I have previously blogged about the environmental risks of nano-particle titanium dioxide. Since I had a role in promoting photocatalytic TiO2, I feel responsibility to report cautionary news:

"Sunscreens have been shown to give the most effective protection for human skin from ultraviolet (UV) radiation. Chemicals from sunscreens (i.e., UV filters) accumulate in the sea and have toxic effects on marine organisms. In this report, we demonstrate that photoexcitation of inorganic UV filters (i.e., TiO₂ and ZnO nanoparticles) under solar radiation produces significant amounts of hydrogen peroxide (H₂O₂), a strong oxidizing agent that generates high levels of stress on marine phytoplankton. Our results indicate that the inorganic oxide nanoparticle content in 1 g of commercial sunscreen produces rates of H₂O₂ in seawater of up to 463 nM/h, directly affecting the growth of phytoplankton. Conservative estimates for a Mediterranean beach reveal that tourism activities during a summer day may release on the order of 4 kg of TiO₂ nanoparticles to the water and produce an increment in the concentration of H₂O₂ of 270 nM/day. Our results, together with the data provided by tourism records in the Mediterranean, point to TiO₂ nanoparticles as the major oxidizing agent entering coastal waters, with direct ecological consequences on the ecosystem."*

For more information about my concerns and what to do about it, see Environmental Building News.

*Abstract and image from

Environ. Sci. Technol., 2014, 48 (16), pp 9037–9042

DOI: 10.1021/es5020696

Publication Date (Web): July 28, 2014