Manicures are a special treat for some and a weekly grooming routine for others. But you may be wondering what is in that colorful, shiny liquid found in pharmacies and nail salons and whether it's safe. Some of the ingredients in nail polish, with names that are often difficult to pronounce, are potentially harmful if ingested, exposed to heat or allowed to come in direct contact with the eye. When used appropriately, however, nail polishes are a safe and simple beauty aid.

Toluene Effects

Toluene, one of the chemicals in nail polish, is a clear liquid that turns into a sweet- or sharp-smelling vapor when exposed to air. Toluene is a solvent, a substance that is used to mix the other ingredients in nail polish. Safe concentrations -- less than 50 percent -- have been established by the Food and Drug Administration 23. Most nail salon customers are not exposed to excessive amounts of toluene. Nail salon workers may have a more significant exposure to the vapors, however. Adverse health effects include:

• dry or cracked skin
  
• headache
  
• numbness
  
• eye or throat irritation and
  
• rarely
  
• kidney or liver damage

Phthalates Effects

Phthalates are a group of oily liquids that help keep polished nails from becoming brittle and cracking. High levels of phthalates, like dibutyl phthalate, have been shown to interfere with reproductive hormones and cause:

• irritation of the eyes
  
• skin
  
• nose
  
• mouth
  
• throat

Because the concentration of dibutyl phthalate in nail polish is very low, however, the risk to humans is considered minimal to negligible. The use of phthalates in the beauty industry is becoming less frequent and has been banned by the European Union.

Formaldehyde Effects

Formaldehyde is used as a nail polish hardener and also as a preservative to prevent bacterial contamination. The FDA has concluded that formaldehyde is not harmful if concentrations are maintained within a safe range -- less than about 0.2 percent by weight. Nail polish containing formaldehyde should be avoided, however, if you have previously experienced an allergic reaction or skin irritation after using nail products that may have contained formaldehyde.

Other Effects

Camphor is a substance that gives nail polish its strength and gloss. In large quantities, it can cause nausea, dizziness and headaches when inhaled, making it a concern for nail salon workers. But exposure to salon patrons is minimal. Butylated hydroxyanisole, a potential toxin, is present in gel manicure products but is considered safe because it is present in small concentrations. Nevertheless, gel manicures may cause brittle nails and dry skin, and this may be secondary to the acetone soaks required to remove the gel. Acetone can also sometimes cause a local allergic reaction, or dermatitis, around the nail. The ultraviolet light required to harden the gel may be harmful, especially if you are having these manicures on a regular basis. Frequent exposure may cause ultraviolet skin damage or even increase your risk of skin cancer in the surrounding area.