Thursday, October 14, 2010Scientific publications

Sunscreens: what to blame for allergies?

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What is exactly the cause for more and more frequent allergic and photo-allergic reactions due to using sunscreen products? Which substance is the cause? An answer to these questions would improve our cosmetics and our safety against UV radiation. A team of Swedish researchers may provide us with possible answers.

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October 14, 2010
What happens to sunscreens when they are exposed to sunlight? They degrade, and how the skin is affected by those degradation products is the topic of a research made in  the University of Göteborg and in the Chalmers University of Technology; its results were presented in a dermatologist conference in Gothenburg.

What is photocontact allergy?

A hole in the ozone layer and changes in sunbathing habits have led to an increase of the number of skin cancers worldwide. One way of dealing with this has been to recommend using sunscreens, though the more frequent use of these products has also triggered an increase of contact and photocontact allergies to sun protection products.

A photocontact allergic reaction is due to the chemical alteration of sunscreens by sunlight, the body’s immune system then responding by an allergic reaction. The reaction is uncommon, and it is generally due to sunscreens filters. Symptoms are eczema-like rashes that can itch. An obvious treatment is to avoid the substance that causes the allergy. It needs to be identified.

Arylglyoxales: the identified allergens

We know that sun creams pass through the skin into our bodies, but we don’t know what effects they have on us, ” says Isabella Karlsson, doctoral student at the Department of Chemistry at the University of Gothenburg’s Faculty of Science. “ Many of them actually break down in the presence of sunlight. We therefore wanted to look at what can happen to the chemical sun protection agents when exposed to UV rays, and how the degradation products that form affect the skin.

In their study, the researchers came up with an explanation of what happens during this process.
Arylglyoxales, one of the degradation products, turned out to be highly allergenic, ” says Karlsson. “ Which could explain why some people are allergic to creams that contain dibenzoylmethane, one of the UVA-absorbing substances in sun creams .”

Promising results

This has made for a better understanding of the mechanism behind photocontact allergy, which could lead to a product that does not cause allergy, and could determine which sun creams people are most likely to be sensitive to.  But their discovery is already having an impact. The healthcare system has long found it difficult to test patients with suspected photocontact allergy, but thanks to the study a new test is being developed.

We’re just starting to work with various dermatology clinics on assessing the test ,” explains Karlsson. “ So more patients will be able to find out whether they have photocontact allergy, which could help them in their everyday lives and reduce the burden on the healthcare system .”

Source : Science 2.0
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