A scientific committee of the European Union just issued a report concluding that current approaches to assess the potential risks of nanomaterials in cosmetics, including sunscreens, are inadequate. After a thorough review of current risk assessment approaches, the committee concluded that "a review of the safety of the insoluble nanomaterials presently used in sunscreens is required" and recommended a case-by-case risk assessment of all nanoparticles used in cosmetics. Importantly, the committee also called for the "urgent development of new methodologies" to assess the potential for nanomaterials to penetrate skin, persist in the body, accumulate in organs and body tissues, and cause health harms. Since most tests thus far have been on healthy intact skin, the report also called specifically for tests that examined the potential for nanoparticles to penetrate injured, sunburnt or diseased skin.

An August 2007 report by Friends of the Earth has more information on nanoparticles and sunscreens.

Many sunscreens contain nanoparticles of zinc or aluminum. At normal scale they are effective sunblockers, and at nanoscale they have the added cosmetic benefit of making the sunscreen more fluid and transparent instead of white. Is it worth the potential risk? I'll take my sunscreen thick and white, please.

Engineered nanoparticles are also in deodorants, toothpastes, shampoos, anti-aging creams, and nail polish....though labeling is not mandatory so the consumer is largely uninformed. In addition to the word 'nano', look for words like 'pulverized' or 'micronized' as a hint that the product may contain nanoparticles.  Call the manufacturer if you are not sure...and, let me know what they say!

For more insight into the EU scientific committee's report, check out this post over at EDF's "Nanotechnology Notes" blog.