Ingredient in sunblock damages outer layer of skin
Titanium dioxide (TiO2) is an inorganic compound used in a range of body care products such as sunscreens, makeup, paints, toothpaste and even sweets.
Francesco Turci, PhD, University of Torino and colleagues in new research explain titanium dioxide is generally considered a safe ingredient in commercially available skin products because it doesn't penetrate healthy skin.
Titanium dioxide is a naturally made mineral found in two forms, rutile and anatase. It is a major component of sunblock to prevent the absorption of UV rays from the sun therefore generally making it safe for use however, research has shown that titanium dioxide can cause potentially toxic effects when exposed to ultraviolet light, which is in the sun's rays and is the same kind of light that the compound is supposed to offer protection against. To design a safer TiO2 for human use, the researchers set out to test different forms of the compound, each with its own architecture.
Researchers tested titanium dioxide powders on pig skin, which often substitutes for human skin in these kinds of tests especially since pigs genetic makeup is close to humans. The skin was tested with indoor lighting that contains minimal UV light in it.
The researcher found that rutile, the most common natural form of TiO2, wash off easily and has little effect on the skin. Anatase, a tetragonal mineral and the most other commonly used form was found to be difficult to wash off and damaged the outermost layer of skin even when in low UV light. It appears to do so via "free radicals," which are associated with skin aging. "
The researchers in their conclusion write “Both the higher oxidative potential and the stronger adhesion to skin of anatase and anatase/rutile TiO2 may explain the stronger disorganization induced by these two samples and suggest the use of rutile to produce safer TiO2-based cosmetic and pharmaceutical products.”
In March of this year Friends of the Earth U.S. and Australia had revealed testing results from the Australian Government’s National Measurement Institute, had found numerous sunscreen and cosmetic products that contain anatase titanium dioxide that is potentially hazardous.
The report notes that recent studies have shown that anatase can increase the formation of free radicals when exposed to sunlight and water and there have been numerous researchers that have questioned the safety of its use in sunscreen and skincare products. Anatase is an aggressive free radical producer compared to rutile.
Friends of the Earth had called for an immediate ban on using anatase titanium dioxide in sunscreen and skin products. They also called for safety testing and labeling of Nano-ingredients in sunscreen and other body products.
A survey of nearly 1300 people commissioned by Friends of the Earth and carried out by The Australia Institute found very strong support for both mandatory labeling of nano-ingredients and safety testing of these ingredients before their use in commercial products. The survey found that 85% of Australians want companies to be required to label sunscreens and cosmetics which contain nano-ingredients and 92% of Australians believe sunscreen and cosmetics manufacturers should have to conduct safety tests on Nano-ingredients before using them in products.
The new report by Francesco Turci and colleagues appears in the ACS journal Chemical Research in Toxicology.
More information on sunscreen can be found at the Environmental Working Group website.