Cal Baier-Anderson, Ph.D., is a Health Scientist.
Andrew Maynard, of the Project on Emerging Nanotechnologies, recently blogged about an Australian study that documented an odd effect of sunscreens containing nanoscale titanium dioxide (TiO2). The study was prompted by the observation that installers of metal roofs who used these sunscreens inadvertently transferred the product onto the roofs. In places where the workers’ skin had touched the painted metal surfaces, the paint showed accelerated weathering. Why? Because the particular type of nanoscale TiO2 in the sunscreen (the anatase crystal form) is photoactive – when it absorbs UV light, it releases free radicals that speed up the oxidation of the underlying paint.