Ingredient Regulation Guide

HEMA, HPMA & TPO in nail products: what the EU and US actually allow

A plain-language, citable reference to the methacrylate-era ingredients every gel brand is now judged on - who sets the rules, what's banned, what's restricted, the permitted levels, the TPO-substitute question, and how to stay compliant.

Published by Nailspiracy Reviewed June 2026 Reading time ~13 min Scope EU & United States

Luxury scientific nail product regulation visual

Key facts at a glance

HEMA (CAS 868-77-9) is restricted, not prohibited, in the EU. Since 3 June 2021 it may only be used in professional nail products, which must be labelled "For professional use only" and "Can cause an allergic reaction" (Regulation (EU) 2020/1682).
TPO (CAS 75980-60-8) is prohibited in EU cosmetics from 1 September 2025 after being classified as a reproductive toxicant (CMR 1B). No safe level applies; it must be removed from the EU market.
TMO (common TPO replacement, CAS 270586-78-2) is a different substance. SCCS safety assessments support use levels around 5% in nail products, though this is not a formal legal concentration cap.
HPMA (CAS 27813-02-1) is not specifically restricted in either the EU or the US, but it is a recognised methacrylate skin sensitiser - "HEMA-free" does not mean "sensitiser-free."
At the federal level, the United States does not specifically prohibit HEMA, HPMA or TPO in cosmetic nail products. MMA is the major exception - historically targeted by FDA enforcement action and prohibited or restricted by many state boards.
Nailspiracy formulates its gel range without HEMA (868-77-9) and without TPO (75980-60-8), and discloses full CAS-level composition on every Safety Data Sheet.

If you make, sell, or use UV/LED gel products, four ingredients now define whether a formula is compliant, sellable, and safe to market: HEMA, HPMA, TPO and MMA. They are constantly confused with one another, yet each has a different chemistry, a different risk, and a completely different legal status. This guide separates them and states exactly what the European Union and the United States require, as of June 2026.

01The four molecules that matter

All four belong to the methacrylate family, but they are not interchangeable. The single most common compliance mistake in the nail industry is treating "methacrylate" as one thing.

HEMA 2-Hydroxyethyl methacrylate · CAS 868-77-9 EU: restricted US: allowed

The workhorse monomer that gives gel its adhesion. It is a weak-to-moderate skin sensitiser - the leading cause of gel-related allergic contact dermatitis when it touches the skin around the nail. It is restricted in the EU to professional use and permitted in the US.

HPMA Hydroxypropyl methacrylate · CAS 27813-02-1 EU: not restricted US: not restricted

A close chemical cousin of HEMA, often used as a HEMA replacement. It carries the same allergy concern (classified H317 "may cause an allergic skin reaction" and H319) but is not specifically restricted in either the EU or US. A product can be truthfully "HEMA-free" and still contain significant HPMA.

TPO Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide · CAS 75980-60-8 EU: prohibited US: allowed

A photoinitiator - the ingredient that makes gel cure under a lamp. Reclassified as a reproductive toxicant (CMR category 1B), which automatically triggered its prohibition in EU cosmetics from 1 September 2025. It is not specifically prohibited at the US federal level.

MMA Methyl methacrylate · CAS 80-62-6 US: state-restricted EU: not restricted

The old, cheap acrylic monomer associated with nail damage and severe reactions. The US FDA has taken enforcement action against liquid MMA monomer in fingernail preparations and describes it as "poisonous and deleterious"; it is also prohibited or restricted by many state boards. Replaced industry-wide by EMA (ethyl methacrylate).

The takeaway: "free-from" claims are only meaningful when tied to a specific CAS number. "HEMA-free" (868-77-9) and "TPO-free" (75980-60-8) are precise, verifiable claims. "Methacrylate-free" is almost never true of a gel and should be avoided.

02Where the rules come from

Understanding who issues a rule tells you how binding it is and how fast it can change.

European Union

Regulation (EC) No 1223/2009 - the EU Cosmetics Regulation, the master law for every cosmetic sold in the EU. Its Annex II lists prohibited substances; Annex III lists restricted ones.
SCCS (Scientific Committee on Consumer Safety) - the EU's independent scientific panel. It reviews ingredients and publishes opinions that the European Commission turns into law.
ECHA (European Chemicals Agency) - runs the CLP Regulation (EC) No 1272/2008, which assigns hazard classifications (such as the CMR 1B status that doomed TPO).
The European Commission - converts SCCS opinions and CLP classifications into binding "Omnibus" amendments to the Annexes.

United States

FDA, under the Federal Food, Drug, and Cosmetic Act (FD&C Act) and the 2022 MoCRA modernisation - regulates cosmetics, but does not pre-approve cosmetic ingredients and has prohibited very few outright.
CIR (Cosmetic Ingredient Review) - an industry-funded expert panel that publishes safety assessments; influential but not law.
State cosmetology boards - where most state-level nail rules live (for example, MMA prohibitions).
California DTSC - uses the Safer Consumer Products programme to target specific ingredients (it moved on MMA above 1,000 ppm in 2024-2025).

Structural difference: the EU regulates by pre-market substance lists (a substance is allowed only on the terms set in the Annexes), while the US regulates mostly after the fact and largely at state level. This is why an identical gel can be illegal in Berlin and unremarkable in Texas.

03EU regulation in detail

Key EU milestones for nail ingredients, 2021-2026.

HEMA & Di-HEMA TMHDC - restricted (Annex III)

After cases of sensitisation reported in several member states, the SCCS concluded in 2018 that HEMA and Di-HEMA TMHDC are weak-to-moderate sensitisers that are safe only when kept to the nail plate and away from surrounding skin. The Commission acted through Regulation (EU) 2020/1682, adding both to Annex III. The terms:

Permitted in professional nail products only; any other cosmetic use is prohibited.
Two mandatory warnings on pack: "For professional use only" and "Can cause an allergic reaction."
Effective 3 June 2021 (placing on the market) and 3 September 2021 (making available).

There is no numeric percentage cap in the regulation itself. The control is the professional-use restriction plus the warnings, with the product supplied "ready for use." Used under those conditions, HEMA is restricted, not prohibited. (In practice, professional formulations run up to roughly 35% HEMA, but that figure is an industry norm, not a legal ceiling.)

TPO - prohibited (Annex II)

TPO received a harmonised CMR category 1B classification (suspected of damaging fertility/the unborn child). Under the Cosmetics Regulation, a CMR 1B substance is automatically prohibited unless specifically exempted - and no exemption was granted. TPO was added to Annex II by Commission Regulation (EU) 2025/877 (the "Omnibus VII" act), and from 1 September 2025 any cosmetic containing it can no longer be sold in the EU, regardless of concentration or when it was bought. The European Commission has published a dedicated TPO in nail products Q&A confirming that professionals may not use up existing stock after that date.

TPO substitutes and the 5% question

Removing TPO means changing the photoinitiator. One common TPO replacement in professional gels is TMO (Trimethylbenzoyl ditolylphosphine oxide, CAS 270586-78-2) - which is a different substance from the prohibited TPO (75980-60-8). SCCS safety assessments support use levels around 5% in nail products for acylphosphine-oxide photoinitiators of this type, but this is an SCCS reference level, not a formal legal concentration cap.

Two things to watch:

TMO has no harmonised EU classification. That means suppliers self-classify it, and they don't always agree - one factory may label TMO as a suspected reproductive toxicant (H361) while another labels the same substance, at a similar percentage, as not classified. The difference is classification philosophy, not different chemistry.
"TPO-free" only confirms the absence of 75980-60-8. It does not tell you which photoinitiator replaced it or at what level. Always read the SDS for the actual photoinitiator and its percentage.

This is exactly why Nailspiracy states the photoinitiator and its CAS number explicitly on every Safety Data Sheet - so a "TPO-free" claim can be checked against the real formula rather than taken on trust.

HPMA - not specifically restricted

HPMA is not listed in Annex II or Annex III. It is legal in EU consumer and professional nail products with no special labelling. It is, however, a known sensitiser, and brands relying on it as a "HEMA-free" substitute should expect continued scientific scrutiny of the wider methacrylate group.

04US regulation in detail

At the federal level, the United States does not specifically prohibit HEMA, HPMA or TPO in cosmetic nail products. Cosmetic ingredients are not pre-approved, and the FDA's enforcement focuses on misbranding and demonstrable harm rather than ingredient lists.

MMA: the main exception

The FDA has taken enforcement action against liquid MMA monomer in fingernail preparations and describes it as "poisonous and deleterious."
Many state boards prohibit or restrict MMA in nail services; California has prohibited even possession in licensed salons since 1994 (Title 16, §989).
California's DTSC adopted nail products containing MMA above 1,000 ppm as a Priority Product, effective 1 April 2026.
EMA (ethyl methacrylate) is the accepted acrylic monomer in its place.

HEMA, HPMA and TPO in the US

All three remain permitted in US nail products at the federal level. There is no mandatory "professional use only" label for HEMA as there is in the EU, and TPO - prohibited in Europe - can still be sold in the United States. This transatlantic gap matters for any brand selling in both markets: an EU-compliant formula will often be easier to position in the US, but US compliance still requires meeting general cosmetic safety, labelling and business obligations - and a US formula is frequently not EU-compliant.

05EU vs US, side by side

Ingredient	CAS	European Union	United States
HEMA	868-77-9	Restricted	Allowed
Di-HEMA TMHDC	72869-86-4	Restricted	Allowed
HPMA	27813-02-1	Not specifically restricted	Not specifically restricted
TPO	75980-60-8	Prohibited	Allowed
TMO	270586-78-2	Not specifically restricted	Allowed
MMA	80-62-6	Not specifically restricted	State-restricted
EMA	97-63-2	Allowed	Allowed

"Restricted" (EU) = professional-use only with mandatory warnings. TPO is prohibited in the EU from 1 September 2025. TMO has no formal legal cap; SCCS assessments reference around 5%. "State-restricted" = prohibited or restricted by many US state boards.

06Permitted concentrations

"What percentage is allowed?" is one of the most common questions in the nail industry. The answer is often misunderstood because not all ingredient restrictions are based on concentration limits.

In some cases, the law sets a specific prohibition. In others, it restricts how a product may be sold or used rather than defining a maximum percentage.

Regulatory reference levels

Ingredient	CAS Number	European Union	United States
HEMA	868-77-9	No concentration cap. Restricted to professional-use nail products with mandatory warnings.	No federal concentration limit.
HPMA	27813-02-1	No concentration cap. Not specifically restricted.	No federal concentration limit.
TPO	75980-60-8	Prohibited in cosmetic products from 1 September 2025.	No federal concentration limit.
TMO	270586-78-2	No formal legal cap. SCCS assessments support safe use in nail products at approximately 5%.	No federal concentration limit.
MMA	80-62-6	No specific EU nail-product restriction.	Effectively prohibited in professional nail use in many states and heavily restricted by regulators.

Important distinctions

HEMA (868-77-9) is often misunderstood. The EU does not set a maximum percentage for HEMA in nail products. Instead, the ingredient is restricted to professional-use products and requires specific warning statements.

HPMA (27813-02-1) has no specific concentration restriction in either the EU or the United States. However, it remains a recognised methacrylate sensitiser and should not be considered risk-free simply because it is not HEMA.

TPO (75980-60-8) is different. It is prohibited in EU cosmetic products regardless of concentration. Whether a formula contains 0.1% or 5%, the result is the same: the product cannot be legally placed on the EU market.

TMO (270586-78-2) is one of the most common TPO replacements. While there is no formal legal maximum concentration, scientific assessments have supported use levels around 5% in nail products.

MMA (80-62-6) occupies a unique position. Although not specifically restricted under EU cosmetic legislation, it is widely prohibited or restricted within the professional nail industry in the United States and has largely been replaced by EMA-based systems.

A legal concentration is not necessarily a recommended concentration. In real-world salon environments, the greatest risk associated with methacrylate chemistry is not the percentage on the label, but repeated skin exposure to uncured product. Proper application, avoiding skin contact, and complete curing remain the most important safeguards against sensitisation.

07How to work with the rules

If you are a brand or distributor

Decide your market first. EU-bound product must clear Annex II/III; build to the stricter EU standard and the US takes care of itself.
Verify every claim against a CAS number. "HEMA-free" must mean no 868-77-9; "TPO-free" must mean no 75980-60-8. Cross-check the Safety Data Sheet composition, not the marketing copy.
Don't let "HEMA-free" imply "allergen-free." If a formula replaces HEMA with HPMA, say so honestly; the sensitiser risk is similar.
Confirm photoinitiators are TPO-free for the EU. Check that the TPO substitute (e.g. TMO 270586-78-2, BAPO 162881-26-7, TPO-L 84434-11-7) is the one actually used, at what level, and how each supplier classifies it.
Keep a current, CAS-level SDS for every product - ideally one consistent format and responsible party across the range.

If you are a nail professional

Apply gel to the nail plate only; avoid the surrounding skin - this is the single most effective way to prevent methacrylate allergy.
Cure fully and follow lamp specifications; under-cured product means more uncured monomer in contact with skin.
Use gloves and ventilation, and keep SDS sheets accessible as your board requires.
In the EU, respect "professional use only" labelling - it exists for a reason.

08What this means for a professional nail tech

A Nailspiracy nail technician in black nitrile gloves and mask carefully applying gel to a client's nail, with a Nailspiracy gel bottle on the table

Regulations, CAS numbers and classifications are a lot to take in - so here is the part that actually matters at the desk. The real, everyday risk in gel work is not the lamp and not the finished nail. It is skin contact with uncured product. Allergic contact dermatitis from methacrylates such as HEMA and HPMA is the single most common problem in this category, and it builds up from repeated contact between uncured gel and skin - the client's, and yours.

What that means in practice:

Keep product off the skin. Apply to the nail plate, cap the free edge, and wipe any flooding of the sidewalls or cuticle. Most reactions trace back to uncured gel sitting on skin, not to the product itself.
Cure fully, every time. Use the correct lamp and timing for the system you're working with. Under-curing leaves reactive monomer behind - that is what sensitises skin.
Protect yourself; your exposure is cumulative. You handle these products all day. Wear nitrile gloves (not latex), keep airflow or extraction at the desk, and don't breathe filing dust.
The finished nail is inert. Once it's properly cured and on the plate, the enhancement is stable. The moment to respect is the wet product and the application - not the worn set.
Don't lose sleep over trace photoinitiator. In a properly cured product from a transparent supplier, a small amount of photoinitiator like TMO is not where your risk lives. Skin contact with uncured methacrylates is.
Buy on transparency. Choose products with a CAS-level SDS so you know what you're working with. Treat "HEMA-free" as a genuine plus, but still check whether HPMA replaced it, and confirm the photoinitiator.

In short: worry about skin contact and full cure, not about the lamp or a worn manicure. Good technique and honest products handle the rest - which is exactly why Nailspiracy publishes CAS-level Safety Data Sheets, so a tech can make an informed call instead of trusting a slogan.

09Where Nailspiracy stands

Nailspiracy formulates its gel range without HEMA (868-77-9) and without TPO (75980-60-8), the two ingredients now most heavily regulated in the EU. Every product is backed by a Safety Data Sheet that discloses composition at CAS-number level, so professionals and distributors can verify a claim rather than trust a slogan.

Nailspiracy's position is that a "free-from" claim is only worth making if it is precise, verifiable, and honest about trade-offs - including being transparent where a formula uses a HEMA alternative such as HPMA, or which photoinitiator replaced TPO. That standard of disclosure is the brand's baseline, not a marketing flourish.

For product-specific Safety Data Sheets and the full ingredient breakdown of any Nailspiracy gel, see the product page or contact the Nailspiracy team directly.

10Questions & answers

Is HEMA prohibited in the EU?

No. HEMA (CAS 868-77-9) is restricted, not prohibited, in the EU. Since 3 June 2021 it may only be used in professional nail products, which must carry the warnings "For professional use only" and "Can cause an allergic reaction" under Regulation (EU) 2020/1682.

Is HEMA prohibited in the United States?

No. HEMA is permitted in nail products in the US. There is no federal-level prohibition and no mandatory professional-use label, unlike in the EU.

Why was TPO prohibited in the EU?

TPO (CAS 75980-60-8) was classified as a reproductive toxicant (CMR category 1B). Under the EU Cosmetics Regulation, CMR 1B substances are prohibited in cosmetics, so TPO was added to Annex II and prohibited from 1 September 2025.

Is TPO still legal in the US?

At the federal level, yes. As of June 2026 there is no US federal-level prohibition on TPO. This is a key EU-US divergence: a TPO-containing gel can be sold in the US but not in the EU.

How much TPO substitute (TMO) is safe in a gel?

SCCS safety assessments support use levels around 5% in nail products for TMO-type acylphosphine-oxide photoinitiators (CAS 270586-78-2), but this is an SCCS reference level, not a formal legal concentration cap. TMO is not the prohibited TPO (75980-60-8) and has no harmonised EU classification, so suppliers may self-classify it differently. Always confirm the photoinitiator and its level on the product's SDS.

Does "HEMA-free" mean the product is hypoallergenic?

No. "HEMA-free" only means the product does not contain HEMA (868-77-9). Many HEMA-free gels use HPMA (27813-02-1), a related methacrylate that carries a similar skin-sensitisation risk. A HEMA-free product is not automatically allergen-free.

Is HPMA regulated?

HPMA (CAS 27813-02-1) is not specifically restricted in the EU or the US. It is, however, classified as a skin sensitiser (H317) and should be handled with the same skin-contact caution as HEMA.

What is the maximum allowed percentage of HEMA?

The EU restriction sets no numeric maximum; it limits HEMA to professional products with mandatory warnings. Industry formulations commonly go up to about 35%, but that is a practical norm, not a legal cap. The US sets no federal limit either.

What is the difference between MMA and HEMA?

They are different substances. MMA (methyl methacrylate, CAS 80-62-6) is the old acrylic monomer the FDA treats as poisonous and deleterious and that many US state boards prohibit or restrict. HEMA (868-77-9) is a different ester used in gels - permitted in the US and restricted, not prohibited, in the EU. They are routinely confused but are not the same chemical.

What should a nail tech actually worry about?

Skin contact with uncured gel. Allergic contact dermatitis from methacrylates such as HEMA and HPMA is the most common real-world problem, and it comes from uncured product touching skin - not from the lamp or the finished nail. Keep product off the surrounding skin, cure fully, and protect yourself with gloves and ventilation.

Are Nailspiracy gels HEMA-free and TPO-free?

Yes. Nailspiracy formulates its gel range without HEMA (868-77-9) and without TPO (75980-60-8), and publishes CAS-level Safety Data Sheets so the claims can be verified directly.

11Glossary & sources

Annex II: List of substances prohibited in EU cosmetics (Regulation 1223/2009).
Annex III: List of substances restricted in EU cosmetics - allowed only under stated conditions.
CLP: EU Classification, Labelling and Packaging Regulation (1272/2008), which assigns hazard classes.
CMR 1B: Carcinogenic, Mutagenic or Reprotoxic, category 1B - a hazard class that triggers a cosmetics prohibition (this is what happened to TPO).
SCCS: Scientific Committee on Consumer Safety - the EU's independent scientific advisory panel.
Sensitiser: A substance that can cause an allergic reaction with repeated or improper skin contact.
Photoinitiator: The ingredient that starts curing when gel is exposed to UV/LED light (e.g. TPO, TMO, BAPO).
Self-classification: When a supplier assigns a hazard class itself because the substance has no EU-harmonised classification - which is why the same ingredient can be labelled differently by two factories.

Primary sources

Regulation (EC) No 1223/2009 - EU Cosmetics Regulation (Annexes II & III), via EUR-Lex.
Commission Regulation (EU) 2020/1682 - HEMA & Di-HEMA TMHDC restriction, via EUR-Lex.
Commission Regulation (EU) 2025/877 (Omnibus VII) - TPO prohibition effective 1 September 2025.
European Commission - TPO in nail products: Questions & Answers.
ECHA - TPO substance information & CLP Regulation (EC) No 1272/2008.
SCCS (Scientific Committee on Consumer Safety) - opinions underpinning the HEMA and photoinitiator assessments.
US FDA - Nail Care Products (Federal Food, Drug, and Cosmetic Act; MoCRA 2022).
California DTSC - Nail Products Containing MMA; US state cosmetology boards.

This article is educational reference content published by Nailspiracy and reflects the regulatory position as understood in June 2026. Regulations change; substance classifications are periodically updated. It is not legal or regulatory advice. For a specific product, formulation, or market-entry decision, consult the current official regulation and a qualified cosmetic safety assessor or regulatory advisor.