At the end of this post I've republished passages from troubling new research findings on sunscreens. But first I want to point out that there are considerable questions raised by various studies about whether sunlight causes skin cancer. From what I've read about the topic in articles for the layperson, the issue is not cut-and-dried. In his 2019 article, The Sun Does Not Cause Melanoma, Dr Leland Stillman stated flatly,
... melanoma rates have been increasing for fifty years, faster than any other cancer, and this is definitely not due to changes in our exposure to ultraviolet-B light.
But he hedges:
One of the most consistent risk factors I was able to identify from the literature on melanoma was intermittent sun exposure, specifically resulting in sunburns. In other words, if you rarely see the sun and, when you do, you get sunburned, then you are maximizing your risk of melanoma.
Yet from an undated unsigned article at Naturalon titled, Compelling Evidence that Avoiding the Sun is Dangerous:
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One of the world’s leading experts on skin cancer, the sun, sunscreens, and melanoma skin cancer risks, doctor Bernard Ackerman, MD (deceased 2008) released an article to the New York Times in July of 2004 where he stated that the link between developing deadly melanoma and overexposure to sunlight was completely unproven. He stated at that time that there was no conclusive evidence that even getting serious burns would lead to skin cancer and no proof that sunscreens protect the body from melanoma and that there was no proof that being exposed to the sun increased the risk of melanoma.
He also cited a Swedish study done in 2000 that concluded that there were higher rates of melanoma in those who used sunscreen compared to those who did not.
A California-based scientist and author, Elizabeth Plourde, PhD, states that malignant melanoma, as well as all other skin cancers, dramatically increased with the use of sunscreens over the past 30 years. She points out that many sunscreens contain toxic chemicals, even chemicals that are known carcinogens.
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I'm afraid that the latest published research findings on sunscreens tend to support Plourde's observations and the conclusion in the 2000 Swedish study:
From Benzophenone Accumulates over Time from the Degradation of Octocrylene in Commercial Sunscreen Products, a research paper by C. A. Downs et al., published March 7, 2021 by the American Chemical Society at ACS Publications.
Abstract
Benzophenone is a mutagen, carcinogen, and endocrine disruptor. Its presence in food products or food packaging is banned in the United States. Under California Proposition 65, there is no safe harbor for benzophenone in any personal care products, including sunscreens, anti-aging creams, and moisturizers.
The purpose of this study was to determine (1) if benzophenone was present in a wide variety of commercial sun protection factor (SPF)/sunscreen products, (2) whether benzophenone concentration in the product increased over time, and (3) if the degradation of octocrylene was the likely source for benzophenone contamination.
Benzophenone concentration was assayed in nine commercial sunscreen products from the European Union and eight from the United States (in triplicate), including two single ingredient sources of octocrylene. These same SPF items were subjected to the United States Food and Drug Administration (U.S. FDA)-accelerated stability aging protocol for 6 weeks.
Benzophenone was measured in the accelerated-aged products. Sixteen octocrylene-containing product lines that were recently purchased had an average concentration of 39 mg/kg benzophenone, ranging from 6 mg/kg to 186 mg/kg. Benzophenone was not detectable in the product that did not contain octocrylene.
After subjecting the 17 products to the U.S. FDA-accelerated stability method, the 16 octocrylene-containing products had an average concentration of 75 mg/kg, ranging from 9.8 mg/kg to 435 mg/kg. Benzophenone was not detectable in the product that did not contain octocrylene. Benzophenone was detected in the pure octocrylene manufactured ingredient.
Octocrylene generates benzophenone through a retro-aldol condensation. In vivo, up to 70% of the benzophenone in these sunscreen products may be absorbed through the skin.
The U.S. FDA has established a zero tolerance for benzophenone as a food additive. In the United States, there were 2999 SPF products containing octocrylene in 2019. The safety of octocrylene as a benzophenone generator in SPF or any consumer products should be expeditiously reviewed by regulatory agencies.
Introduction
Octocrylene (CAS no. 6197-30-4) is one of 14 United States Food and Drug Administration (U.S. FDA) active ingredients approved for use in sun protection factor (SPF) over-the-counter drugs which include sunscreens, moisturizers, lip balms, and anti-aging products. In March of 2019, 2999 SPF products that were registered for sale in the United States contained octocrylene.(1) Octocrylene is also used in non-SPF-labeled personal care products such as shampoos, hair sprays, tanning oils, and conditioners.
The personal care product industry has known for some time that octocrylene is contaminated with benzophenone (CAS no. 119-61-9).
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Here I'll interrupt to ask the obvious question: if the industry knew about that, why didn't the FDA?
You'll just have to finish reading the paper; it'll all come painfully clear in the end.
So what's the best course if you feel you're facing a choice between the possibility of skin cancer from the sun and the possibility of cancer from sunscreen products? I think reasonable advice comes from the article in Naturalon:
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While sunlight may increase the risk of certain types of skin cancer, what is much less publicized is that going without it can greatly increase your risk of other illnesses.
About 50,000 people every year will be diagnosed with either basal cell or squamous cell skin cancer. These are highly treatable and are rarely, if ever, life threatening. Melanoma, on the other hand, makes up for about 10 percent of all skin cancers. If not caught early, it is generally fatal. Much of the information regarding limiting one’s exposure to the sun has been directed at reducing melanoma. There was a recent study released which showed that sunburns in early childhood increased the risk of developing melanoma later on.
But the link between sunlight and melanoma isn’t as clear as you might think. Studies show that habitual exposure to the sun can actually cause the skin to make its own self-protective mechanisms against it. Also, melanoma often forms on body parts that don’t tend to receive much sunlight, such as the soles of the feet.
The balance of evidence strongly suggests that in order to avoid melanoma, it’s important to protect your skin from very intense sun, or sunburns early in life, but just how much protection is not quite clear.
Also, the advice we have been given regarding sunscreen is also open to question as at least two recent studies have shown that using sunscreen is associated with an increased risk of melanoma.
Studies show that just a 10 percent reduction in exposure to sunlight leads to an increased risk of breast cancer by as much as 10 percent and as much as a 12 percent increase in colon cancer.
In light of all these different types of advice and conflicting reports, perhaps it’s best to suggest that we avoid the sun when it’s at its strongest by staying in the shade, staying indoors, or wearing protective clothing, rather than sunscreen.
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