Should you use 30+ spf sunscreens?

Feb 24, 2012 by

high spf sunscreens

I think we all understand that exposure to the sun is the biggest cause of wrinkles. The brown leather wrinkled look is a high price to pay for the sun-kissed tan of our youthful skins. As I grow older I find myself more and more careful about the sun. I look at areas on my body that have never been exposed to the sun versus my arms or legs and the result is plain to see. In fact the areas that have never seen the sun are remarkably young looking which makes me wish I had always been so careful.

So investigating how to protect myself from the ravages of the sun I decided to do some research into sunscreens. What a can of worms I opened! I had not realised just how much controversy there is in the scientific community regarding the use of chemicals in sunscreens. They have been blamed for:
• Increased rates of cancer, in particular, melanoma
• Vitamin D deficiency by inhibiting its production in the body
• Speeding up the growth of cancerous tumours
• Disrupting sexual development in young people and sexual function

The main culprits are retinyl palmitate for increased cancer risk and oxybenzone which may be a ‘hormone disrupting’ compound. However there is such disagreement in the scientific community as to whether any of these claims have actually been proven (most studies were done on mice) it is very difficult for the layman to understand the true risk. Not helping is the fact that government regulated standards as to what chemicals can be included in sunscreens varies between countries.

Apart from potentially damaging chemicals another major concern is that people may misunderstand exactly what any given spf or sun protection factor actually means. Sun protection factor is used to give some kind of objective measure to how long we can stay in the sun. It is the following formula:

minutes in the sun x spf = minutes we can stay in the sun

Before a product is given an spf rating the manufacturers have to do controlled tests on humans with each of their products. Note the word controlled in this context. Also it is important to understand that the spf is a measure of UVB absorption and not UVA which is typically about 10% less. Protection against UVA rays is particularly important when fighting ageing of the skin.

In theory if I can stay in the sun for 10 minutes without burning then by using a sunscreen that is spf 15 I should be able to stay in the sun 150 minutes or nearly two hours. However, this is assuming:
- I guess the original 10 minutes correctly
- I put the sunscreen on at 2mg per cm2 even thickness
- I cover all areas to be exposed and don’t miss any bits
- I put it on 15 to 20 minutes before exposure to allow the skin to absorb it properly
- I don’t apply it over moisturisers or other skin care products
- I don’t sweat profusely
- I don’t go swimming

This is quite a long list of things to get wrong and significantly impact my sun protection. Any of these factors will reduce sunscreen effectiveness and will require re-application.

Another potentially misleading fact is that the amount of protection provided by a sun factor does not increase exponentially. So spf 30 does not give twice the protection of spf 15 and the difference between spf 30 and 50 is even less. The actual table is as shown below:

[ws_table id="1"]

Given the alleged concerns already noted in respect of chemicals in sunscreens and assuming that a higher spf is achieved by a greater concentration of chemicals in the product there is a valid argument to not use the higher spf sunscreens. It may be that the benefit of increasing the spf in your sunscreen is outweighed by the higher concentration of chemicals needed to achieve that ‘70’ spf. This is especially true if you follow the guidelines and apply and re-apply a sunscreen properly and are using it daily.

One study published in the Western Journal of Medicine found an increased incidence of melanoma amongst users of high (over 30) spf sunscreens. On further investigation it was discovered that people in the trial were intentionally sunbathing and staying in the sun for longer periods because they were using the higher spf sunscreen. It gave them a false sense of security. The FDA is concerned that higher spf does encourage people to stay in the sun longer than they should and has therefore proposed that spf should be capped at 30+. Judging by the products on the shelves this does not seem to have been adhered to in practice

So what is the answer? Sunlight damage is cumulative and occurs with repeated exposure over time. Even if exposure is limited to brief outdoor lunches or a 20-minute walk, cumulative exposure is enough to cause the signs of skin aging and increase the risk of skin cancer. So just because you are not a sun worshipper does not mean that you don’t have to be vigilant against the sun.

You should always make sure you are using a broad spectrum sunscreen, one that protects against both UVA and UVB rays. Pretty much all products these days protect against both.

If you are concerned about the potentially damaging effects of chemical sunscreens you may like to look for mineral sunscreens which reflect light away from the skin. Titanium dioxide and zinc oxide for example. Even these are not without problems as they can give you that white and pasty look. To avoid that manufacturers have developed micronized mineral sunscreens with very very small particle size. Micronized mineral sunscreens are arguably less effective because they are absorbed into the skin and therefore do not reflect light.

Applied regularly and properly, a sunscreen of your choice with a spf factor of 15 will provide us with the protection we need when outdoors. It goes without saying that hats, long sleeves and staying in the shade is the best protection of all.

Are you concerned about chemicals in sunscreens? Do you use a sunscreen daily?

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