The sunscreen industry would have you believe that all sun exposure is potentially dangerous.
Simon Best argues that other factors like a Western diet may be more responsible for skin cancer.
If there's one thing that everyone looks forward to, it's the summer, and holidays basking in the sun on a beach. But if the ongoing propaganda from official and commercial sources is to be believed, exposing ourselves to the sun is the last thing we should be doing.
Throughout history, the sun has generally been considered a powerful source of beneficial energy, both in myth and reality. In medicine, the practice of heliotherapy exposing patients to controlled amounts of sunlight to cure or alleviate illness was an accepted practice in many countries from the late 19th to the mid 20th century.
Dr Auguste Rollier, probably the most famous heliotherapist of his day, had 36 clinics with over 1000 beds in Leysin, Switzerland. He used sunlight to treat illnesses such as tuberculosis, rickets, smallpox, lupus vulgaris (tuberculosis of the skin) and wounds. Rollier found that sunbathing early in the morning and eating a nutritious diet produced the best results.
However, with the ascendency of the pharmaceutical industry, heliotherapy fell into disuse.
Since the 1960s, the public has been increasingly bombarded with warnings about sunbathing and the risks of skin cancer, with little information on the benefits of sunlight. But reasonable assessments comparing the risks and benefits of exposure to the sun show that the positive effects of sun exposure vastly outweigh its potential hazards.
The incidence of skin cancers has increased over the past few decades (see box on p 2). It is also known that overexposure to solar radiation can cause premature ageing of the skin. However, the vast majority of non melanoma skin cancers are curable and associated with a very small number of deaths (see box on p 2), given a total population of perhaps 40 million sunbathers.
To put the risks from solar radiation into proper perspective, alternative causes of skin cancer and contributory risk factors need to be considered. But first, the actual health risks of UV, the main alleged threat from sunshine, need to be assessed.
UV light can be divided into three main types, according to wavelength (see box on p 1). Of the sunlight reaching the earth, a mere 3 per cent is UV. Both UVA and B promote tanning and sunburn, but UVB is critical for photosynthesis of vitamin D, which is essential for healthy bone development and other processes.
Another argument against the idea that simple exposure to UV radiation causes cancer is the finding that melanomas seldom occur in outdoor workers. A study of US Navy personnel from 1974 to 1984 found a higher risk in sailors with indoor jobs than in those working outdoors (Arch Environ Health, 1990; 45: 261-7). Those working both indoors and outside had the most protection, with a melanoma incidence 24 per cent below the US national average.
Such findings support those of other studies indicating that, while severe sunburn may trigger melanoma, moderate sun exposure may prevent it (Lancet, 1982; ii: 290-3). Indeed, there is some evidence that regular, moderate sun exposure has other benefits as well.
In London based Dr Damien Downing's book Day Light Robbery (Arrow Books, 1981), he states that melanin protects against sun induced free radical damage. He also says: "It seems that even without UV light, skin lipids will take up some oxygen from the air and use it to kill bacteria. However, this effect is much more intense under UV."