Environmental Working Group’s 2010 Sunscreen Guide that vitamin A, a common ingredient in personal care products, is a potential cancer promoter. I wasted no time checking my usual sunscreen, and there it was in black and white on the ingredients label: retinyl palmitate, a derivative of vitamin A. According to the Washington, D.C.-based EWG’s analysis of nearly 500 products, 41 percent of sunscreens, including some natural brands, contain retinyl palmitate.

The EWG based its damning assessment of vitamin A on preliminary findings from a U.S. Food and Drug Administration rodent study, which found that when retinyl palmitate-laced creams are applied to the skin and exposed to sunlight, they may speed the development of skin tumors and lesions. Even the lowest concentration tested—about 0.1 percent vitamin A—seemed to have this effect.

What should we do?

The EWG called for more research, and advised consumers to avoid products containing the vitamin until scientists determine that it presents no health risks. Vitamin A is an essential nutrient for eye health and more, but it does have a history of safety concerns. At high doses, retinol can cause birth defects, and FDA scientists found that women who use retinol-spiked creams could get enough vitamin A to exceed safe daily limits.

Before you pull products from shelves, though, consider this: “The Environmental Working Group based its [recent] criticism on an unapproved 10-year-old study on mice that has never been published in a journal,” says Doris Day, MD, a New York–based dermatologist. “The group faults the FDA for not releasing the study, but the FDA didn’t release the study because it hasn’t gone through proper peer review.” (A decade may be the world record for longest peer-review period, but that’s beside the point.)

I called on Day for balance. In previous conversations, I’ve found that although she’s a member of the conventional medical community, she also seems to appreciate natural options. What she seems not to support, however, is the FDA’s research methodology and the EWG’s ultimate conclusions on vitamin A. “Mice are not the best representatives of humans,” Day says. “Those mice are bred to grow tumors in an accelerated way. That’s why those mice are genetic mutants.”

The bottom line, according to Day: Vitamin A is innocent until proven guilty. “To date, there’s no scientific evidence that vitamin A is a carcinogen in humans,” she says. “And there’s some evidence that vitamin A is protective against skin cancer. We know it promotes skin-cell turnover. When your cells turn over in a healthy way, they don’t stay in that immature phase, which is ultimately what skin cancer is.” Day continues to prescribe retinyl palmitate, retinols, retinoids and other vitamin-A derivatives to repair the skin of patients with severe sun damage.

Still confused about vitamin A? Look for the FDA’s final report on vitamin A and sunscreens, which is scheduled to be released early next year.