FOEA and others have long been concerned that the chance of greater sun damage to skin is not the only potential health risk posed by nano-sunscreens. Now a new test tube study has found that nanoparticles of zinc oxide, a common sunscreen ingredient, are significantly more toxic to human colon cells than bulk particles of the zinc oxide, when nanoparticles are in direct contact with the cells. The authors suggest that nano-sunscreens could pose health harm if accidentally eaten, for example by children. The nanoparticle concentration tested in their study is equivalent to eating 2 grams of 10% zinc oxide sunscreen.
