SPF has been in our vocabulary for as long as we could ask someone to smear it on our backs. But how about retinyl palmitate (RP)? Among other recommendations that you're probably more familiar with ("wear at least SPF 30! Reapply after taking a dip!") The EWG's 2010 Sunscreen Guide red flagged this vitamin A derivative–which appears in nearly half of sunscreens–because of its link to skin cancer. And according to recent Senate and EWG action (with the research to back it up), this common sunscreen ingredient is more dangerous than we thought–and appears in multiple personal care products beyond sunscreen. Why exactly don't we know more about the risks?

Yes, that was a rhetorical question. The FDA has been reviewing data on RP and cancer for about a year, including one recent study showing that tumors and lesions developed up to 21 percent faster in lab animals coated in a cream containing RP, than those coated in a RP-free cream. Plus, NPICenter reported that the ingredient also appears in hundreds of anti-aging serums (it's well-known for its anti-wrinkle benefits), skin creams, cosmetics, and even food products. And the FDA has taken zilch action to alert consumers of the risk, let alone regulate use of the ingredients.

Why? The ingredient's prominence in the skin care industry could have something to do with it, reports NPIcenter. This includes a risk to products using other members of the retinoid family, including popular anti-acne and skin care ingredients Retinol, Retin-A and Tretinoin. But with help from Senator Charles Schumer (D), who is urging the FDA to release the chemical data, and the EWG's persistent activism, hopefully we'll see some progress soon. In the meantime, continue to consult with the EWG before picking your sunscreen this summer. Also check out our picks for this year's best natural sunscreens.