Is "10-Free" Nail Polish Actually Safer? What the Numbers Mean — and What Was Really in the Bottles

By S. C. Aris — about the author

Last updated: 2 August 2026

Where the numbers came from

The whole system started with three chemicals. In the 2000s, as the researchers behind the definitive analysis put it, “nail polish manufacturers started promoting ‘3-Free’ products, phasing out three widely publicized toxic chemicals: toluene, formaldehyde, and dibutyl phthalate” (Young et al., Environmental Science & Technology). Those three became known in the industry as the toxic trio, and for a while “3-Free” meant one specific, checkable thing.

Then it became a competition. If three exclusions signalled care, five signalled more care, and seven more still. Today you will find 5-Free, 7-Free, 9-Free, 10-Free, 12-Free, 13-Free, 16-Free and 21-Free on shelves, and the number on the bottle is chosen by the brand’s marketing department. Nobody certifies it. No regulator defines it. There is no auditing body that checks whether a 13-Free polish excludes thirteen things, or which thirteen.

The Young paper — run out of the Harvard T. H. Chan School of Public Health with Boston University and the New York State Department of Health’s Wadsworth Center — did the obvious thing nobody had done: it catalogued what the labels claimed, then took the polishes to a lab and measured what was in them. Its conclusion is the sentence that should sit at the top of every article on this subject: the labels appeared “without any standardization on which n chemicals are excluded.”

What the numbers usually contain — and why “usually” is the point

Below is the pattern most commonly seen on shelf. Treat it as a rough map, not a definition: the study found six competing definitions of 10-Free, and three each of 5-Free and 7-Free. Two bottles with identical numbers can exclude materially different things.

This is the first practical takeaway: the number is not the information — the list is. A 7-Free polish that names TPHP is a more meaningful product than a 10-Free polish that quietly counts “gluten” and “animal by-products” towards its total.

What was actually in the bottles

Here is the part no brand blog will show you. The researchers measured 12 phthalate and 10 organophosphate plasticizers in 40 polishes chosen for popularity and label variety. These are the detection rates and concentrations they published.

Two observations matter more than the individual rows.

First, look at the difference between the medians and the maxima. Most of these compounds turn up nearly everywhere at trace levels — a fraction of a microgram per gram, which is what you would expect from background contamination in any complex manufactured product. The interesting cases are the outliers: TPHP at nearly 8,000 µg/g and DEHP at 331 µg/g are not contamination. Those are ingredients.

Second, and this is the finding that should change how you read a label: the team “measured plasticizers above 100 µg/g in five brands that did not disclose them and in two that excluded them in labels.” Two polishes carried a specific promise on the front of the bottle that the laboratory contradicted.

The substitution problem: what happened when brands dropped one chemical

This is the genuinely new idea in the study, and it is the reason the honest answer to “is 10-Free safer?” is partly, and not in the way you think.

The researchers split their samples into an old generation (unlabelled or 3-Free, n = 12) and a new generation (5-Free through 13-Free, n = 28), and compared them.

The paper’s own framing is that this “identifies TPHP and DEHP as ingredient substitutes for DnBP” — a chain of replacements running from the original 3-Free phthalate, to the organophosphate that replaced it, to the phthalate that in turn replaced that. Each step was a genuine response to consumer pressure. None of them was a return to a plasticizer-free product, because nail polish needs a plasticizer to stop the film cracking as the nail flexes. The FDA describes exactly this function: phthalates are used in nail polishes “primarily at concentrations of less than 10% as plasticizers, to reduce cracking by making the nails less brittle.”

Chemistry does not create vacuums. If you remove the flexible ingredient, you put another flexible ingredient in.

For context: how much has actually come out of the bottle

It is worth keeping the trajectory in view, because the direction of travel is genuinely good. The same paper compiles the highest concentrations found in earlier US surveys alongside its own:

Figures for the three earlier surveys are secondary citations, as compiled in Young et al.’s comparison table. Read them as maxima rather than averages, and read them with care: the sampling designs differ, and Mendelsohn’s polishes were deliberately selected for TPHP content, which inflates that row by design. Even allowing for that, the top of the range has come down substantially — a real public-health win driven largely by label pressure, which is why the right response to a flawed labelling system is to read it better rather than dismiss it.

Why no regulator defines “10-Free”

The reason the numbers are unstandardised is structural, and understanding it makes every label easier to read.

In the United States, the FDA states plainly that “cosmetic products and ingredients, including nail products, do not need FDA approval before they go on the market, with the exception of most color additives.” The legal duty is that a product “must be safe for consumers when used according to directions on the label,” and the agency acts after the fact against products that are not. Crucially, the FDA also notes that “many nail products contain potentially harmful ingredients, but are allowed on the market because they are safe when used as directed. For example, some nail ingredients are harmful when swallowed, but not when used on the nails, because the nail is a barrier, which prevents absorption” (FDA, Nail Care Products).

That is a post-market system with no pre-approved ingredient list, so there is no official register for a marketing claim to point at. Into that vacuum, the industry invented its own numbering.

The European system works the other way round, and the recent gel-polish upheaval shows what an actual regulatory exclusion looks like. When trimethylbenzoyl diphenylphosphine oxide (TPO) received a harmonised classification as a category 1B reproductive toxicant, Article 15(2) of the EU Cosmetics Regulation triggered an automatic prohibition — the European Commission states it had “no discretion to permit continued use” and that there is no sell-through period for CMR 1A or 1B substances (European Commission, TPO in Nail Products Q&A). That is a legal exclusion with a date, a citation and an enforcement mechanism. “10-Free” is a sentence on a box.

Note also how differently the two things behave. A regulatory ban applies to every product in the market at once. A free-from label applies only to the brand that printed it, only to the chemicals it chose, and only for as long as the brand keeps its formula. If your question is specifically about gel polish and TPO, that has its own answer in how do I know if my gel polish has TPO in it — this page is about the numbered free-from labels on conventional polish.

How to actually check a nail polish — the six-step version

This replaces reading the number. It takes about two minutes and it works regardless of what tier the bottle claims.

1. Find the ingredient list, not the marketing panel. Cosmetics sold at retail in the US must carry an ingredient declaration in descending order of predominance. Products sold only into salons, and free samples, are exempt — though the FDA notes that a product labelled “For professional use only” must still carry a list if it is also sold at retail.
2. Look for the plasticizer, because there is always one. Scan for triphenyl phosphate, dibutyl phthalate, DEHP or bis(2-ethylhexyl) phthalate, resorcinol bis(diphenyl phosphate), or a generic “plasticizer.” If none is named and the polish is not a water-based formula, ask what performs that job.
3. Count the actual exclusions the brand lists, and ignore the headline number. If the brand will not publish its own n-Free list chemical by chemical, the number means nothing. Reputable brands publish theirs.
4. Discount the non-chemical entries. Gluten, soy, animal by-products and “cruelty” are legitimate reasons to choose a brand. They are not toxicological exclusions, and they should not be counted towards a safety claim.
5. Check for formaldehyde by all of its names. The FDA warns it “may be listed on the product label as formaldehyde or by different names, such as ‘formalin’ and ‘methylene glycol’” — and separately as toluene sulfonamide/formaldehyde resin, which is a different ingredient with its own allergy risk.
6. Weight your effort by your exposure. A polish worn twice a year is a different question from a fortnightly gel cycle, and both are a different question again from working eight-hour shifts in a salon. The label matters most to the people with the most contact.

The thing no free-from label can fix

Here is what tends to get lost in the chemical argument. Almost nobody’s nails are visibly damaged by parts-per-million of a plasticizer. They are damaged by the process: the buffing before application, the rigid film sitting on the plate for three weeks, the acetone soak that strips lipids out of keratin, and the peeling-off that takes layers of nail plate with it. Not one of those things appears on any n-Free list, because none of them is an ingredient.

The American Academy of Dermatology is direct about the mechanical side. Gel manicures “can be tough on nails” and “can cause nail brittleness, peeling and cracking,” and repeated use “can increase the risk for skin cancer and premature skin aging on the hands” — which is why the AAD recommends broad-spectrum SPF 30+ on the hands before curing, or opaque gloves with the fingertips snipped off (AAD, Gel manicures). It also recommends taking a polish holiday of one to two weeks or longer to let nails repair, and applying a moisturising product to nails and cuticles several times daily in between.

There is also a lesson about strengtheners that sits awkwardly with the whole free-from framing. The AAD notes that “polishes that contain strengthening ingredients increase nail stiffness, which may make nails break more frequently” (AAD, Manicure and pedicure safety). The FDA says the same thing about the classic hardener chemistry: formaldehyde “bonds with the keratin that occurs naturally in the nails, making the nails harder,” but “using these nail hardeners often, however, may make nails brittle and more likely to break or peel.”

Harder is not stronger. A nail that cannot flex is a nail that snaps at the stress point instead of bending past it. We unpacked that in does nail hardener actually weaken your nails, and it is the reason the aftercare question is a different question from the ingredient-label question.

The AAD’s other everyday points are worth repeating because they cost nothing: moisturise after removing polish, since most removers contain chemicals that dry the nails; never cut or forcefully push back cuticles; and if you have persistent nail problems, artificial nails are not the fix.

Frequently asked questions

Is 10-Free nail polish actually safer?

Sometimes, but the label alone cannot tell you. There is no legal or certified definition of 10-Free, and an analysis of 40 polishes from 12 brands found six different definitions of the term in use. The measured data was genuinely encouraging in one respect: polishes carrying 5-Free through 13-Free labels had dramatically less triphenyl phosphate than unlabelled or 3-Free polishes. But the samples without triphenyl phosphate contained roughly 45 times more DEHP, a phthalate that appears on almost no free-from list. Read the brand’s published exclusion list rather than the number.

What does 10-Free mean exactly?

It means the brand has excluded ten ingredients of its own choosing. Most lists build on the original toxic trio of toluene, formaldehyde and dibutyl phthalate, then add formaldehyde resin, camphor, xylene, ethyl tosylamide, parabens, synthetic fragrance, animal-derived ingredients and sometimes triphenyl phosphate. Because there is no standard, two 10-Free polishes can exclude materially different sets of chemicals, and the one that names triphenyl phosphate is the more meaningful product.

Is a 13-Free or 21-Free polish better than a 10-Free one?

Not necessarily. The number counts exclusions, not risk reduction, and longer lists often reach their totals by adding items such as gluten, soy or animal by-products, which are dietary or ethical rather than toxicological exclusions. A shorter list that names the plasticizer is more informative than a longer list padded with ingredients that were never in nail polish to begin with.

Can a nail polish be free of all plasticizers?

Realistically, no — a conventional polish film has to flex with the nail without cracking, and something has to make it do that. The FDA describes phthalates as being used in nail polishes at concentrations of less than 10% precisely to reduce cracking. This is why removing one plasticizer has historically meant introducing another, a pattern the Harvard-led analysis traced from dibutyl phthalate to triphenyl phosphate to DEHP. Products with no film to keep flexible, such as a lipid nail concentrate, sidestep the question entirely.

Do free-from labels apply to gel polish too?

Gel is a different chemistry, cured under a lamp rather than dried by solvent evaporation, so the relevant ingredients are photoinitiators and acrylate monomers rather than plasticizers. Free-from numbering is far less common on gel, and the meaningful exclusions there are regulatory. The EU prohibited the photoinitiator TPO in cosmetics from 1 September 2025 following its classification as a category 1B reproductive toxicant, with no sell-through period.

If the labels are unreliable, what should I actually do?

Read the ingredient declaration rather than the marketing panel, look specifically for the plasticizer, ask the brand for its chemical-by-chemical exclusion list, and scale your effort to your exposure — occasional polish is a very different situation from a fortnightly gel cycle or salon work. Then put the remaining effort where the visible damage actually comes from: gentle removal, no peeling, a polish holiday, and daily lipid conditioning of the plate and cuticle.

Does any of this mean I should stop wearing nail polish?

Nothing in the published record supports alarm about occasional consumer use, and the highest plasticizer concentrations reported in US nail-polish surveys have come down substantially over the past decade. The groups with the strongest case for choosing carefully are people who are pregnant or trying to conceive, and nail technicians with daily occupational exposure rather than intermittent consumer exposure.

Related reading

• How do I know if my gel polish has TPO in it? The label-reading guide
• Does nail hardener actually weaken your nails? The formaldehyde paradox
• Do nails really need to breathe? The truth about polish breaks
• How to repair damaged nails after gel or acrylic removal
• Why are my nails so weak and brittle — and what actually helps?
• Should you buff the ridges out of your nails?

Sources

1. Young AS, Allen JG, Kim U-J, Seller S, Webster TF, Kannan K, Ceballos DM. “Phthalate and Organophosphate Plasticizers in Nail Polish: Evaluation of Labels and Ingredients.” Environmental Science & Technology — doi:10.1021/acs.est.8b04495 (origin of 3-Free; no standardisation of n-Free labels; six definitions of 10-Free; 40 polishes from 12 brands; detection rates and concentrations; old- vs new-generation TPHP; DEHP in TPHP-free samples; undisclosed and label-contradicting plasticizers; comparison table of earlier US surveys).
2. US Food and Drug Administration — Nail Care Products (no pre-market approval except most colour additives; safety-when-used-as-directed standard; the nail as a barrier; retail ingredient declaration and the “professional use only” exemption; formaldehyde and its alternative names; toluene sulfonamide/formaldehyde resin allergy; hardeners causing brittleness; phthalates as plasticizers under 10%; the 2010 DBP survey; toluene being phased out).
3. Cosmetic Ingredient Review Expert Panel, toluene safety assessments 1987 and 2005 — as reported by the FDA in the source above.
4. European Commission, DG Internal Market, Industry, Entrepreneurship and SMEs — TPO in Nail Products – Questions & Answers, 7 August 2025 (Article 15(2) automatic CMR prohibition; Regulation (EU) 2025/877; no discretion; no sell-through period).
5. American Academy of Dermatology — Gel manicures: Tips for healthy nails (brittleness, peeling and cracking; skin cancer and photoaging risk from repeated UV exposure; SPF 30+ or opaque gloves; polish holiday of one to two weeks; daily moisturising between polishes).
6. American Academy of Dermatology — Manicure and pedicure safety (strengthening polishes increase stiffness and may make nails break more frequently; moisturise after removing polish; do not cut or force back cuticles; artificial nails not recommended for brittle nails).
7. Mendelsohn E et al., 2016 — highest reported TPHP concentration; secondary citation, as compiled in Young et al.’s comparison of earlier US nail-polish surveys.
8. CalEPA 2012 and Guo & Kannan 2013 — highest reported TPHP and phthalate concentrations; secondary citations, as compiled in Young et al.’s comparison table.

This article is general consumer information about cosmetic ingredients and product labelling. It is not medical advice. Provité Nail Elixir is a cosmetic product intended to support the appearance of the nails; it is not intended to diagnose, treat or prevent any condition. If you have a nail or skin problem that concerns you, or you are pregnant and unsure about a product, speak to a doctor or dermatologist.