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Directorate-General for Health and Food Safety
4.1 Can sunbeds cause any other health effects besides cancer?
UV radiation has been proven to have an immunosuppressive effect and it is clear that UV- (both UVA and UVB) induced suppression of skin immunity plays a role in the development of skin cancer. Besides its effects on the skin, UV irradiation can also influence immune reactivity in different internal organs that play an important role in immunity.
Exposure to UVA as well as to UVB also speeds up photo-aging and wrinkling of the skin damaging collagen and elastin.
Sunbeds are claimed to have beneficial effects because they can induce production of vitamin D. Indeed, the fraction of UV-B emitted from sunbeds can induce vitamin D production; however, the increase of UV-induced vitamin D production is limited and will not increase after it has reached a plateau. Professional and public health organisations in several countries worldwide do not recommend the use of sunbeds to enhance vitamin D levels even in winter. Stimulating the production of vitamin D by exposing just the unprotected face, arms and hands to natural sunlight for about 15 minutes a day, depending on latitude, season and daytime, combined with a balanced diet should provide for sufficient levels of vitamin D. If this proves to be deficient, public health authorities in some countries at northern latitudes recommend dietary supplements. Some sunbed users claim that sunbed use boosts their moods, because they feel better about themselves with a suntan or they have the chance to relax at the sunbed salon, and there is some evidence that these effects make some people feel they ‘need’ to use sunbeds. It is yet unclear whether the UV exposure-seeking behaviour is a psychological/behavioural phenomenon or whether this has a biological basis. Cultures of skin cells exposed to UVB have shown increased expression of beta-endorphin, which is the body's natural pain reliever and produces feelings of pleasure.
Another temporary effect of UV-A exposure, is that blood pressure levels seem to be lowered for about 30 minutes following sunbed use. This does not seem to have any accumulative or longer lasting effect.
Exposure to UV radiation may cause a range of eye conditions and may trigger the early onset of diseases normally linked with ageing such as cataract and age-related macular degeneration (AMD).
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4.2 What is the immunosuppressive effect of UV?
An immunosuppressive effect slows down the activation or the efficiency of the immune system. Dermatologists have known for some time that UV radiation has an immunosuppressive effect and have used it to treat inflammatory skin diseases and contact allergies. Clinical dermatologists have also known for some time that skin cancers in patients taking immunosuppressive medication (prescribed after transplantations, for example, to reduce the risk of rejection) almost entirely originate in the currently or previously UV- exposed skin areas.
One of the mechanisms for this effect is via the T lymphocytic cells. Exposure to UV upregulates several other factors involved in immunosuppression, which may explain how this effect occurs in both the UVB and the UVA wave range although the mechanisms for this effect might be different. The Langerhans cells in the skin (cells that take up antigens, and process them towards activation of immunity) are also a target of UV irradiation. These cells can be damaged by UVR and can cause them to migrate away from the skin.
The role of UVB in immunosuppression is well established in mice and humans, but until recently, the role of UVA was less clear: now there is evidence of a positive interaction of UVB and UVA in human immunosuppression. The optimal wavelengths of the immunosuppressive action by UVB appear to be around 300 nm and for UVA around 370 nm, which is particularly significant because that is in fact the predominate emission of UVA from sunbed lamps. The effects are dose dependent: the immunosuppressive effect of UVA was apparent at doses in the range 300 to 1000 J/m2, but disappeared at higher doses according to one study cited in the Opinion. According to another study the Opinion refers to, exposure to longwave UVA (340- 400 nm) strongly down-regulated genes involved in antibacterial and antiviral defence.
