New Sunscreen Danger

Carl Lowe 

Your skin makes vitamin D from sunlight. If you always wear sunscreen, you may never get this benefit. And now scientists have identified a new danger from sunscreens.

Researchers report that nanoparticles of zinc oxide, a material widely used in sunscreens, are toxic. These particles, smaller than 100 nanometers, are more toxic than equivalent amounts of soluble zinc; and direct particle-to-cell contact (in the colon) is required to cause cell death. If somebody accidentally eats sunscreen, it could cause serious problems.

The scientists note that there is ongoing concern about the potential toxicity of nanoparticles of various materials, which may have different physical and chemical properties than larger particles. Barely 1/50,000 the width of a human hair, nanoparticles are used in foods, cosmetics and other consumer products. Some sunscreens contain nanoparticles of zinc oxide.

"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 warn.