Nail polishes (also called lacquers or enamels), base coats, top coats, nail hardeners, and nail treatments are coatings applied to the nail plate to provide a pleasing look and to address specific nail plate conditions, such as soft, peeling or brittle nails. Upon application of the polish, treatment, or hardener, the solvents in the product quickly evaporate, leaving a coating of film behind. Nail treatments are coatings applied to the nail plate for a specific purpose and include 1) base coats to increase polish wear, 2) ridge fillers to make the nail smooth, and 3) top coats designed to increase polish longevity and gloss. Nail hardeners or strengtheners, as their name imply, are designed to harden or strengthen the nail. Polish removers are designed to soften polishes, treatments, or hardeners so that the coating on the nail can be easily removed. Ingredients used in polish removers can include acetone, ethyl acetate, and isopropyl alcohol.
Nail polishes, treatments and hardeners have very similar formulation composition. All contain a film-former, such as nitrocellulose or cellulose acetate butyrate, to make the product hard and shiny when it dries. To make the film tough and resilient, a resin or secondary film-former such as tosylamide/formaldehyde resin or tosylamide/epoxy resin is used. To prevent chips and cracks, one or more plasticizers, including triphenyl phosphate, trimethyl pentanyl diisobutyrate, camphor, and dibutyl phthalate may be included. Low levels of solvents, including ethyl acetate, butyl acetate, isopropyl alcohol, and toluene, are used to help products flow smoothly. Colored polishes or products contain FDA-approved colorants or pigments which are evenly distributed in the product due to the inclusion of a suspension agent or clay, such as stearalkonium hectorite or bentonite. To prevent color fading, a UV stabilizer, such as benzophenone-1, is often added. Nail hardeners may also contain a small amount of formaldehyde to harden or strengthen the nail.
Nail Product Safety
Nail polish products have been used safely for many decades by millions of people. Fingernails and toenails are made of keratin, which is hard and largely impenetrable. Once nail polishes, treatments, and hardeners dry, the ingredients in the products become embedded in the hardened film coating on the surface of the nail, and are not able to be absorbed by the body or released into the air.
For many years, information has been circulating in the media alleging potential adverse health effects from exposure to certain ingredients in nail care products, such as toluene, formaldehyde, and dibutyl phthalate. However, the Food and Drug Administration states on its website that all of these ingredients based on available safety information are safe under current conditions of use in nail products. Furthermore, with the exception of some usage of formaldehyde in nail hardeners, the Personal Care Products Council’s (PCPC) member companies, who sell the majority of U.S. nail products, have reduced or eliminated their use of these ingredients.
The safety of Formaldehyde as used in nail hardeners has been reviewed by the Food and Drug Administration (FDA). FDA notes nail hardeners containing formaldehyde may cause an irritation or allergic reaction to those individuals sensitized to this compound. If you are allergic to formaldehyde, have previously experienced an allergic reaction to nail preparations, or for any other reason wish to avoid this ingredient, you should read the product ingredient statement on the label to determine whether formaldehyde or related ingredients, such as formalin and toluene sulfonamide-formaldehyde resin, are present. In Europe, the Scientific Committee on Consumer Safety (SCCS) reviewed formaldehyde use in nail hardeners in 2014 and concluded that formaldehyde can be safely used up to 2.2% to harden or strengthen nails.
Toluene was reviewed by the Cosmetic Ingredient Review Expert Panel in 1987, when the Panel determined that it was safe for cosmetic use in nail products when limited to concentrations no greater than 50 percent. The Panel re-evaluated the safety of toluene in 2005 and confirmed its original conclusion.
The safety of dibutyl phthalate was first assessed by the Cosmetic Ingredient Review (CIR) Expert Panel in 1985. The CIR Expert Panel evaluated the scientific data and concluded that dibutyl phthalate is safe for use in cosmetics and personal care products. In 2002 and 2005, as part of the scheduled re-evaluation of ingredients, the CIR Expert Panel considered available new data on this ingredient and reaffirmed the previous conclusion.
The Nail Manufacturer Council on Safety (NMC), a subset of the Professional Beauty Association (PBA) also seeks to educate industry professionals and consumers about nail care and safety issues. To learn more, please visit: https://probeauty.org/nmc/.