Should solariums carry a health warning?
Visiting a solarium or lying on a sunbed cause the same kind of exposure to ultraviolet radiation as the sunbathing on a hot beach. In the whole population, the dose from solariums is much less than that from the sun, but it is very unevenly distributed, since the exposures of the people who use solariums often are very high. In solariums, there is more of the UV-A radiation with its longer wavelength than in natural sunlight, and that is the type that is less dangerous in theory, but nonetheless the levels of UV-B radiation are still relatively high. Therefore the contributions from both types of UV-radiation to the total erythematous dose are about the same, and it is not at all clear which of them causes more risk.
The most important hazard of UV-exposure is melanoma. Population studies have resulted in equivocal results, because it is difficult to differentiate sunbed UV-exposure from sunlight exposure. A recent prospective cohort study revealed a risk ratio for melanoma of 1.4 to 2.6, i.e. the risk increased by 40% – 160% depending on the age group. This is higher than the risk of radon on lung cancer, and radon is the most important radioactive radiation in terms of cancer causation. In Great Britain, it has been estimated that solarium use explains 6% of melanoma mortality. Unfortunately, the more dangerous UV-radiation seems to be of much less concern in the minds of the general population than radioactive radiation.
In animal experiments both UV-A and UV-B cause cancer, with UV-B being somewhat more effective. The contribution of each in solarium exposure is not known, because there is no valid animal model which can differentiate between them. There is no likely way to find out either, because humans cannot be exposed under controlled conditions to radiation.
Cancer has time to develop if exposure is at young age
A particular increase in the risk is seen, if sunbeds are used by young people. Presently about one out of every five sunbed users are between 20 and 24 years old, and a significant number are even younger. Because melanoma, just as any other cancer, progresses through a multi-step slow process, an early exposure provides ample time for cancer development. Moreover the health benefit is marginal, because vitamin D production by solarium light is less than can be obtained from sunlight.
Solariums must be regulated strictly. In many countries, there are legislative limits for dose rates. In addition, the users must be given accurate advice on how to regulate the dose in the solarium. A solarium-induced tan does not protect the skin as well as a suntan, because there is no skin thickening. Solarium is no place for children or even teenagers. Strict regulations or preferably a ban is needed to stop youngsters being tempted. As a senior risk professional I myself would be happy to go near the Chernobyl reactor, but I would absolutely refuse to visit a solarium.
Solariums are regulated in many countries so that very high risks are not likely. However, they are probably responsible for some melanomas every year in all countries. Before visiting a solarium it is advisable to stop for a while and think, if the tan is really worth the risk.
Notes and references
- Cohort study means that a certain group of people (a cohort) is followed over the years. Cohort is retrospective, or historical, or it is prospective or forward-directed. In the latter case, the accurate exposure is much easier to assess.
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