So, ideally, you should bring all your polishes to a household hazardous waste (HHW) facility. While you’re there you can also unload everything from hair dye to paint cans and pesticides. To find a collection site near you, visit earth911.com, click on Recycling Search, and input “nail polish” and your zip code.
If there isn’t an HHW facility in your area, let the polishes dry out by loosening the caps and leaving them outside, away from flames, for 48 hours, then throw them away. This process allows the solvents in the polish to break down and evaporate, which means they won’t seep into the groundwater surrounding a landfill, says Doug Schoon, the president of Schoon Scientific, a company that provides regulatory and technical consultation to the beauty industry.
See more easy ways to go green.