The definition of a 'healthy' amount of sun exposure may differ across Australia, a senior cancer researcher has warned.
Exposure to the sun is needed for the production of vitamin D, which is necessary for maintenance of bone health and may also be important for prevention of several cancers.
Australians are becoming confused as they attempt to strike a balance between keeping out of the sun to avoid skin cancer and getting enough sun to ensure healthy levels of vitamin D, Dr Rachel Neale said in an editorial in the latest issue of the Medical Journal of Australia.
Dr Neale, an epidemiologist working with the Queensland Institute of Medical Research in Brisbane, said the solution is not simple.
'It still may not be possible to provide a single message about 'healthy' sun exposure appropriate for the whole of Australia,' say Dr Neale and colleagues.
'It has been estimated that only 6-12 minutes of winter sun exposure three to four times a week may be sufficient to produce 'healthy' levels of vitamin D in Brisbane, compared with 51 minutes in Melbourne.'
In addition, Dr Neale said many factors contribute to a person's risk of skin cancer or ability to synthesise vitamin D, including age, skin type, body mass index, food choices, liver health, and environmental conditions.
Guidelines devised by skin, bone, and cancer specialists advise that sun protection is required if the UV index is three or above, that people living in southern Australia might need more sun exposure to achieve adequate vitamin D levels, that people at high risk of skin cancer need more rigorous sun protection, and that elderly people and those who cover themselves with clothing for cultural or religious reasons may need vitamin D supplementation.
However, Dr Neale said further research is needed into the science behind the recommendations, and that their complex nature may require further explanation for the general public.
'The challenge ... is to provide a public health message that ensures skin cancer risk is minimised while taking a precautionary approach to the possible harms of insufficient circulating levels of vitamin D,' Dr Neale said.
'In the interim, ... sun-safe practices should be encouraged and supplements used where necessary until we increase our basic understanding of the relationships between chronic disease, vitamin D and sunlight.'