More on Sunscreen and Cancer

by Shara Evans on May 24, 2012

The following post is by Jessica Skiba.  Jessica has just completed her first year of studies at the University of Michigan School of Public Health in the Epidemiology Department. Her main research focus is genetics, with interests in cancer and infectious disease. She is currently completing her  summer internship at the Center for Public Health and Community Genomics with Dr. Toby Citrin from the Health Management & Policy department.

A recent internet article caught my attention- sunscreen causing skin cancer? Say it can’t be so, for the irony is almost too much for me to handle. As I am a former competitive swimmer, I spent a great majority of my youth outdoors and poolside. I would be at our local outdoor swimming pool from the time practice started early in the morning until dinner time. But I was also an avid sunscreen user, for my mother had it drilled in my head at a young age that I, a light-haired and fair-skinned kid, needed to lather on the sunscreen prior to getting in for practice. Even to this day, I am usually the first of my friends to lather up if we are headed to the beach or somewhere sunny. But have I been actually adding to my risk of skin cancer instead of reducing it?

Image Credit: http://www.skincancer.org/prevention/sunbur

It does make sense that sunscreen would be involved with skin cancer because sunscreen is used when a person is exposed to a known risk factor for skin cancer, sunlight. Clearly epidemiological studies have supported that sunscreen use has been associated with a decrease in melanoma incidence, but it might not be simply the choice to lather up or not that actually plays a role in increasing the risk for skin cancer.   The Environmental Working Group (EWG) released its annual report on sunscreen recommendation, and the results aren’t too sunny for sunscreen companies. The report only recommends 8% of beach and sport sunscreens. Only a whopping 39 out of 500 analyzed passed the test, due to exaggerated protection claims and potentially harmful ingredients.

Skeptics of sunscreen have previously argued that use of sunscreen will inhibit the production of vitamin D in the skin, but it is possible to prevent inadequacies through consuming a diet rich in fortified foods.  But according to EWG, the culprit behind the recent exposure incident is vitamin-A, which is found in 41% of sunscreen as retinyl palmitate. The irony continues, as this ingredient is used in sunscreen as an antioxidant to the aging of skin and is also used in various beauty and night creams. Adding more to the confusion is that consuming foods rich in vitamin A is considered to be healthy, as it plays a part in immune function, vision, and cellular communications, among other roles. Even deficiencies in vitamin A can be a serious health concern, especially in infants and pregnant women in developing countries.  But the same is not true in terms of health of your skin in sunlight.

The Food and Drug Administration (FDA) in conjunction with the National Toxicology Program (NTP) released a joint report in December of 2010 titled “Photococarcinogenesis Study of Retinoic Acid and Retinyl Palmitate.” The report suggests that retinyl palmitate may increase risk of skin cancer when the compound is used on sun-exposed skin.  The study of concluded that retinyl palmitate enhanced the photocarcionogenicity activity of broad-UV spectrum light and UVB in mice, citing earlier onset and an increase in number of skin lesions and squamous cell tumors.

Image Source: http://breakingnews.ewg.org/2012sunscreen/sunscreens-exposed/the-problem-with-vitamin-a/

Another challenge is the label of “babies” or “children” on some 65 sunscreen packaging that also contains retinyl palmitate. Skin cancers often require repeated exposure to lead to genetic changes responsible for tumor growth. By starting exposure at a younger age, the possibility for skin cancer may increase.  The EWG thus recommends avoiding vitamin-A containing sunscreens.

Image source: http://www.skincancer.org/prevention/sun-protection/sunscreen

Yet on the EWG website, it is mentioned there is a lack of definitive research to pinpoint whether vitamin-A actually does increase cancer risks.  Marie Jhin, MD, a clinical instructor at Stanford University and dermatologist stated, “As far as I know, there is no definitive research stating that topical vitamin A causes skin cancer,” but recommends “more physical sunblocks that don’t contain large amounts of vitamin A anyway.”  The Skin Cancer Foundation also stands its ground on the importance of sunscreen use because the study performed by the FDA has yet to complete peer review and has yet to be published. The SCF also questions whether the trace amounts of retinyl palmitate found in sunscreen is actually carcinogenic in humans, as there is a lack of scientific evidence to illustrate the harm

This summer I will still go to the pool, but I’ll be sure to wear my UV-blocking sunglasses, bucket hat, and sunscreen. I realize sun protection is essential to prevent skin cancer, so I’m still going to use my tried and true sunscreen, which coincidentally does not contain any vitamin A.

Sources:

http://tlc.howstuffworks.com/home/sunscreen-giving-you-cancer.htm

http://www.nytimes.com/2012/04/24/science/sunscreens-and-vitamin-d.html

http://ods.od.nih.gov/factsheets/Vitamina-HealthProfessional/

http://breakingnews.ewg.org/2012sunscreen/sunscreens-exposed/executive-summary/

http://ntp.niehs.nih.gov/?objectid=AC4AD14D-F1F6-975E-7834500D3DE5CEF0

http://www.skincancer.org/prevention/sun-protection/sunscreen/if-recent-attacks-on-sunscreen-concern-you

 

 

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