In this era of ingredient transparency and plant-based everything, entertaining the idea of chemicals as something you might want in your skin-care routine is like announcing to everyone in the natural beauty section of Sephora that you've been stockpiling mustard gas for the past five years. "Chemical" is a dirty word, a vague, catch-all term for a substance that is bad for you. It's why we switch to aluminum-free deodorants , avoid parabens and phthalates, and flock to brands with well-established "clean" reputations. Right? Right.