The safety of nanosized particles in titanium dioxide– and zinc oxide–based sunscreens

Given the increasing incidence and prevalence of skin cancer, dermatologists are more frequently recommending sunscreens to their patients. However, the safety of titanium dioxide and zinc oxide nanosized particles in the majority of sunscreens has come under scrutiny from governments and the general public. We sought to characterize the use, safety, and regulatory state of nanosized particles in titanium dioxide and zinc oxide in sunscreens based on studies and position statements from 1980 to 2008. Although we found no evidence of significant penetration of titanium dioxide and zinc oxide nanosized particles beyond the stratum corneum, further studies must be done to simulate real-world conditions particularly in sunburned skin and under ultraviolet exposure.