By Maya Attal, Staff Writer
You sit down to pick a color, pink in the summer, bordeaux in the winter, and one hour later, you walk out with perfectly polished, glossy nails. In fact, come around the holidays, it seems like almost every girl has one thing in common: her nails are done.
It seems pretty harmless. After all, it is just a manicure, a small ritual that makes you feel more put-together and for many of us more confident.
But how harmless is it really?
The answer to this question lies in a complex mix of biology, chemistry and infectious disease studies.
While early forms of nail polish were made of completely natural ingredients such as beeswax, egg whites, gelatin and crushed flower petals for color, today’s recipe has vastly evolved. It now contains ingredients with names you probably have never even heard of before and can’t even pronounce: trimethylbenzoyl diphenylphosphine oxide, nitrocellulose, tosylamide Formaldehyde Resin, and many more.
Some of these ingredients need more attention than others, such as formaldehyde and other formaldehyde-releasing ingredients. These are known to help harden nails or improve the durability of the polish. Nails, hair and our epidermis are all made of keratin, a tough, fibrous structural protein chain. Formaldehyde is a highly reactive aldehyde that can react with the amino groups in proteins to form covalent cross-links between protein molecules. These cross-links make the whole keratin network tighter, hardening the nail.
The problem is that formaldehyde is also a known irritant and carcinogen at sufficiently high exposures. In a 1980 Cancer Research Study, scientists exposed rats to formaldehyde vapor for 6 hours a day for over 5 days a week at concentrations of 0, 2, 6 or 15 ppm. After 18 months, 36 rats exposed to 15 ppm had developed carcinomas in the nasal cavity while none of the lower-exposure groups developed tumors.
While this study undeniably shows that formaldehyde can be carcinogenic at high exposure, it also shows that toxicology depends on concentration and frequency. Indeed, none of the rats exposed to the lower ppm of formaldehyde developed carcinomas. In the case of nail polish, not only is the exposure limited but it is also not inhaled in the same way that the rats were exposed to formaldehyde which evidently reduces the risk of carcinoma. But formaldehyde is not the only source of toxic exposure, as once the polish is applied, a new process is introduced: ultraviolet radiation.
To make the polish last, it is cured under a UV lamp. These devices emit UVA radiation, which penetrates the skin more deeply than UVB. In 2023, researchers from the University of California San Diego and the University of Pittsburgh reported that radiation from UV nail dryers could cause DNA damage and mutations in cultured cells.
Our DNA is made up of four different nucleotide bases known as adenine (A), thymine (T), cytosine (C), and guanine (G). Normally, adenine pairs up with thymine while cytosine pairs up with guanine. However, UVA can generate reactive oxygen species inside cells which can oxidize guanine and turn it into its damaged form called 8-oxo-dG. During DNA replication, the damaged guanine gets paired incorrectly with adenine producing a characteristic C → A mutation. This small difference can potentially alter proteins, disrupt cell function, and contribute to cancer if specific genes are affected.
But perhaps the most overlooked risk in a manicure has nothing to do with the nail polish itself or the UV lamp; rather, it comes from the cuticle cutter that comes in contact with your skin.
The purpose of this tool is specifically to remove dead and unwanted excess skin. Unfortunately, every once in a while, a nail technician can accidentally create a tiny painless cut in the skin that seems completely harmless.
The problem arises if the same cuticle instrument previously in contact with someone else’s blood has not been properly sterilized. If that contaminated instrument then breaks the skin, bloodborne pathogens can easily enter the bloodstream. HIV transmission risks remain low since the virus survives poorly outside the body as its infectious virus levels drop dramatically within a few hours. Hepatitis B and C, however, are a bigger concern.
Hepatitis B in particular is considerably more transmissible than HIV. Studies show that hepatitis B remains capable of causing infection on surfaces for at least a week, giving it more than enough time to be transferred if a nail tool is reused on another client without proper sterilization. Studies of contaminated needlestick injuries estimate the risk of infection at approximately 6–30% for HBV, 1.8% for HCV and 0.3% for HIV in susceptible individuals.
So, after all of this, should we throw away our nail polish, cancel every gel appointment, and never let anyone touch our cuticles again?
Probably not.
While a manicure involves real risks, exposure does not automatically mean significant health hazards as it all depends on dose, duration, frequency, route of exposure and safety precautions.
And interestingly, the concern about manicures arose a long time ago in the Talmud. In Niddah 17a, we are warned against leaving fingernail clippings where a pregnant woman might step on them, associating this with the risk of miscarriage. The issue at hand is obviously very different, the Talmud was not describing formaldehyde toxicity or viral transmission, yet it is fascinating that, centuries before, Jewish tradition was already paying attention to the potential dangers associated with an insignificant discarded fingernail.
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