Just before Junko prompted me to look at tretinoin safety, several comments were left on a post about another vitamin A ingredient, retinyl palmitate, saying I needed to update my information (a later listing in our ingredients database is more complete) because "this ingredient is known to cause cancer in lab rats and it's being used in most sunblock products". Retinyl palmitate , sunscreen and skin has indeed been in the news recently. So what's been going on and should we sound A for Alert?

The main reason that retinyl palmitate (RP) caught the news headlines earlier this month is that Senator Charles Schumer urged the Food and Drug Administration to publish its findings on RP. The FDA has been reviewing data from several studies on a potential link between retinyl palmitate and cancer risks since July 2009, but has yet to issue any rulings or guidelines.

In May, the EWG issued press releases calling on the FDA to act because RP is a common sunscreen ingredient. Specifically, the FDA research teams have been looking at what happens to RP in UV light, regardless of what it is formulated in. However, the researchers note that it is an ingredient that is increasingly used in cosmetics.

A 2005 study on mice by the FDA's National Center for Toxicological Research to evaluate the photomutagenicity of RP in cells when exposed to ultraviolet A (UVA) light concluded: "These results suggest that RP is photomutagenic in combination with UVA exposure in mouse lymphoma cells." A year later in 2006, another study, concluded: "Our results demonstrate that, similar to irradiation with UVA light, RP can act as a photosensitizer leading to free radical formation and induction of lipid peroxidation following irradiation with UVB light."

Another research team failed to replicate these results on hamsters (although they specifically looked at the ovaries) and concluded there was no evidence that RP is toxic. The only thing is that they conducted the research for L'Oreal.

There is some – as far as I know – independent research that may contradict the 2005/6 research. But it goes back to 1999 and says that "topical application of retinol does not result in changes in constitutive plasma levels of retinol and, therefore, does not increase the risk for developmental toxicity. (source)

Even more confusingly, there are 2003 and 2005 studies that showed that topical application of RP acted as a sunscreen at 2% concentrations, protecting the skin from UV damage (source).

In 1987, the Cosmetic Ingredient Review Expert Panel (a body that is funded by the cosmetics industry) found that retinol and retinyl palmitate were safe as cosmetic ingredients "in the practices of use and concentration ranges used (up to 13%)". And they have basically been sticking with that story ever since. The CIR recently changed its name to The Personal Care Products Council and has been quick to say that EWG has pounced on sunscreens even though the FDA's research is on RP and sunlight, regardless of what it is formulated in.

The EWG may not have done itself a favor by creating a link between RP safety in sunlight and its own controversial report on sunscreen safety. A search on Truth In Aging threw up very few examples of RP present in sunscreens – a notable exception being Murad. It does crop up, however, in cosmetic products that happen to also contain a sunscreen, although that's not their primary role (eg KaplanMD's Lip 20).

For the time being, I'm going to keep my council until the FDA publishes its findings.