Sunblock: Good or bad?

By: David Hassan

Should you be thinking twice before you lather your child in sunblock at the beach? These are the some of the stirrings that I have been hearing lately about sunblock. One recent development is the use of nanoparticles. Remember zinc back in the 80s on all of those cricketers? This worked as an effective barrier against harmful sunrays, but, alas, it was too sticky and hard to apply for the public to get into wholeheartedly. The reason for this was the zinc particles were too big. Nanoparticles of zinc and titanium have recently been created to solve this problem – allowing for easy application and leaving the skin soft and smooth.  But are they too small? Do they get into your body, producing toxic effects?

The answer is probably not. Scientific studies to date that have looked at nanoparticle absorption by applying nanoparticles to the skin for a period of time and then performing a skin biopsy to see how far the metals have gotten through, show that they stick to the outside layer of the skin. They are not absorbed far at all.

Another concern is vitamin D. This is a vitamin that we get from the sun. If adequately applied, most sunscreen is good at blocking vitamin D absorption. In theory, this could be a problem leading to thin bones and premature fractures. But population studies have not shown this to be an issue in real life. However, if your skin is of the type that always wearing sunblock is a must, then taking vitamin D supplementation is recommended.

One final concern that I am interested in are coral reefs. Could sunblock leaking from happy snorkellers be killing the reefs? Sunblock concentrations have been measured in aquatic ecosystems around the world, and some have been shown to harm coral in the lab environment. This question needs to be answered quite urgently, but there is not enough information yet to say one way or the other.

So, overall, there are some interesting and potentially concerning issues with sunblock. However, balanced against the harmful effects of ultraviolet rays that are known to cause such things as skin cancer and sunburn, safe use of sunblock still wins out for me. It is still an important part of the advice I give my patients. However, do not forget those other sun-protective measures, like staying out of the sun in the hot part of the day and wearing protective clothing and sunglasses.

By Dr David Hassan,
Skin Cancer Doctor, SunDocs


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