Understanding TPO, HEMA, and Safer Nail Lacquer Choices

When it comes to nail enhancements and long-lasting manicures, the ingredients matter—not just for performance (shine, wear, cure time) but for health. Two ingredients that have increasingly drawn attention in gel and UV nail products are TPO and HEMA. Alongside the well-known “toxic ten,” it’s more important than ever to know what you’re using, how it works, and what risks may come with misuse.

What is TPO (Trimethylbenzoyl Diphenylphosphine Oxide)?

TPO is a photoinitiator: a chemical that absorbs UV (or LED) light and starts the polymerization reaction that “cures” or hardens gel/UV nail products. It’s effective, fairly common in gel topcoats/base layers/builders, and valued for its ability to cure well under certain lamps, often with less yellowing than older photoinitiators.

Potential Side Effects / Safety Concerns of TPO

Although TPO has been used for years, recent research, particularly by EU bodies, has highlighted concerns, especially with non-typical or excessive exposures. Key possible side effects include:

• Reproductive toxicity: Animal studies have found adverse effects on male fertility (testicular atrophy, reduced testes weight, problems with spermiogenesis) at high oral doses.

• Liver and kidney damage: Repeated, high-dose exposure in animals has shown increases in liver and kidney weight, changes in biochemical markers, and histological changes.

• Skin irritation and sensitization: TPO can irritate skin or eyes; in animal/mouse tests there is moderate sensitizing potential. Contact through the cuticle or sidewalls of the natural nail is especially risky if uncured or improperly cured.

• Mutagenicity / Genotoxicity concerns (ongoing): Some studies flagged potential for DNA damage under certain conditions, especially with high doses or improper curing. However, human data is limited.

• Exposure risk for technicians: Regular handling may increase the risk of skin contact or inhalation, especially if safety measures like gloves and ventilation are lacking.

In practice, for properly formulated, cured nail gel applications where TPO is used in low concentrations, exposure (especially systemic) is likely much lower than the levels in animal studies. But the potential for risk under misuse or over-exposure is what drove regulatory scrutiny.

What is HEMA (2-Hydroxyethyl Methacrylate)?

HEMA is a monomer used in many nail gels, acrylics, and adhesives. It improves adhesion and flexibility, helping the product binder adhere to the natural nail.

Potential Side Effects / Safety Concerns of HEMA

• Allergic contact dermatitis: one of the most commonly reported issues. Redness, swelling, blistering, itching around cuticle, nail fold, or adjacent skin.

• Cross-reactivity: once someone becomes sensitized to HEMA or related methacrylates, they may react to many similar chemicals, making many nail products, adhesives, or even dental/medical materials problematic.

• Nail plate damage/separation: overuse or misapplication can lead to lifting, thinning, or even splitting as the chemical penetrates or the adhesive properties are mismanaged.

• Skin penetration and systemic concerns: because HEMA is a small molecule, it penetrates better through skin (and possibly through nail plate) if improperly applied or left uncured.

The “Toxic Ten” in Nail Lacquers

These are ingredients often flagged as harmful (to varying degrees) that many “clean nail” brands avoid. The classic “toxic ten” often includes:

1. Formaldehyde

2. Toluene

3. Dibutyl Phthalate (DBP)

4. Camphor

5. Formaldehyde resin

6. Ethyl Tosylamide

7. Xylene

8. Triphenyl Phosphate (TPHP)

9. Parabens

10. Fragrances

Brands that are “10-free” commit to excluding all of them. Some go further (e.g. “15-free” etc.), but “10-free” is a well-recognized baseline for safer nail products.

Why the EU Decided to Ban TPO & What It Means?

The animal studies evaluated included high-dose oral administration of TPO in rats, which showed negative reproductive outcomes for males which is why the EU has classified it as CMR category 1B because there is enough evidence to consider it a reproductive toxicant under regulation.

However, there is debate in the industry and some scientific commentary about the relevance of those animal exposure conditions vs. real-world exposure via cured gel on nails. Some arguments say that once cured, much of the TPO is consumed or locked in the polymer, reducing systemic exposure. But regulators typically assume potential worst-case / margin of safety scenarios.

Key Takeaways

• Both TPO and HEMA serve crucial functional roles in gel/UV nail lacquers (curing, adhesion, durability), but they also have potential risks, especially under improper use, overexposure, or for people with sensitivities.

• TPO has been recently banned in the EU (from September 1, 2025) due to reproductive toxicity concerns; the U.S. has not banned it but may see voluntary reformulations.

• “10-free” status remains an important marker of avoiding many chemicals with known or suspected health harms.

• Proper formulation, correct curing, minimal contact with skin, and quality control are key to reducing risk.

• Anything labelled “TPO-free,” “HEMA-free,” and “10-free” is a strong indicator of safer product choices, especially in professional settings.

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Frequently Asked Questions About TPO

Why did the EU ban TPO but it’s still legal in the U.S.?

Because the EU uses a hazard-based approach: once there's credible evidence that a substance is carcinogenic, mutagenic, or toxic for reproduction, it can be banned even if everyday exposure hasn’t been shown conclusively harmful in humans. The U.S. focuses more on risk-based regulation—how much exposure people actually get, and whether that level poses danger.

Does the EU ban mean that any gel polish with TPO used before September 2025 is unsafe?

Not automatically. The concern is about continued manufacture, sale, and use in the EU. Existing cured gels, especially those correctly applied, may pose very low risk. But from September 1, 2025, products containing TPO cannot be legally sold or supplied in the EU.

Can someone reverse a sensitivity to HEMA or TPO?

With HEMA, once sensitization (an allergic reaction) has occurred, avoiding future exposure is the standard approach; it's difficult to “reverse” the allergy. For TPO, most issues are not classical allergies but toxicity at high doses, so the risk is more about reducing exposure rather than “allergy” per se. If someone has a skin reaction, a board-certified dermatologist should evaluate.

Do 10-free and TPO-free polishes perform worse?

Not necessarily. Many brands are investing in safer alternatives (different photoinitiators, monomers, resins) that deliver similar durability, shine, and wear time. The biggest challenges are curing protocols and product formulation. If those are done well, performance can be excellent.

What should I do if I'm concerned about TPO & HEMA?

• Ask your nail tech what ingredients they’re using (look for TPO, HEMA, or any of the toxic ten).

• Ensure proper curing times and correct equipment.

• Request minimal skin/sidewall exposure; avoid contact with cuticles.

• Consider using gloves or barrier creams if you are sensitive or often getting gels/polish.

• Monitor for any signs of irritation or allergic reaction (itching, redness, swelling, blistering) and stop use/seek medical advice if they occur.

Our Studio Assurance

All lacquers and gel/UV products used in my studio are TPO-free, HEMA-free, and 10-free, meaning I go above and beyond minimal safety expectations. As always, your nails are treated not only for beauty and durability, but also health. Ready for a stunning set of nails, book your appointment today!