Nail polish has always stunk. It was a fact we all grew up with. But the irritants in polish go far beyond just smelling poorly. Things like toluene, a chemical that's connected to reproductive abnormalities; formaldehyde, a potentially cancer-causing carcinogen; and dibutyl phthalate (DBP), which is banned in Europe because it can cause reproductive challenges, have long been ingredients we've been using to paint our nails. But with the uptick of brands paying closer attention to toxicity levels in products, there are now many safe polishes to choose from. See how they stack up.