicals on a daily basis.”
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