LONDON, UK - The health benefits of sunlight may outweigh the risks of skin cancer in gloomier parts of the world, new research from Scotland suggests.
Scientists from the University of Edinburgh found exposure to higher levels of ultraviolet (UV) radiation is linked to a drop in deaths due to cancer and cardiovascular disease – including heart attacks and strokes.
The researchers believe adapting public health advice to reflect both risks and benefits may help improve life expectancy in low-sunlight countries, such as Scotland.
Their report said: "The benefits of UV exposure may outweigh the risks in low-sunlight countries.”
However, the experts continued to warn that people should still take protective measures to prevent sunburn and skin cancer.
Statisticians commenting on the report said it is important to avoid causation, and other factors may contribute.
Scientists used UK BioBank data to examine the UV exposure of 395,000 people from white European backgrounds – however "limitations” were raised by commentators, as participants were aged between 37 and 73 at the time of recruitment.
Living in locations with higher UV levels, for example Cornwall, was associated with a lower risk of death from cardiovascular disease and cancer – 19 per cent and 12 per cent respectively – than areas with lower UV levels, such as Edinburgh or Glasgow, according to the report.
The team asked participants if they used sunbeds and calculated average annual UV exposure based on region, and looked at the cause of death for participants who died.
Smoking, exercise, deprivation and gender were considered to reduce the chance these factors were responsible for any changes observed, and the report noted "evidence of a healthy volunteer selection bias”.
Sunbed use was linked to a 23 per cent lower risk of death from cardiovascular disease and a 14 per cent lower risk of fatal cancer in the report – however it was noted that sunbed users may potentially seek out greater sun exposure.
Those with a higher estimated UV exposure had a slightly increased risk of being diagnosed with melanoma – skin cancer – but their risk of dying from the condition was not raised, the report said.
The findings are of most relevance to low-sunlight countries, and experts said research into locations with higher UV exposure is needed to build a clearer picture of the potential benefits.
Professor Chris Dibben, of the university’s School of GeoSciences, said: "Our paper adds to a growing body of evidence suggesting that in lower-light environments, relatively higher exposure to UV is good for your health.
"Though there may be an increased risk of skin cancer incidence with higher UV exposure, this risk appears to be outweighed by a larger reduction in the risk of death from cancer and cardiovascular-related disease.”
Professor Richard Weller, from the university’s Centre for Inflammation Research, said: "Dermatologists traditionally only considered possible harm to the skin caused by sunlight, much of which dates from the experience of white-skinned individuals in sunny countries such as Australia. When the UV index is very high, protecting skin is important.
"Research shows that in the UK, the balance of benefit and risk is probably very different from that in sunnier countries.”
The study, Higher Ultraviolet Light Exposure Is Associated With Lower Mortality: An Analysis Of Data From The UK Biobank Cohort Study, was published in Health & Place, funded by Health Data Research UK.
Rachel Richardson, of the evidence synthesis network Cochrane, said: "Participants are not representative of the population – the UK BioBank only includes people between the ages of 37 and 73 at recruitment. These findings may not apply to older and younger age groups.
"A second limitation is that some results are based on small numbers of participants, for example mortality from melanoma. This means there is not enough information to draw conclusions about whether there was an association between UV exposure.”
Professor Kevin McConway, an emeritus professor of applied statistics at the Open University, said: "On average, deaths occurred later in people who lived in sunnier parts of the UK, or used a sunbed at least once a year.
"The snag is that people who live in different parts of the country differ in many other ways than the amount of UV radiation, and sunbeds. The correlation between UV exposure and death rates could be caused by other factors.
"The researchers rightly point out there may be some relevant confounding factors they did not adjust for – and it’s not possible to adjust for factors on which there is no data.
"Some doubt has to remain about the extent to which the different UV exposures explain the differences in death rates, in terms of cause and effect.” - DPA