An August 15, 2016, U.S. Environmental Protection Agency (EPA) blog item describes EPA’s research on sunscreens containing engineered nanomaterials and how they might change when exposed to chemicals in pool water.  According to EPA, many sunscreens contain titanium dioxide engineered nanomaterials, which are often coated with other materials such as aluminum hydroxide to shield skin from reactive oxygen species.  EPA researchers are testing to see whether swimming pool water degrades the aluminum hydroxide coating, and if the extent of the degradation is enough to allow the production of potentially harmful reactive oxygen species.  Results show that after three days, pool water caused the aluminum hydroxide coating to degrade, which can reduce the coating’s protective properties and increase the potential toxicity.  EPA notes that even with degraded coating, the toxicity measured from the coated titanium dioxide was significantly less than the uncoated material, and “these sunscreens still provide life-saving protection against UV radiation.”  According to EPA, the study provides evidence that when released into the environment, nanomaterials undergo physical and/or chemical transformations — “an important consideration when measuring the impact of these materials on public health and the environment.”

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