Lipstick eventually disappears from your lips because you unknowingly eat it. You might think lipstick is harmless — after all, it's a cosmetic that goes on your mouth — but science says otherwise. According to a study carried out by researchers at the University of California, Berkeley (via Environmental Health Perspectives), lipsticks and lip glosses contain toxic chemicals, such as cadmium, aluminum, chromium, lead, and various toxic metals (via WebMD).

Katharine Hammond, professor of environmental health sciences at UC Berkeley, told HealthDay News that levels of toxic chemicals contained in lipsticks and lip glosses "approach or exceed acceptable daily doses based on public health guidelines," per WebMD. If a lipstick contains lead and you ingest even small quantities of it every day, it could have serious health repercussions.

According to the aforementioned study, there is no acceptable daily intake of lead because its toxic nature can affect the kidneys, heart, brain, bones, and digestive system. Likewise, metals such as aluminum can also be quite dangerous for the body as it is a neurotoxin, meaning that it can affect a person's brain and the central nervous system (via The People's Pharmacy).

Does this mean you should stop wearing lipstick altogether? Not quite. According to Beauty Bakerie, if you look for lipsticks that are paraben-free and smudge-proof, and which are formulated to stay on the lips for longer durations, then you can continue to wear them. However, it's best to check the ingredients and stay away from lipsticks that contain lead or other toxic ingredients.