Don’t Get Burned With Your Sunscreen

Reading time: 6 – 10 minutes

With summer upon us in full force, many people are eager to get out and enjoy some time in the sun. However, prolonged ultraviolet (UV) light exposure poses a threat during summer months. Indeed, for an increasing number of U.S. adults, sunburns are becoming more and more common [1]. Although sunburn can be the immediate result of the sun’s UV rays, repeated overexposure can lead to wrinkles, discoloration and other signs of premature aging of the skin, as well as skin cancer.

Protect yourself from the sun

Sunburn results when the amount of sun exposure exceeds the ability of melanin, the body’s protective pigment, to shield the skin. Using sunscreen regularly is one of the best ways to ensure protection from the sun and avoid skin damage. Sunscreen creates an effective barrier on the skin, absorbing or reflecting the sun’s UV radiation. With all the different sunscreens on the market, have you ever wondered how well your sunscreen works compared to other brands? A recent investigation by the Environmental Working Group (EWG), a non-profit advocacy organization that provides useful health resources to consumers, evaluated 1,620 brand-name sunscreens and found that 60% offer inadequate protection from the sun or contain ingredients with significant safety concerns.

The EWG reviewed of hundreds of scientific studies, industry models of sunscreen efficacy, and toxicity and regulatory information, and developed a rating system weighing four major contributing factors for sunscreen effectiveness and safety:

  • Sunscreen products should provide UVA radiation protection
  • Sunscreen products should provide UVB radiation protection
  • Sunscreen product active ingredients should remain stable in sunlight
  • Sunscreen products should contain few if any ingredients with significant known or suspected health hazards

They then rated the effectiveness of each product and assigned health hazard scores based on the ingredient health hazard scoring system from the EWG Skin Deep database, which pools data on chemical hazards, regulatory status and study availability from government agencies, industry panels, academic institutions and other credible bodies. The EWG has detailed the analysis methodology on their website. A summary of their findings are below.

The broad spectrum: UVA and UVB protection

Sunburn is caused by the sun’s UV rays, specifically UVA and UVB. Although most sunscreens protect from UVB radiation, the majority of the UV light that reaches the Earth’s surface is UVA. UVA radiation is more penetrating than UVB radiation and is linked to skin aging and wrinkling, immune system suppression and possibly skin cancer. Indeed, a recent study suggests that the increased number of cases of cutaneous malignant melanoma — the most serious form of skin cancer that accounts for about three-quarters of all skin cancer deaths — from indoor workers is due to UVA rays passing through windows onto unprotected skin [2]. Last year, less than one-third of sunscreens on the market contained a UVA filter. By summer 2009, more than two-thirds of sunscreens on the market now contain a UVA filter. Despite this increased use, 1 in 9 products that contain a UVA filter fail to provide adequate protection against UVA radiation.

SPF: It’s not how high, it’s how much

SPF or Sun Protection Factor is the measure of a sunscreen’s effectiveness, i.e. how much UV radiation is required to produce sunburn on protected skin relative to unprotected skin [3]. The higher the SPF, the greater the protection from UVB radiation. However, SPF measurement is related to the amount of sun exposure, not the time. In addition, sunscreen protection depends upon other factors such as skin type, amount applied and frequency of re-application. Moreover, SPF is not a linear scale. Contrary to popular belief, SPF 100 won’t provide twice the protection of an SPF 50. Indeed, a recent New York Times article pointed out that the difference in UVB protection between an SPF 50 and and SPF 100 is marginal; SPF 50 blocks 98% of UVB rays while SPF 100 blocks 99% [4]. The EWG study found that SPFs from 55-100+ require 2-3 times more active ingredients compared to SPF 30 sunscreen, many of which absorb into the body. Also, high SPF products don’t necessarily block UVA rays.

Rather than worry about how high an SPF is, what’s important is how much sunscreen you wear. To get the SPF advertised on the bottle, you must use one ounce of sunscreen, which is equivalent to two tablespoons of the lotion.

Breaking down in the sun

Active sunscreen ingredients work by first absorbing the sun’s energy so that it doesn’t penetrate the skin and then releasing that captured energy by breaking apart, reacting with other chemicals in the sunscreen or releasing free radicals. Nearly all active ingredients in sunscreen break down to some extent in the sun, although some are more stable than others. Indeed, some active ingredients stop working effectively in as little as 30 minutes, requiring chemical stabilizers to remain effective. The EWG study found that 661 sunscreens contain ingredients known to break down in the sun with no known stabilizing ingredients in the formulation.


The U.S. Food and Drug Administration (FDA) published proposed amendments to the final monograph for sunscreen drug products almost two years ago, but has delayed finalizing and enforcing its provisions [5]. In the absence of guidelines, sunscreen companies are free to use marketing terms the FDA has said are confusing and sell products that would be considered misbranded if the FDA finalized its guidance. The EWG study found that 45% of sunscreens were labeled with one or more terms the FDA has said are indicative of a misbranded product, terms that are “unacceptable” or terms that could “mislead consumers by inducing a false sense of security”. These terms include:

  • chemical-free
  • non-chemical
  • help prevent skin damage
  • sunblock
  • shields
  • All SPF designations greater than 50

In addition, the EWG identified many more terms that would mislead consumers, including “water proof”, “extended wear”, “all day protection” and “as mild as water”.

The EWG’s comprehensive 2009 Sunscreen Guide enables consumers to find better products, listing 93 recommended products including daily moisturizers, lip balms with SPF, makeup products with SPF and low SPF sunscreens, as well as sun safety tips. In addition to providing consumer tips and product rankings, the EWG website includes in depth information about the research process, the science behind sunscreen and skin cancer, lack of government regulation, and more.

The Environmental Working Group (EWG) 2009 Sunscreen Guide

More than a million cases of skin cancer are diagnosed in the U.S. every year. Remember, every sunburn increases your chances of getting skin cancer [6]. Avoid sun exposure between 10 a.m. and 4 p.m. when the sun’s rays are the strongest. If you must be outside, stay in the shade. Be aware that surfaces such as cement, water or sand can reflect UV rays up toward you from the ground, so you may still need protection even it you’re in the shade. When you use sunscreen, apply generous amounts; be sure to cover your face, nose, ears and shoulders. Reapply sunscreen every to to three hours, even if it’s waterproof. Lastly, buy a new bottle of sunscreen each season to ensure maximum effectiveness.


  1. Centers for Disease Control and Prevention (CDC). Sunburn prevalence among adults–United States, 1999, 2003, and 2004. MMWR Morb Mortal Wkly Rep. 2007 Jun 1;56(21):524-8.
    View abstract
  2. Godar et al. Increased UVA exposures and decreased cutaneous Vitamin D(3) levels may be responsible for the increasing incidence of melanoma. Med Hypotheses. 2009 Apr;72(4):434-43. Epub 2009 Jan 19.
    View abstract
  3. Sunburn Protection Factor (SPF). U.S. Food and Drug Administration. Updated 2009 Apr.
  4. Rulemaking History for OTC Sunscreen Drug Products. U.S. Food and Drug Administration. Updated 2009 Jun.
  5. Confused by SPF? Take a Number. New York Times. 2009 May 13.
  6. Dennis et al. Sunburns and risk of cutaneous melanoma: does age matter? A comprehensive meta-analysis. Ann Epidemiol. 2008 Aug;18(8):614-27.
    View abstract
About the Author

Walter Jessen, Ph.D. is a Data Scientist, Digital Biologist, and Knowledge Engineer. His primary focus is to build and support expert systems, including AI (artificial intelligence) and user-generated platforms, and to identify and develop methods to capture, organize, integrate, and make accessible company knowledge. His research interests include disease biology modeling and biomarker identification. He is also a Principal at Highlight Health Media, which publishes Highlight HEALTH, and lead writer at Highlight HEALTH.