Cosmetics are a part of billions of people’s daily lives, from makeup and skincare to hair dye and, of course, nail polish. But how much do you really know about what’s being painted onto your fingertips, or what kinds of chemicals nail technicians are exposed to every day? Read on to find out more.
These days, nail polish—also known as nail varnish or enamel—can come in several different forms. The most conventional home nail polish is made from the polymer nitrocellulose dissolved in a volatile organic solvent—usually ethyl or butyl acetate. This is applied to the nail and air-dried to remove the solvent and leave behind a smooth and hard polymer surface.
Nail salons offer more technical services which use additional products and offer more lasting results than store-bought polishes. They are often differentiated as acrylic, gel, and dip powder manicures—however they all use similar ingredients at a chemical level, just in different forms: they’re all peroxide-initiated acrylic polymers.
The reaction which causes nails to harden is caused by a reaction initiator—benzoyl peroxide. This molecule is used in almost all professional manicure services and is one of the most widely used initiators for polymerisation reactions in general.
Acrylic nails combine an acrylic polymer powder (usually polyethylmethyl methacrylate) with a monomer liquid (usually ethyl methacrylate) which then forms a paste and is brushed onto natural nails. The polymerisation process is initiated by benzoyl peroxide, a radical oxidising agent, which is included in the powder, and dries hard in air after about 15 minutes of working time. Acrylics are mouldable and set very strong so they can be used as a protective base for natural nails or can be shaped into sturdy nail extensions. Acrylic powder can be coloured by design or can be white and have polish painted on top.
Gel nail polish is a similar consistency to standard nail polish in that it comes in liquid form in a bottle, however the chemistry behind it differs. Most gel polishes are made from a methacrylate monomer and also use a benzoyl peroxide initiator; however, the gel polish is designed so that air is not enough to cure the polymer. Instead, UV light reacts with the initiator, activating the radical which triggers the polymerisation and curing process.
Nail dipping powders are very similar chemically to acrylics but generally easier to work with because they dry faster and require less technical skill to apply. The powder is made up of acrylic polymers, a benzoyl peroxide initiator, and titanium dioxide—a white powder which is added to increase the strength of dip powder manicures, as well as change the opacity and vividness of the powder colour.
The powder is bonded using cyanoacrylate—an adhesive better known as superglue—and sets very quickly compared to other manicure types. Nails are coated in the binder and then dipped in powder, after which it can be buffed smooth and sealed.
Acetone is one of the most commonly used organic solvents worldwide. It is capable of dissolving paints, plastics, and glues, and is the active ingredient in nail polish remover. It very effectively dissolves and removes nail polish, acrylic, dipping powder, and even plastic artificial nail tips.
Acetone is highly flammable and can irritate the nose, throat, eyes, and lungs if exposed in significant amounts. Although skin contact is inevitable with the use of products such as nail polish remover, irritation and damage to the skin is still a possibility. Acetone-free nail polish remover often uses ethyl acetate as the active solvent, which is considered to be gentler on the skin and natural nail, but is not as powerful at removing dip powder and gel nails. For more information on the hazards of acetone, click here to download a FREE copy of the Chemwatch-authored safety data sheet.
These chemicals were used as additives in nail care products for decades before their harmful exposure effects were recognised as a concern. Now these chemicals are gradually being phased out in ordinary consumer products.
Many conventional and gel nail polishes contain plasticizers—most commonly dibutyl phthalate. However, over the last 20 years, phthalates have been phased out due to concerns over their endocrine disrupting properties, and correlation with increased rates of birth defects. Many jurisdictions have banned phthalates in plastic manufacturing, though legislation for cosmetics is lagging behind, leaving consumers to find the safest option themselves.
Formaldehyde, often used as a preservative and steriliser, is also added to nail hardening agents. Formaldehyde is a known carcinogen, as well as a skin and airway sensitiser if there is a high level of exposure.
Toluene is an organic solvent which is used to keep nail polish smooth, but it has also been linked to effects on the nervous system as well as birth defects. It has been banned in the EU for quantities over 0.1% by weight as of 2005.
Many cosmetics companies have replaced, or are in the process of replacing, these harmful ingredients with safer alternatives. Keep an eye out for labels reading “3-free” or “non-toxic” when buying nail polish and stick to well-known brands rather than discount products which may try to cut corners on quality and safety.
Many chemicals are not safe to be inhaled, consumed, or applied to the body. To avoid accidental consumption, mishandling, and misidentification, chemicals should be accurately labelled, tracked, and stored. For assistance with this, and chemical and hazardous material handling, SDS, labels, Risk Assessment, and heat mapping, you can contact us at firstname.lastname@example.org.