SALT LAKE CITY, June 25 (UPI) -- Nanoparticles of zinc oxide can harm colon cells and may be toxic if accidentally eaten, U.S. researchers warn.
Philip Moos of the University of Utah and colleagues said there is concern about the potential toxicity of nanoparticles of various materials, which may have different physical and chemical properties than larger particles.
The study, published in the Chemical Research in Toxicology, found particle size affects the toxicity of zinc oxide, a material widely used in sunscreens. Particles smaller than 100 nanometers are slightly more toxic to colon cells than conventional zinc oxide, the study said.
"Unintended exposure to nano-sized zinc oxide from children accidentally eating sunscreen products is a typical public concern, motivating the study of the effects of nanomaterials in the colon," the researchers said in a statement.
The researchers found the nanoparticles were twice as toxic to the cells as the larger particles. The concentration of nanoparticles that was toxic to the colon cells was equivalent to eating 2 grams of sunscreen -- about 0.1 ounce, the study said.
