We know that a lot of people—us included—want to minimize their exposure to harmful toxins, such as BPA in plastic bottles. But hoping to make your world chemical-free is a fool’s errand. “A chemical is a substance made up of atoms that are connected by bonds to form a molecule. That means that literally everything you see or smell is a chemical or a mixture of chemicals,” according to Gordon Gribble, Ph.D., a chemistry professor at Dartmouth University. That includes things that are “all natural,” so you needn’t worry that all chemicals are inherently bad.