Q: What’s the difference between chemical sunscreens and non-chemical sunscreens? You’ve said everything’s a chemical except light and electricity, so how can a sunscreen not contain chemicals?
A: All sunscreens contain chemicals, regardless of whether they’re touted as chemical or chemical-free. For that matter, anything in a bottle contains chemicals, whether it’s a drug, cosmetic, or food. Chemicals are formed when two or more atoms join together. Therefore, all ingredients used in cosmetics or drugs are chemicals, even if they come from nature or the manufacturer claims that their products are chemical-free.
Sunscreens are chemicals that can protect skin by absorbing, reflecting, or scattering ultraviolet (UV) radiation. The most popular sunscreen ingredient—octinoxate—is like other organic (meaning it contains at least one carbon atom, not that the sunscreen was grown organically) sunscreens in that it absorbs UV radiation, employs chemical processes to lower UV radiation energy levels, and then releases the energy as heat. This is why a person might feel warmer than usual when the sunscreen-protected skin is under the sun. Other sunscreens, such as the inorganic mineral-derived titanium dioxide and zinc oxide, mostly work by partially blocking UV radiation, then scattering, or reflecting, energy rays. They also absorb and release light, but not to the degree that organic sunscreens do.
Some companies explain the difference between organic and inorganic sunscreens by focusing on their chemical reactivity with UV radiation. This is how the classifications for “chemical” and “chemical-free” sunscreens came about, which can be misleading if you don’t understand chemistry. In reality, though, all sunscreens are chemicals.