Ask Pablo: Does Sunscreen Cause More Skin Cancer Than It Prevents? (Updated)


Image credit: kweezy mcG/Flickr

The original Ask Pablo article answering this question was very popular and the Environmental Working Group has just published its 2010 Sunscreen Guide. Since summer is right around the corner, this topic is more relevant than ever. The following article is completely updated based on the findings of the 2010 report and also takes into account reader feedback to the previous article.


Dear Pablo: I have heard that sunscreen actually causes more skin cancer than it prevents. Is there any truth to this?

It sounds unbelievable but there is actually some truth here. The Environmental Working Group is releasing their 2010 Sunscreen Guide, in which they independently tested 1400 SPF-rated products, including beach and sports lotions, sprays and creams, moisturizers, make-up and lip balms. Only 8% of the beach and sport sunscreens (39 out of 500) offer sufficient protection and healthier ingredients to earn the EWG's "green" rating. There are two main concerns about sunscreen; the false sense of protection that they offer, and the chemicals that they contain. Does Your Sunscreen Have You Covered?
The sun produces a wide spectrum of light, including the three bands of ultra-violet light that we call UVA (400-315 nm), UVB (315-280 nm), and UVC (280-100 nm). UVB is the band of light that causes sunburns and the only category of UV that sunblock is regulated for by the US FDA. Unfortunately for us, UVB represents only 4% of the UV radiation entering the atmosphere. UVA is primarily responsible for causing skin cancer, premature skin aging, and other skin damage. Since UVA protection is not regulated by the FDA, many claims of UVA protection are not credible. Either the UVA protection is insufficient, or the active ingredient degrades too rapidly when exposed to sunlight, leaving you with inadequate protection after some time.

High SPF products, which protect against sunburn, often provide very little protection against UVA radiation.

Quiz: Are You a Green Beauty?
What Does SPF Mean Anyway?
The SPF, or Sun Protection Factor, is a laboratory-based measure of the skin damage caused by UVB with sunscreen use relative to without protection. As with most theoretical measures, the empirical results don't match up. Many variables affect the performance of sunscreen, including skin type, activity (particularly sports and water activity), application quality and reapplication frequency, amount absorbed by the skin, and the degradation of active ingredients by UV.

Few people use enough sunscreen to benefit from the SPF protection promised on the label. Studies show that people typically use about a quarter of the recommended amount. Because sunscreen effectiveness drops off precipitously when under-applied, in everyday practice a product labeled SPF 100 actually performs like SPF 3.2, an SPF 30 rating equates to a 2.3 and SPF 15 translates to 2. Moreover, FDA scientists say SPF claims above 50 cannot be reliably substantiated.

Carcinogens and Hormone Disruptors In Your Sunscreen?
Some sunscreens, like Panama Jack Naturals Baby Sunblock SPF 50 contain oxybenzone. Oxybenzone is used because it blocks UVA and UVB but it gets absorbed into the skin, acting as a photosensitizer. Because of this it is believed to be a likely photocarcinogen. As if that weren't enough, oxybenzone is also a hormone disruptor that has been found in the urine of 97% of Americans over the age of six (CDC). Fortunately there has been a decrease in the use of oxybenzone but it is still approved by the FDA for use in sunscreen.

Recently available data from an FDA study indicate that a form of vitamin A, retinyl palmitate, when applied to the skin in the presence of sunlight, may speed the development of skin tumors and lesions (NTP 2009). This evidence is troubling because the sunscreen industry adds vitamin A to 41 percent of all sunscreens.

What Can You Do To Protect Your Family?
In order to protect yourself and your loved ones from the sun and the unintended consequences of using some sunscreens here are a few suggestions.
  • More is not better: Sunscreens rated with SPF 55-100+ block just 1-2% more sunburn rays than an SPF 30 rated sunscreen. They offer a false sense of protection and their effective SPF for UVA might be as low as 9.3 as with Banana Boat Baby Max Protect (SPF 100).
  • Check your sunscreen: Find your sunscreen here and dispose of it properly if it doesn't pass muster.
  • Sunscreen loses its effectiveness. Check the manufacturer's date stamp and replace if it is expired.
  • Check here for additional ingredients to avoid
  • When you buy sunscreen follow Environmental Working Group's list of recommended sunscreens.
  • Look for sunscreens with avobenzone, Mexoryl, titanium dioxide, and zinc for UVA coverage.
  • Avoidance is best. If you don't have to be out in the sun between 10am and 4pm, stay in the shade.
  • The best sunscreen is the kind you wear. Outdoor clothing manufacturers are producing SPF-rated clothing to keep you comfortable and sunburn free.

Still want to learn more? Read the Full Report.

Pablo Päster is a weekly columnist for TreeHugger.com, an experienced greenhouse gas engineer and the Senior Environmental Program Manager at Hara Software. Send your questions to Pablo(at)TreeHugger.com or submit the via this form and connect to his RSS feed.
More Resource On Sunscreen:
How to Go Green: Natural Skin Care
Last Call For Sunscreen
Lycomato's Ingestible Sunscreen Based on Tomatoes So You Don't Turn Into One
Why We Need Safer Sunscreen
Face Off: Our Sunblock & Sunscreen Picks

Tags: Cancer | Cosmetics | Toxins

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