The U.S. Environmental Protection Agency is studying how an ingredient in sunscreen reacts when exposed to chemicals in swimming pool water.
This is just a small part of a much larger study examining the environmental impacts of engineered nanomaterials, which are used in a wide variety of consumer products. In this case, scientists are zeroing in on titanium dioxide (TiO2) — the thing that protects skin from harmful UV rays.
Here’s the thing about titanium dioxide: In the presence of water and UV radiation, it decomposes into other molecules, including a reactive oxygen species that has been shown to cause tissue damage. To prevent this, sunscreen manufacturers wisely place a protective coating around the material, called aluminum hydroxide.
EPA researchers wanted to learn how the protective layer holds up against the rigors of a chemically treated pool.