As many of us nail polish's junkie's know polish can have very harmful chemicals in it, but in recent years many companies have made a push to change their formulas to get rid of many of the toxic chemicals. When a polish brand says they are "3-Free" it means that they have removed Dibutyl Phthalate (DBP), Formaldehyde, and Toluene.
You are probably wondering why are these chemicals so harmful?
-Dibutyl Phthalate (DBP) is used in many nail polishes to prevent chips and cracks. It can cause birth defects if exposed to during or shortly after birth, and it can also cause a low or declining sperm court (http://www.ewg.org/node/8173). DBP has been banned in the European Union in cosmetics since 1976, but no ban has been place on it in the USA.
-Formaldehyde is used in many nail hardeners and nail treatments to help make your nails stronger. When exposed to it, it can cause watery eyes, coughing, and skin irritation. It has also been known to cause cancer after years of prolonged exposure (http://www.nontoxic.com/nontoxic/formaldehyde.html).
-Toluene makes the nail polish easy to apply. It is used as a solvent is things like gasoline, shoe polish, and paint thinners. It's short term effects can lead to irritation of the skin. Over the long term it can lead to nervous system damage.(http://www.ccohs.ca/oshanswers/chemicals/chem_profiles/toluene/health_tol.html)
Many brands have been making the switch to 3-Free formulas for polish. The new formulas are just as good as the old ones, some of them are even better. Some brand of 3-Free polish to check out are Zoya (which is also vegan friendly), OPI, Butter London, Sally Hanson, Revlon, China Glaze, Color Club, and many more.
You can check out a complete list here. They also have other lists for other types of chemical free nail polish.