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Great Health Delusions - Sunscreens, Sun Exposure, Cancer
All around the world government agencies mount huge advertising campaigns promoting the idea that sun exposure causes skin cancer and that sunscreen use protects you from the sun's harmful rays.
However the scientific evidence supporting the use of sunscreens to prevent skin cancer is weak. Sunscreens have been shown to be ineffective as UV blocks and many ingredients have been shown to be potentially hazardous and carcinogenic.
How can these promotions campaigns be justified and supported? What is the evidence? What should you believe?
Lets look at some of the claims and counter-claims. The major source of in formation for this is the recently published report (EWG 2010 Sunscreen Guide) (EWG 2010).
Sunscreens Ineffective Especially When not Applied Often Enough
There is recent research claiming a direct link between UVA exposure and damage to the DNA of human melanocyte skin cells.
However, the poor inherent ability of melanocyte cells to repair damage, leading to high mutation rates, appears to be the major cause and these mutations can occur in cells in areas of the body not exposed to UVA.
Sunscreens Don't Work
Many Sunscreens that people are using:
- simply don't work
- are not being used properly in terms of amount and frequency
- don't provide the claimed level of protection, and
- contain hazardous ingredients.
This means that people are deluded into a false sense of security that the sunscreens they are using will provide the claimed protection from UVA and UVB.
Using the analogy of an umbrella - most umbrellas are leaky letting some light pass through, the plastics used releases harmful chemicals and people don't use them often enough. You are deluded into believing the umbrella offers total protection and so you go out into the sun for much longer periods of time and during the middle of the day, when you would otherwise not do so. The net effect of umbrella use may be negative, compared to:
- not going out into the sun without a hat or protective clothing,
- reducing your time spent out in the sun without protection
- your total level of protection against cancer and other health hazards. The reduction in UV exposure may be offset by the exposure to harmful ingredients and the lack of vitamin D.
The delusion is summarised as:
- Users spend more time in the sun during the peak danger times because they believe sunscreens offer the claimed level of protection. The net effect may be to increase the UV exposure.
- The research that sun exposure causes melanoma and that sunscreens prevent cancer is unconvincing in both respects, and the major health authorities have not provided definitive advice.
- Users are unaware that some of the ingredients are hazardous and may cause cancer and other health issues.
- By screening out UVB users may not produce adequate amounts of Vitamin D from sun exposure and this may cause other problems including reduced ability to control other cancers unrelated to sun exposure.
Why Sunscreens are Ineffective
Below is a summary of some of the issues:
- EWG 2010 only recommended 39 of 500 (8%) of the beach-goer and general sports sunscreens for this season. The 39 beach and sports products that were given the 'green' rating for safety and effectiveness all contain the minerals titanium or zinc.
- The major choice around the world is between 'chemical' and 'mineral' sunscreens. The protective ingredients may have poor stability when applied to the skin, are absorbed and may disrupt the hormone systems and cause other effects. The 'mineral' based sunscreens (titanium and zinc), are often included as micro-sized or nano-scale particles because they provide strong UV attenuation, but they are transparent when applied to the skin. Note: the use of aluminium ingredients has declined because of safety concerns. Recent research has raised concerns that the tiny metal particles are hazardous because they may be absorbed through the skin and damage cells. A study reported in Scientific American showed that nano-titanium dioxide caused cellular damage to bacteria. Other studies have shown that soil bacteria are damaged by copper oxide, silver and zinc oxide nanoparticles, that are also used in sunscreens and other products. High-SPF products contain greater amounts of sun-blocking chemicals than low-SPF sunscreens.
- Many SPF claims were very exaggerated. Products with advertised high SPF ratings, create a false sense of security about protection. Many people that use often stay exposed to the sun longer, go out in the sun during the high risk times of the day and still get burned. Products with false SPF claims may provide very poor protection against UVA radiation.
- The history of hazardous chemical use in sunscreens has not been good. The ingredient PABA was shown to damage the DNA in human cells, and it was banned as a sunscreen ingredient several years after these results were published.
- Recent research has raised concerns about a form of vitamin A called retinyl palmitate, that EWG 2010 found in 41 percent of sunscreens. This ingredient is added as a skin moisturizer and general skin tonic, rather than as a UV screen. FDA data suggests that vitamin A may be photo-carcinogenic, which means that when exposed to UV rays on your skin, the compound and skin undergo complex biochemical changes and become hazardous. EWG 2010 recommends that people choose sunscreens that are vitamin A-free.
- EWG 2010 found that oxybenzone, that is known to be absorbed through the skin and disrupt hormone function was found in about 60 percent of the 500 beach and sport sunscreens tested.
- Few people apply enough sunscreen, and re-apply it often enough, to benefit from the SPF protection promised on the label. Studies found that people typically used about 25 percent of the recommended amount.
- A major cause of the uncertainty about the safety and effectiveness of sunscreens in USA lies with the FDA, which has not finalized sunscreen regulations it has promised since 1978. FDA officials estimate that the first federally regulated sunscreens will not be on the shelves before the summer of 2012.
- Too little sun exposure might actually be harmful, reducing the vitamin D levels in the body. The main source of vitamin D is that made by your own body when your skin is exposed to sunshine. Vitamin D is vital for your health. It strengthens your bones and your immune system, reducing the risk for a various other cancers (including colon, kidney, breast and ovarian cancers). The use of sunscreen with a sun protection factor (SPF) of 8 has been shown to reduce Vitamin D production by more than 95%. There has been an increase in the incidence of Vitamin D deficiency in Australian and New Zealand which may be related to the success of their 'Slip, Slop, Slap' campaigns to reduce sun exposure. Experts disagree on the ways to get enough sun exposure for adequate vitamin D production without increasing skin cancer risk.
- There are may claims that free radicals and various other skin-damaging ingredients of sunscreen may also be hazardous. The free radicals may be generated by UV radiation or produced by the ingredients themselves, may damage DNA and skin cells, and accelerate skin aging and cause skin cancer.
Why is there so little definitive information about sunscreens, sun exposure and skin cancer?
There are four main reasons:
- The use of sunscreen tends to increase the amount of time people spend exposed to the sun, including poorly covered sites such as the trunk and legs.
- The first sunscreens developed did not provide significant or adequate protection for UVA and especially UVB protection, and so the research related to inferior products.
- There is a huge variety of sunscreens of varying effectiveness, and the application practices and frequency of use also varies. The sunscreen practices in the groups studied may not have been consistent enough, including the use of adequate amounts or body coverage, to provide the protection from melanoma.
- The damage that is believed to cause melanoma my have occurred in childhood and there may have not been enough time for the benefits of modern sunscreens to be demonstrated.
The published studies provide contrary evidence on the effectiveness of sunscreens in reducing the risk of melanoma. Studies in France, Germany, Austria, Sweden, Belgium and New York state showed and elevated risk of melanoma with sunscreen user. However, studies in Brazil, Spain and California report decreased risk of melanoma. In 2000 the IARC ( International Agency for Research on Cancer) assessed 15 studies on sunscreen and melanoma and found conflicting results with 8 studies finding significantly higher risks, but with 3 studies showing significantly lower risks and 4 studies reporting no effect. No conclusion could be made and the working group issued a warning that sunscreens should not be solely relied on for UV radiation protection.
You need to make up your own mind up about how reliant you can to be using a sunscreen. Read the labels and avoid ones with hazardous ingredients. Read the reports on which products are recommended. Don't solely rely on sunscreens. Most authorities now recommend clothing, hats and limited exposure times during the middle of the day.
© 2010 Dr. John Anderson