Like millions of other women, I have been using gel nail polish for years and love the fact that it leaves my nails super shiny and lasts for weeks. The global gel nail polish market size is expected to be $4.3 billion in 2024, almost half of the total market. The recent news that a key ingredient in gel nail polish, trimethylbenzoyl diphenylphosphine oxide (TPO), was banned in Europe has caused people across the US to question the safety of gel nail polishes and to consider switching to other alternatives.
What is TPO?
TPO is a chemical added to nail polish to help it harden quickly, without affecting its color. When exposed to UV light, TPO splits apart and becomes trapped in the nail polish, “setting” the manicure. That is the reason why salons now have specialized UV lamps. However, only 0.5% to 5% of the TPO remains on the nail after UV exposure.
Are gel polishes safe?
The answer is an unequivocal YES. No ifs, ands, or buts. No reason to look for alternatives. The reason I am so emphatic is a report by the European Union’s Scientific Committee on Consumer Safety (SCCS), a group of expert scientists, who examined the scientific evidence on TPO and concluded that
“TPO is safe when used as a nail modeling product at a maximum 5%.”
However, the EU banned TPO because it uses a “hazard-approach” where any study, in animals or people that show adverse effects, regardless of the dose, exposure, or sex, is banned. It employs the “Precautionary Principle”, where a chemical is barred if it has the potential to cause harm to humans.
The US is fundamentally different from the EU, using a “risk-based” approach where we examine the risk, considering the dose or concentration tested, type of exposure, and likelihood that people are exposed.
The EU classified TPO as a Class 1B Reproductive Toxin based on the results of two animal studies, even though there is no evidence that it harms people. The absurdity of the EU’s outcome is that the only adverse effects noted in studies were on the testicles of male rats, for a product used almost exclusively by females.
Looking at the Evidence
It is unusual for a country to ban a chemical after a risk assessment done by scientists in their own country has determined it to be safe. But that is the case with TPO. The SCCS report examined all relevant studies in humans and animals.
The only human studies considered the potential to cause irritation or allergic reactions, where no irritation was reported.
The animal studies found TPO had very low toxicity; the only effects were in two studies in rats, where they found “shrinkage” of the testicles. [1]
The scientists calculated TPO’s Margin of Safety, a comparison of the safe level of a chemical, in this case, the concentration of TPO at which no effects were observed in the rats, to the exposure, or the amount of chemical present in the gel nail polish.
The scientists assumed 100% absorption of TPO through the nail plate, even though the actual absorption is much less. They found a Margin of Safety of 1,515 – the safe level of TPO is over a thousand times above the exposure level.
With a safety cushion this high, you do not need to worry about putting on gel nail polish.
Keep Painting Your Nails
You should worry about using gel nail polish if:
- You drink your gel nail polish. The TPO exposure for the rats was through a stomach tube, “mimicking” oral exposure. No researcher took the time to put nail polish on their tiny toes.
- You paint every inch of your body in nail polish. Effects on the testicles were only seen at the highest concentrations in rats, way above any concentrations in nail polish.
Regulators Gone Wild
The lesson that should be learned is that the “Precautionary Principle” is fundamentally flawed because it does not allow for common sense. In this case, common sense tells us that without testicles, you needn’t worry, and even if you do, you have a safety cushion of over a thousand.
A US risk assessment would have concluded that the risk from TPO is almost non-existent, and we could move on to risks that really matter. The EU’s approach raises uncertainty and unwarranted concern. I know the Europeans love a good protest. Women should take to the streets, demanding their rights to a beautiful gel nail polish.
[1] Usually, I look at the toxicology studies to assess their quality. This was not possible because they were not published in the report.
