Pretty Deadly Nails – What’s in Your Nail Polish?


Giselle Henderson »

Dating as far back as 3000 B.C., the common practice of decorating fingernails and toenails is one enjoyed by many women worldwide. (1) It is common for women to maintain a strict weekly ritual of painting their own nails or going to a salon for a pampering manicure or pedicure. Nowadays women (as well as men, children and even dogs) enjoy a wide range of options when it comes to their nails, from a classic red shade or a French manicure to the latest constantly-evolving and sometimes wacky trends. Most recently, people have been taking full advantage of social media not only to set and emulate these trends with uploaded photos and tutorials, but also to elevate nail art to just that, a true form of art, inspiring endless creative ideas for how to fill the canvas that is the fingernail. Nail polish, also known as nail varnish or lacquer, comes in a vast array of colors and textures, and there are just as many styles, techniques and types of manicures, with formulas constantly being updated in order to last longer and be more resistant to chipping. But while factors such as durability and texture are common considerations for many people when choosing a nail polish formula, how often do we think about what exactly is in this stuff we are painting on our bodies so often? Also – and perhaps more important than setting or following the latest trend – could the ingredients have a negative impact on our health?

Despite the fact that most people are taught from a young age by their parents and teachers not to intentionally inhale strong fumes like nail polish, many of us actually enjoy its smell. We certainly have good reason to avoid inhaling toxic fumes, but other than this word of caution, using nail polish as intended is generally not thought to be dangerous to human health (especially in comparison with other personal care products that in recent years have come under scrutiny for the safety of their ingredients). There are several reasons why nail polish has remained largely exempt from this debate until recently. First, most people assume that in developed countries cosmetics must have to go through rigorous testing for health and safety, like food products, before going on the market, which is not the case. In fact, the cosmetics industry is mostly unregulated; despite the fact that the Food and Drug Agency in the U.S. has the authority to ban cosmetic ingredients, it does not actually do so. Of the over 13,000 chemicals used in cosmetics, only about 10% have been tested for safety. (2) Second, most people would not assume that nail polish would be able to enter our bodies at all. After all, the keratin in our nails makes them incredibly strong and impermeable. Third, beyond the perceived beauty of painted nails by most cultures, nail polish can offer distinct benefits. Some special nail polish formulas are proven to strengthen weak nails prone to breakage, which can reduce the risk of hangnails and infections, while others can help people who bite their nails overcome this habit by deterring them with its bitter taste.

The Basic Formula

So, is nail polish safe? To answer this complex question, we must first explore in detail the ingredients of nail polish and their functions. The chemicals used vary depending on the type of polish, however the basic formulation is a film-forming polymer dissolved in an organic solvent. The most common formula is nitrocellulose, C6H7(NO2)3O5 , dissolved in butyl acetate or ethyl acetate. (1). Nitrocellulose is formed by nitrating cellulose (exposing it to nitric acid or other nitrating agent), and was originally used as an explosive and known as “gun cotton.” Nitric acid is used to convert cellulose into cellulose nitrate and water: (3)


3HNO3+ C6H10O5 → C6H7(NO2)3O5 + 3H2O

The “Toxic Trio”

Known as the toxic trio, Formaldehyde, toluene, and dibutyl phthalate (DBP) are three ingredients often found in nail polish. Formaldehyde is a preservative, stabilizer and embalmer that in nail polish is found as tosylamide-formaldehyde resin, C8H11NO3S, an adhesive polymer that alters the nitrocellulose by making it tougher and less brittle, and provides a glossy finish. This resin is often used in base and top coats to strengthen the nail and to help the main polish adhere to the nail and last longer. The International Agency for Research on Cancer considers formaldehyde to be a carcinogen, linking it to lung and nasal cancers. While the resin has not been linked to cancer, it may contain residual levels of formaldehyde. (4, 5, 6) Additionally, formaldehyde resin is a skin allergen known to cause dermatitis.

Toluene, C7H8, is a clear colorless liquid with a characteristically strong odor, used as a solvent which is added to nail polish to give it a smooth, even finish. Exposure to elevated airborne levels of toluene, resulting in symptoms such as dizziness, nausea, headache, and irritation of the eyes and upper respiratory tract (7) Chronic exposure to toluene has been linked to anemia, lowered blood cell count, and liver or kidney damage. (2). Toluene toxicity may also affect a developing fetus, linked to birth defects and developmental problems in women who were exposed to the chemical during pregnancy (6)

Dibutyl phthalate, C16H22O4 or DBP, is a plasticizer used in nail polish to make it shinier, more flexible and more resistant to cracks and chips, a common irritation for the nail polish wearer. (8) Along with other phthalates, a category of well-established endocrine disrupting substances, DBP is a carcinogen and mutagen linked to lifelong reproductive abnormalities in male rats. It is found at the highest levels in women of childbearing age, putting any children born to these women at considerable risk for reproductive defects during sensitive and critical developmental periods. (2) Fortunately, both DBP and toluene have been banned in the European Union, but neither has in the United States. (6) Many companies pledged to remove the “toxic trio” ingredients as long ago as 2006. However, in 2012, the Department of Toxic Substances in California tested these supposedly new and improved polishes and found that some products still contained them even though they were marketed as “three free.” In fact: 10 out of 12 nail polishes claiming to be free of toluene contained it; and 5 of 7 nail polishes that claimed to be free of all three chemicals actually contained one or more at elevated levels. (9)




Another important ingredient currently found in many brands of nail polish is triphenyl phosphate, C18H15O4P, referred to as either TPHP or TPP. This chemical compound is meant to replace DBP, as another plasticizer which is commonly used both in plastics and as a fire retardant. (10) It is added to nail polish to make it more flexible and durable, and clear nail polishes tend to have more TPHP than colored ones. There is a growing body of evidence concluding that it disrupts the human endocrine system, and in animal studies, TPHP exposure caused reproductive and developmental issues. Some recent studies suggest that TPHP interacts with the protein responsible for the regulation of metabolism and production of fat cells, suggesting that is could contribute to weight gain and obesity. (11)


TPHP in nail polish, and also in the body

Urine tests have revealed that Americans are widely exposed to TPHP, most likely due to how frequently it is used as a fire retardant in household furniture. A recent biomonitoring study that investigated TPHP exposure discovered significantly higher levels in women than in men. These findings imply that women could be exposed to more of the chemical due to the use of cosmetics, including nail polish. This idea prompted an October 2015 joint study, from researchers at Duke University and the Environmental Working Group, which revealed some troubling findings. They found TPHP in the bodies of all of the women who had volunteered to paint their nails with polishes containing it. When the participants wore gloves and applied polish to synthetic nails, the urine levels of diphenyl phosphate, or DPHP, the metabolized form of TPHP, did not change appreciably. When women painted their own natural nails, the levels in 24 out of the 26 women rose slightly after two to six hours. However, 10 to 14 hours afterwards, the DPHP levels in all 26 participants had risen by an average of nearly sevenfold, and for three of the four volunteers whose urine was collected over the course of 48 hours, their DPHP levels peaked between 10 and 20 hours after painting their nails. Previous research has proved that molecules normally do not permeate nails; researchers on this latest study have postulated that the solvents in nail polish have an effect on nails that makes them more permeable. They also believe that chemicals likely enter the body through the capillaries found in the cuticle around the nail. (11)

TPHP is listed as an ingredient in the labels for many brands currently on the market. In fact, 49% of over 3,000 nail polishes and formulas in EWG´s Skin Deep cosmetics database disclose that they contain it. However, some polishes do contain it but not include it on their ingredients list. The researchers of the October 2015 study had tested ten different nail polishes for TPHP, and found it in eight of them. Two of these eight did not disclose TPHP as an ingredient. Kate Hoffman, one of the Duke University researchers, cautions “TPHP could be difficult to avoid in nail polish. We think our findings may underestimate the number of nail polishes that it’s in.” (12) The concentrations of TPHP ranged from 0.49 percent and 1.68 percent by weight. The nail polish used in the study contained about 1 percent TPHP.

Implications for the future

Even when cosmetics or personal care chemical ingredients are found to be dangerous in lab studies, it is often claimed, especially by industries that represent them, that the amount that most people are exposed to is too small to have a significant impact. However, this study, though of an admittedly small sample size, reveals that nail polish may be a significant source of short-term TPHP exposure, which for frequent nail polish users translates into long-term exposure and the risks that carries. Other users of particular concern are pregnant women and women of childbearing age, children, and people who bite their nails and therefore may ingest the chemical. Another critical group to consider are those who work in nail salons; although many wear masks to avoid breathing in substances directly, and some salons are equipped with ventilation systems, workers are still at a high risk of inhalation of not only the chemicals used in polishes and treatments, but also toxic acrylic dust from the filing and cutting of synthetic nails.

In a broader sense, it is important to keep in mind as research findings such as these add up, that nail polish is just one of many personal care and household products containing small amounts of a range of toxic chemicals that we are indeed taking into our bodies in one way or another, every single day of our lives. Therefore, the cumulative effect of chronic exposure to all of these toxic chemicals added up is what must be evaluated more seriously and objectively by regulatory agencies, especially in the United States where the toxic trio are neither banned nor restricted. Stricter sanctions for brands that do not disclose all of their ingredients, and bans on ingredients proven to be harmful are only a first step. Johanna Congleton, a senior scientist at EWG who worked on the October 2015 study, says their findings highlight this need for better regulation of cosmetics. “We shouldn’t be in this situation,” she warns. “We need to make sure we have a clear picture of the safety data before these compounds wind up in products and people’s bodies.” (12) EWG urges for the U.S. Congress to enact legislation to update laws regarding chemicals and cosmetics, by requiring chemicals to present “reasonable certainty of no harm.” (13)

In summary, it is clear that more research and regulation is needed, but in the meantime there are certain precautions that can and should be taken in order to prevent our intake of toxic ingredients as much as possible. Nail polish users are warned to apply it in well-ventilated areas, to be sure to avoid painting the skin or cuticle area around the nail, and not to bite polished nails. The EWG’s Skin Deep database contains over 3,000 nail polishes that have been evaluated, tested and rated according to the safety of their ingredients. Refusing to buy those brands that contain toxic ingredients is how consumers can “vote with their dollar” and pressure manufacturers to create safer products until laws catch up with the scientific findings. By following this advice and choosing nail polish critically, people will be able to continue to express themselves through the art on their nails – without risking their health at the same time.



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