So how can you be certain that the skin cancers found were from RP or if that rat would have gotten skin cancer anyways? The answer is you can’t.Īs Dr. Also, these test rats were actually a special breed of rats that were more prone than normal rats to developing skin cancer to begin with! 82% of these special rats that didn’t get any RP on their skin still went on to develop cancer. That’s odd, because if you expect RP to cause skin cancer when exposed to UV radiation, then higher amounts of UV radiation should lead to more skin cancer. In groups of rats receiving the highest amount of UV radiation, there was no difference between animals getting RP vs. One large study done in rats showed that rats with a certain percentage of RP application on the skin and then UV irradiation developed more malignant (read: cancerous) lesions. The truth: Retinyl palmitate (RP), which is the form of Vitamin A naturally stored in human skin, has been called into question because of preliminary data from a series of unpublished studies done by the FDA between 2002-2009. The claim: speed development of skin cancer when exposed to sunlight They found no significant difference in hormone levels between the groups compared to the controls. Interestingly, this one study testing oxybenzone on humans was not reported anywhere on EWG’s website. A study published in 2004 had human volunteers apply oxybenzone containing sunscreen to their bodies daily for two weeks and researchers measured their hormone levels afterwards. What about data looking at the use of oxybenzone in actual humans? What we want is the gold standard in clinical testing: a randomized controlled trial in humans. As the authors write, “…we hope that this analysis helps to place into perspective the doses reported by the in vivo study from which inappropriate conclusions have been drawn and considerable controversy has developed.”īut enough about animal data, which we know is difficult to apply to humans. But another important point to note is just how much oxybenzone were the rats fed? A subsequent study found that it is nearly impossible for a human to apply as much oxybenzone-containing sunscreen to get an equivalent dose of what the rats took in orally (ie a human would have to apply sunscreen to 100% of the body everyday for 70 years straight to take in the same amount of oxybenzone those rats got). First of all, humans and rats (or fish or skin cells grown in dishes in a lab) are VERY different, and extrapolating animal or cell data to humans directly is dangerous and requires further study. One such study showing that rats that were fed this ingredient developed larger uterine weights which was thought to be from estrogenic effects of oxybenzone. People became concerned due to studies done in rats and fish or in skin cells grown in petri dishes showing that oxybenzone affected hormone levels. The truth: Oxybenzone, belonging to a class of compounds called benzophenones, is a UV-A and UV-B filter that has been used in sunscreens since the 1980’s. The claim: acts as estrogen in the body, causes endometriosis in women, lowers sperm count in men So don’t go rushing off to toss your Neutrogena sunscreens in the trash just yet. As a dermatologist in training, I think it’s pretty much my duty to explain the scientific data behind these claims. People are shocked that the EWG names Neutrogena sunscreens as the number one sunscreen to avoid, despite this brand being dermatologist recommended, and the report labels two key sunscreen ingredients, among a list of others, as toxic: oxybenzone and retinyl palmitate. The Environmental Working Group’s (EWG) 2015 Guide to Sunscreen has gone viral these past few weeks, and I have been asked about it by numerous friends who are surprised by the conclusions.
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