Commonly found in: nail polish, synthetic fragrance, and hairspray.
Why you should avoid it: Phthalates can interfere with our bodies' normal hormone functions. Often they're hiding under the innocent-sounding "fragrance/parfum" written on your ingredient list, though. "Look for companies who fully disclose fragrance ingredients," a spokesperson for Beautycounter said. Anything with undisclosed fragrance can mask a combination of hundreds of different ingredients.