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| Prof. Werner Sinclair |
“Some evidence exists which implies that sunscreens could indeed be responsible for the dramatic rise in the incidence of melanoma over the past three decades, the period during which the use of sunscreens became very popular,” says Prof. Werner Sinclair, Head of the Department of Dermatology at the University of the Free State. His inaugural lecture was on the topic Sunscreens – Curse or Blessing?
Prof. Sinclair says the use of sunscreen preparations is widely advocated as a measure to prevent acute sunburn, chronic sun damage and resultant premature skin aging as well as skin malignancies, including malignant melanoma. There is inconclusive evidence to prove that these preparations do indeed achieve all of these claims. The question is whether these preparations are doing more harm than good?
He says the incidence of skin cancer is rising dramatically and these tumours are induced mostly by the ultra-violet rays.
Of the UV light that reaches the earth 90-95% belongs to the UVA fraction. UVC is normally filtered out by the ozone layer. UVB leads to sunburn while UVA leads to pigmentation (tanning). Because frequent sunburn was often associated with skin cancer, UVB was assumed, naively, to be the culprit, he says.
Exposure to sunlight induces a sense of well-being, increases the libido, reduces appetite and induces the synthesis of large amounts of vitamin D, an essential nutritional factor. The use of sunscreen creams reduces vitamin D levels and low levels of vitamin D have been associated with breast and colon cancer. Prof. Sinclair says the 17% increase in breast cancer from 1981 to 1991 parallels the vigorous use of sunscreens over the same period.
Among the risk factors for the development of tumours are a family history, tendency to freckle, more than three episodes of severe sunburn during childhood, and the use of artificial UV light tanning booths. He says it remains a question whether to tan or not. It was earlier believed that the main carcinogenic rays were UVB and that UVA merely induced a tan. The increase in UVA exposure could have severe consequences.
Prof. Sinclair says the UV light used in artificial tanning booths consists mainly of pure UVA which are highly dangerous rays. It has been estimated that six per cent of all melanoma deaths in the UK can be directly attributed to the use of artificial tanning lights. The use of an artificial tanning booth will double the melanoma risk of a person. “UVA is solely responsible for solar skin aging and it is ironical that tanning addicts, who want to look beautiful, are inflicting accelerated ageing in the process,” he says.
On the use of sunscreens he says it can prevent painful sunburn, but UVA-induced damage continues unnoticed. UVB blockers decrease vitamin D synthesis, which is a particular problem in the elderly. It also prevents the sunburn warning and therefore increases the UVA dosage that an individual receives. It creates a false sense of security which is the biggest problem associated with sunscreens.
Evidence obtained from the state of Queensland in Australia, where the heaviest and longest use of sunscreens occurred, boasted the highest incidence of melanoma in the world. A huge study in Norway has shown a 350% increase in melanoma for men and 440% for women. This paralleled the increase in the use of UVB blocking sunscreens while there was no change in the ozone layer. It did however, occur during that time when tanning became fashionable in Norway and there was an increase especially in artificial tanning.
Prof. Sinclair says: “We believe that sunscreen use does not directly lead to melanoma, but UVA exposure does. The Melanoma Epidemic is a reality. Sunscreen preparations are not the magical answer in the fight against melanoma and the irresponsible use of these preparations can worsen the problem.”
Media Release
Issued by: Mangaliso Radebe
Assistant Director: Media Liaison
Tel: 051 401 2828
Cell: 078 460 3320
E-mail: radebemt.stg@ufs.ac.za
7 December 2009