With the northern Hemisphere officially creeping into summer, the first arguments of this season’s sun and skin debate have arisen
Anti cancer councils and organisations akin to Australia’s Sunsmart are continuing their awareness-raising campaigns, educating the public about the issue, and most importantly the practice of sun protective behaviour; although significant investment and persistence are required, well executed and long running campaigns can make significant progress, albeit on a regional scale. But a vocal group of skeptics are continuing to question whether a central element, sunscreen, might just be part of the problem.
A glance at the increasing rates of skin cancer globally, and comparison with the growth of the sunscreen industry and breadth of Sunsmart awareness campaigns has led some to doubt the safety of ‘slopping’ on some sunscreen.
If we’re all so Sunsmart, why is skin cancer still on the rise?
The latest argument is fuelled by research from the University of California in 2006, which found that some sunscreen ingredients could cause an increase in free-radicals, or reactive oxygen species (ROS). ROS are one of the most damaging effects of UV radiation on human skin and a major cause of cell damage, leading to skin cancer.
While the research is undoubtedly interesting, its conclusions are not compelling enough to warrant an industry wide rethink on sunscreen. The research was not carried out to assess exactly what kind of damage the ROS caused, merely that it increased.
And a primary finding from the research was that the ingredients caused this increase in ROS when UV radiation penetrated the top layer of the skin (stratum corneum) and reached keratinocytes that had already absorbed the substances.
The conclusion drawn from this was that proper use of sunscreen, i.e., application prior to going into the sun, and re-application every two hours, would mitigate the risk of increased ROS and deliver safe sun protection.
Another argument brought against modern sunscreens is their use of nanoparticles. The crux of it being that there is not evidence to support the premise that long term use of, or exposure to the nanoparticles used in sunscreen is safe practice that has no effect on human physiology.
“To date, the current weight of evidence suggests that titanium dioxide and zinc oxide nanoparticles do not reach viable skin cells; rather, they remain on the surface of the skin and in the outer layer of the skin that is composed of non-viable cells”
Therapeutic Goods Administration (TGA) February 2010
Although this TGA position statement recognises no risk, it does allow for future data to change this stance.
Perhaps this annual dissection of sunscreen is a reaction to the FDA’s three decades overdue release of sunscreen regulatory guidelines? Alternatively, a largely unregulated sunscreen industry could be evolving and developing so fast that the long term risks and impacts of their practices might not yet be apparent and genuinely are risky or dangerous.
Either way, the questions should begin to be answered, or at least acknowledged, this October when the FDA’s regulations for the sunscreen industry finally see the light of day.
As for the continuing increase in skin cancer incidence, despite the public being more educated and aware than ever? It’s important to remember that skin cancer is largely the result of years of cumulative UV exposure and damage.
Skin cancer is most common in late middle age and can be the result of damage caused during formative years, from birth to the late teens. Awareness campaigns have targeted young people and aim to instill Sunsmart attitudes and behaviour in order to minimise UV exposure and the resultant cumulative damage from an early age.
Only the coming decades will tell, as the Sunsmart generations reach late middle age and live through what are currently the most skin cancer prone years.
References:
http://www.ncbi.nlm.nih.gov/pubmed/19775367
http://www.washingtonpost.com/wp-dyn/content/article/2010/06/17/AR2010061705546.html?hpid=politics
http://www.sciencedirect.com/science
http://www.tga.gov.au/npmeds/sunscreen-zotd.htm
Image reference:
http://www.flickr.com/photos/miamism/3987052493/
