Last year (July 9, 2009), I wrote about the Environmental Working Group (EWG) and their meta-analysis of the studies conducted on the use of titanium dioxide and zinc oxide nanoparticles in sunscreens. Much to the EWG’s surprise, they gave the sunscreens with nanoparticles a passing grade. The EWG still examines sunscreens and, according to an article by Ariel Schwartz on the Fast Company site, have some concerns,

Sunscreen is supposed to protect us from cancer, but a new report from the Environmental Working Group claims that many products don’t do what they’re supposed to. Some sunscreens contains ingredients that might even trigger skin tumors and lesions, according to the EWG’s 2010 Sunscreen Guide.

This year’s problem (from the EWG site),

A surge in exaggerated SPF claims above 50 and new disclosures about potentially hazardous ingredients, in particular recently developed government data linking the common sunscreen ingredient vitamin A to accelerated development of skin tumors and lesions.

If you plan to spend some time investigating  the EWG’s report on sunscreens, be prepared to receive a request to sign up (but it’s not required) before viewing the report.