Toxic Sunscreen (IMAGE) American Chemical Society Caption Sunscreens contain nanoparticles of zinc oxide -- used to prevent the damaging effects of sunlight -- that can harm colon cells and may be toxic if accidentally eaten. Credit iStock Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.