The Science of “3 Free” Nail Polish

I love nail polish. I hoard nail polish. On bad days, just gazing at my nails fills me with a sense of happiness and calm. As a scientist who experiences a lot of failure, discombobulation, and flailing, I NEED THAT CALM.

As a scientist, of course, I like to know the why of things. Which is why I was curious about the “3 Free” push made by many of the major nail polish brands, including OPI, China Glaze, Essie, Sally Hansen and many others. Let me tell you about what I found when I went searching for the back story regarding “3 Free,” the chemicals involved and what that means for you, the consumer:

“3 Free” refers to three ingredients that used to be included in most nail polishes: dibutyl phthalate (DBP), toluene and formaldehyde.

Dibutyl Phthalate-

DBP was included in nail polish formulas because it acted as a binder and improved the durability and the ability of nail polish to last a long time without chipping. Which, as anyone who polishes their nails can tell you, is a primary frustration with polish. However, general studies on this chemical (not performed specifically on nail polish) have shown that DBP has an effect of the in utero development of male sexual system in rats (1). There is also an effect during the pubertal sexual development of male rats and mice. In addition, DBP has been shown to antagonize the thyroid receptor (2). This means that DBP binds to the thyroid receptor and blocks the ability of necessary thyroid hormones to bind there.  This blockage of thyroid hormones to normally bind to thyroid receptors can have an effect on normal brain development. Studies have also been carried out on the effect of DBP on metabolism and liver function with negative results.

In humans, a study performed in Korea (3) linked phthalate exposure to intelligence levels in children. There was a limiting factor in this study, but there is a frightening correlation, meaning that increased phthalate exposure and decreased intelligence seem to occur in the same children when maternal IQ was controlled for. This does not mean necessarily that one caused the other, and more than one phthalate was looked at; all this means is that there is some cause for concern and more studies are necessary.


Toluene is a solvent that was used in many nail polish formulations to dissolve other ingredients and make a nice smooth, easy-to-apply polish. After application to the nail, toluene will volatilize, or evaporate and leave a smooth, glossy finish. Toluene is found naturally in crude oil and in the tolu tree.

According to the Centers for Disease Control, the effect of toluene on humans at low, environmental doses is unknown. However, short term, high load doses can result in poor performance on cognitive tests as well as eye and upper respiratory irritation. Chronic solvent abuse (such as huffing) can result in dementia and brain damage.

Nail color: MAC Demi Blanc. Courtesy of OneBigPear.

Formaldehyde resin-

Technically, nail polishes don’t contain straight formaldehyde, they contain a resin called tosylamide formaldehyde resin. This resin ensured that the polish adhered to the nail’s surface and made the polish tough and resilient. Interestingly, it seems that tosylamide formaldehyde resin (TS-F-R), is a major allergen and can cause contact dermatitis. In fact, TS-F-R can actually remain active and bioavailable for up to three days after painting your nails (4). A search through only turns up allergy references in regards to tosylamide formaldehyde resin, indicating that the resin likely doesn’t have the carcinogenic (cancer causing) properties of its cousin, formaldehyde.

Nail color: Zoya Edyta. Courtesy of Hermionedanger.

What have we learned? That DBP seems to be a pretty bad chemical, all the way around. Toluene may not be quite so bad for you, but the jury is out, given that more study is needed to study the effect of low doses. Formaldehyde resin seems mainly to cause allergic reactions, something crucial to know if you are predisposed to skin allergies or have contact dermatitis.

I, for one, am happy that many of my favorite nail polish brands have moved to a “3 Free” formulation. In recent years, more and more studies have emerged about the dangers of additives in everyday products. It is incumbent upon us to be proactive about knowing the science behind what we use every day and how it could harm us. Also, write to your congress people and express your support for NIH funding!

Did I make a mistake? Do you disagree with something I wrote? Have a question? Email me at!


Relevant and interesting references: – CDC information regarding DBP chemical, monitoring and the effect of exposure

1.)McKee et al. NTP center for the evaluation of risks to human reproduction reports on phthalates: addressing the data gaps. Reprod Toxicol. 2004 Jan-Feb;18(1):1-22.

2.) Li N. et al. Dibutyl phthalate contributes to the thyroid receptor antagonistic activity in drinking water processes. Environ Sci Technol. 2010 Sep 1;44(17):6863-8.

3.) Cho SC et al. Relationship between enviromental phthalate exposure and the intelligence of school-age children. Environ Health Perspect.2010 Jul;118(7)1027-32. Epub2010 Mar 1. – CDC information regarding toluene, monitoring and exposure

4.) Hausen BM et al. The allergens of nail polish (I). Allergenic constituents of common nail polish and toluenesolfonamide-formaldehyde resine (TS-F-R). Contact Dermatitis. 1995 Sep; 33(3):157-64.

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