Is sunscreen causing more free radical damage to your skin?

By Dr Des Fernandes

Research work done at Riverside Laboratories in California on sunscreens over the last couple of years has exposed the alarming information that three of the most popularly used organic sunscreens for UV-B in the USA and most of the world (octylmethoxycinnamate, octocrylene and oxybenzone) do not remain on the surface of the skin, but are absorbed.

We know that most sunscreens are absorbed through the skin – there is no reason to suppose that they are not absorbed. Of course, the higher the SPF, the stronger the concentrations of these sunscreens will be.

The alarming part of the discovery was that these sunscreen agents create even more free radicals when they are absorbed into the skin and are struck by a UV ray. They have, in effect, saved us from one UV ray only to become a serious free radical deeper in the skin. We have for a long time realised that when a chemical absorbs UV rays, there is a change in the energy of that molecule which can result in the formation of free radicals. If the free radical is on the surface of the skin then we don’t need to worry about it too much. However, when the free radicals occur in the depth of the skin they then set up chain reactions of free radical destruction and can do significant harm.

The researchers at Riverside covered skin with a variety of popularly used sunscreens in the USA and then exposed the skin to UV light. They then measured the level of free radicals in the skin and compared the results to what they found when they did not apply sunscreens to skin and then exposed the naked skin to an equivalent amount of UV light. The shocking thing was that there were fewer free radicals in the skin that had not been covered with a sunscreen.

Translating this information into real life, people look for a high SPF sunscreen because they believe that they will be better protected when they are exposed to sunlight. What they don’t realise is that this high SPF product is laden with organic ingredients that are destroyed when they react with UV light and in many cases the resultant molecules are free radicals. Because the high SPF requires higher concentrations of these ingredients, this then means that more molecules are absorbed into the skin after one applies the sunscreen.

Because people feel they are well protected by a high SPF product, they tend to stay longer in the sunlight because they are not experiencing the burn that UV-B rays would give them. In many products without real broad spectrum UV-A protection, UV-A rays pass into the skin un-filtered and tend to create free radicals in the dermis.

In the initial stages, one only experiences the benefit of UV protection. The skin does not turn red, but while the molecules that remain on the surface are busy blocking UV rays, they are also being inactivated. That’s why the skin starts to burn and people suddenly realise they should get out of the sun, but it’s too late! While they were in the sun, more UV rays penetrate into the skin and if they encounter a sunscreen molecule in the depths of the skin, they react and free radicals are generated which leads to a chain reaction and many surrounding cellular structures and essential chemicals are affected. If the DNA is affected by the free radicals then mutations may occur that can lead to skin cancer at a later date.

On the other hand, the person who did not apply a sunscreen feels the energy of the UV-B rays within about 20 minutes and becomes uncomfortable enough to seek shade. They will have received UV-A irradiation just the same as the people who used sunscreen. If a very good protective sunscreen were used with UV-A four-star rating then about 60-70 per cent of the UV-A rays would enter the skin and cause proportionally less free radicals. However, they would not have to contend with the free radicals generated by the absorbed sunscreens.

The researchers raised the possibility that the free radicals generated by sunscreens themselves may account for the fact that since the introduction of sunscreens, the incidence of skin cancer in the USA has risen. There are other explanations for this, but no one knows for certain why the rates have increased.

I firmly believe that every sunscreen should have minimal quantities of organic sunscreens and rely more on the stable forms of the inorganic sunscreens. The problem is these sunscreens tend to make the skin rather pasty because the inorganic ingredients like titanium dioxide and zinc oxide leave a visible trace at higher concentrations.

However, we need to understand there is no such thing as a total block. Every sunscreen allows UV rays through to a varying degree and the difference between an SPF 16 and SPF 45 is not really more than one to two per cent at most.

Titanium dioxide or zinc oxide remains on the surface and are not affected by sun exposure as much as the organic sunscreens — and this keeps the SPF value for a longer time. The only problem is that they can be rubbed or sweated off. When there is adequate protection, the organic molecules that have been absorbed deeper into the skin are exposed to fewer UV rays and so fewer free radicals develop.

I believe that every sunscreen should address the free radical issue by including antioxidants that mop up as many as possible of the incidental free radicals that occur. I repeat, no sunscreen can prevent 100 per cent of solar rays so free radicals will always occur even with the best, strongest sunscreen after only a short exposure.

Look for a sunscreen that provides the following:

1. Real SPF 15 to 20 when used under normal circumstances, not laboratory conditions.
2. Restricts exposure to organic sunscreen molecules that cause free radicals when they have been absorbed. We should avoid oxybenzone and reduce amounts of octocrylene and methoxycinnamates.
3. Gives surface protection with inorganic sunscreen (titanium dioxide which won’t interfere with the activity of the antioxidants whereas zinc oxide can). This surface protection means the absorbed organic molecules are less exposed to UV rays.
4. Significantly reduces activity of free radicals because of the included antioxidants.
5. No perfumes to cause photosensitivity.

Always remember to re-apply every one and a half to two hours because SPF 15 to 20 does not give you protection for long enough. Please remember that SPF 15 equals 150 minutes (about two and a half hours for Fitzpatrick type II) to about 300 minutes (about five hours for Fitzpatrick type IV) under ideal circumstances.

For more information contact Sensa Skincare on 1300 888 708.

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