Zinc oxide and titanium dioxide are minerals that are ground into fine particles. They’re commonly used in sunscreen products as physical blockers where they sit on the surface of the skin and reflect ultraviolet (UV) rays away from the sun, kind of like how a mirror or shield would work. Both have been used in many different industries for centuries. 

Zinc oxide is a white powdery mineral. Aside from sunscreen, zinc oxide is also a common additive in cosmetics, food, rubbers, plastics, glass, lubricants, paints, adhesives, and many others. The use of zinc compounds dates way back to when early humans used them as paint and medical ointments. The use of zinc oxide as a salve for the eyes and open wounds was mentioned in Indian medical text that is thought to date back to 500 BC. Zinc oxide ointment was also mentioned by Greek physicians in the 1st century AD. As a powder, zinc oxide is commonly found in foot powders and makeup. As an ointment it is used in diaper rash products and sunscreen. The FDA has conducted extensive reviews of the safety of zinc oxide for use in drugs and cosmetics and has stated that it can be safely used. 

Titanium dioxide is also a fine white powder. Aside from sunscreen it has been used for over a hundred years in a range of products including paints, paper, plastics, fabrics, cosmetics, toothpaste, soap, drugs, and more. The FDA has also assessed the safety of titanium dioxide as a colour additive in food, cosmetics, and drugs as well as sunscreen and has deemed it safe. 

Zinc oxide and titanium dioxide are the most common mineral sunscreen ingredients, but are also found in many other products and things we use in our day to day life.