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Sun Exposure and Health

Posted on: Thursday, 18 August 2005, 03:00 CDT

Summary

This article discusses the current confusion regarding sun exposure. Having been told for many years to avoid the sun in an effort to prevent skin cancer, we are now being told that we may actually need to increase our exposure to sunlight to improve our health. Both sides of the debate are discussed and the information available is reviewed.

Keywords

Health promotion; Skin cancer

These key words are based on the subject headings from the British Nursing Index. This article has been subject to double- blind review. For related articles and author guidelines visit our online archive at www.nursing-standard.co.uk and search using the key words

THE UK POPULATION is being advised to practise sun avoidance, both by public bodies (Health and Safety Executive (HSE) 2001, National Radiological Protection Board (NRPB) 2002) and cancer charities (Cancer Research UK 2004a, Wessex Cancer Trust 2004). Sun exposure is the biggest factor in the incidence of skin cancer (Armstrong and Kricker 2001), and sun avoidance advice is aimed at improving the nation's health. For example, the tenets of the government-funded 'SunSmart' campaign (Box 1 ) are designed to reduce a person's exposure to sunlight and in particular to prevent episodes of sunburn. However, in recent months, there has been considerable coverage in the national press, suggesting that people should increase their exposure to sunlight (Box 2). The subject has featured in articles such as 'Avoiding the sun can be bad for your health' in The Daily Telegraph (Hall 2004), and 'Official: get more sun' in The Guardian (Jha 2004). It is suggested that increased sun exposure can guard against diseases as diverse as hypertension, diabetes, multiple sclerosis and cancer. This article examines this apparent discrepancy and considers the implications for healthcare professionals, who might give guidance to patients on the advantages and disadvantages of sun exposure.

Background

Over the past 200 years, fashions have swung between the poles of sun avoidance and sun worship. In the late 19th century, genteel ladies would cover up with brimmed hats, veils and parasols to avoid an unfashionably tanned complexion (Albert and Ostheimer 2002). Their great granddaughters might well have sunbathed in the first bikinis, or even topless. In more recent times, a tanned appearance has remained fashionable (Arthey and Clarke 1995), despite efforts such as the 'Are you dying to get a suntan?' campaign of the late 1980s.

In the world of medicine, there have also been changes in how sunlight has been regarded. In the late 19th and early 20th centuries, suntanning was often advocated by the medical profession for its perceived health-affirming properties (Albert and Ostheimer 2003a). At the time, phototherapy was used, usually in the form of ultraviolet lamps, to successfully treat conditions as diverse as cutaneous tuberculosis and psoriasis (Albert and Ostheimer 2002). Over time, however, it was realised that sunlight plays a role in skin ageing, skin cancer, cataracts of the eye and suppression of the immune system (World Health Organization (WHO) 2004). This in turn has led to attempts to change people's sun exposure behaviour through health promotion.

BOX 1

The SunSmart campaign: how to protect your skin

BOX 2

Recent newspaper headlines

The impact of skin cancer

Skin cancer is one of the most common cancers in the UK, with over 69,000 new cases reported every year (Cancer Research UK 2004c). The most frequent forms of skin cancer are: basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Although these two cancers are distinct diseases, they are often referred to collectively as non-melanoma skin cancer. These cancers are rarely fatal, but they are a significant drain on scarce healthcare resources and result in considerable patient distress and suffering, particularly from surgical procedures.

The other major form of skin cancer is the far more dangerous malignant melanoma (MM), which in 2002 resulted in over 1,600 deaths (Cancer Research UK 2004c). MM makes up a smaller proportion of skin cancers, but is far more dangerous because of the greater likelihood of it metastasising to other parts of the body. The incidence of MM in the UK has doubled in the last 20 years (Cancer Research UK 2004c). With the UK's aging population, and without a change in current lifestyle patterns, it is reasonable to expect an ever- increasing burden from skin cancer morbidity and mortality.

The nature of sunlight

Sunlight underpins virtually all life on earth and is such a ubiquitous resource we often give it little thought. However, in addition to the light that enables us to see, sunlight also contains ultraviolet (UV) and infrared (IR) rays. These two components are invisible to the human eye and are therefore, strictly speaking, not actually light. They are more properly termed 'radiation' and reside either side of the visible spectrum (hence their names). IR radiation gives sunlight its heat, while UV radiation (UVR) can damage the skin, eyes and immune system (WHO 2004). UVR makes up about 5 per cent of terrestrial sunlight and is commonly divided by wavelength into UVA, UVB and UVC (UVC having the shortest wavelength) (Diffey 2002). Before sunlight reaches the earth's surface, the atmosphere typically absorbs the UVC and much of the UVB. This means that most of the UVR that reaches us is UVA, with a small amount of UVB (WHO 2004).

The role of sunlight in skin cancer

UVR in sunlight is widely held to be the most significant causal factor in BCC, SCC and MM (Armstrong and Kricker 2001). As early as the 1930s, experiments on rodents demonstrated that both sunlight and UV lamps could induce skin cancers (Albert and Ostheimer2003b). Although a tan may signify a relaxing holiday socially, its true function is defence - it demonstrates the creation of extra pigment to block UVR (Hockberger 2002).

The role of UVR and skin cancer is not as straightforward as it might appear. The greater a person's cumulative exposure to UVR the greater his or her risk of developing SCC, while with BCC and MM intense intermittent exposure is believed to be a greater indicator of risk (Elwood and Jopson 1997, Armstrong and Kricker 2001). It has even been suggested that a year-round tan from regular, occupational exposure to the sun could be protective against developing MM (Elwood and Jopson 1997).

The influence of skin type

The European Code Against Cancer recognises that individuals vary in their sensitivity to the sun (Europe Against Cancer 2003). This is due to natural variations in skin pigmentation - those with the palest skin are at greatest risk and need to take the greatest precautions. However, the strongest risk factor for melanoma is the presence of numerous abnormal moles, that is moles of variable colour and shape, larger than 5mm in diameter (Europe Against Cancer 2003). Atypical mole syndrome (AMS) is present in approximately 2 per cent of the north European population (Europe Against Cancer 2003).

In general, the darker a person's natural skin colour the more protected he or she is against sun damage, but anyone can get sunburnt- it is just a question of how much sun exposure is required (Marks 1995).

The origin of the SunSmart campaign

The SunSmart campaign is jointly commissioned by the separate UK Health Departments, and is run by the national cancer charity Cancer Research UK. It was launched in 2003 to raise awareness about skin cancer and sun protection among members of the public and healthcare professionals. It is possible that being run by a highly regarded charity gives the SunSmart campaign greater weight with the public, particularly in comparison with direct Department of Health advice. This was demonstrated by the sceptical public reaction to government statements during the controversy over the MMR vaccine. Judging by its name, the SunSmart campaign takes inspiration from an Australian education programme run by the Cancer Council of Victoria, which started almost 25 years ago (SunSmart-Victoria 2004).

The SunSmart campaign is based on the belief that reducing a person's cumulative sun exposure, and any pattern of intense intermittent exposure, will reduce his or her likelihood of developing skin cancer. If its advice is followed, not only will an individual's total sun exposure decrease, his or her risk of sunburn will also be curbed. Emphasis is on avoiding 'peak' hours (11 am to 3 pm), when UVR exposure is greatest - when the sun is at its highest in the sky, sunlight has less atmosphere to penetrate so less UVR is blocked. Also the higher the sun is in the sky, the smaller the area over which its sunlight, and hence UVR, is distributed (Diffey 2002).

Criticisms of the SunSmart campaign

The SunSmart campaign is a professional undertaking, based on authoritative sources. The website is clear and accessible. However, the campaign has received criticisms on a number of levels. It has been suggested that the advice it gives is more suited to the Australian experience than the northern European one because of differences in climate and levels of solar radiation (Gillie 2004). It has also been pointed out that the degree to which a person is susceptible to sunshine varies and that only people who are particularly at risk may need to follow such stringent advice (Gillie 2004). SunSmart advice is aimed at the UK population at large and does not seem toallow for the ethnic diversity of the population. The SunSmart tenets (Box 1) are arguably too restrictive for a person with naturally highly-pigmented skin, for example, someone of African-Caribbean descent. Little reference to such ethnic subtleties was found on the SunSmart website. In recent months, new information has been added to the website, which links sun protection advice to skin type, and to the Met Office forecasts of UV intensity. However, they do not, as yet, seem to be a core part of the campaign (Cancer Research UK 2005).

Sun exposure

So if the case for limiting UVR exposure is overwhelming, why is the press coverage advocating more, rather than less, sun exposure? Partly this is due to the idea that sunlight can induce a subjective sense of wellbeing (Ness et al 1999). For example, seasonal affective disorder (SAD) is well recognised as a negative mood disturbance associated with lower levels of daylight in winter (Birtwistle and Martin 1999). It is often successfully treated with phototherapy using so-called 'light boxes' (Birtwistle and Martin 1999).

More particularly, recent press coverage seems to have been stimulated by an increasing scientific interest in vitamin D, and the role it plays within the human body. Since vitamin D is both absorbed from dietary sources and synthesised in the skin in response to UVR exposure, the issue of sun protection has come under scrutiny. In fact, sunlight is probably the major source of vitamin D for most people (Holick 2001).

It has long been recognised that vitamin D deficiency can lead to rickets but it is now being suggested that it can predispose to a range of other diseases as disparate as coronary heart disease (Ness et al 1999) and cancer of the prostate (John et al 2004). It has even been suggested that if vitamin D does have a protective effect against malignancy, then reducing sun exposure to prevent skin cancer will increase the total number of cancers (Selby and Mawer 1999). More recently, an article in The Times entitled 'Secret to summer loving: vitamin D' suggested that sunlight might even improve male fertility (Henderson 2004). The article explained that the effect of extra vitamin D would be smaller than other factors, such as smoking and alcohol - a rather different emphasis from the headline.

Differing opinions

The debate over sun exposure, vitamin D and health has been going on within medical circles for some time. In the UK, this has mainly been discussed in The Lancet and the British Medical journal. To a certain extent, opinions appear to be informed by speciality, with dermatologists understandably concerned with recent, dramatic increases in skin cancer rates. Other professionals, such as nutritionists, have tended to be more interested in the possible benefits of sun exposure to other parts of the body.

One prominent advocate of greater sun exposure to boost vitamin D levels is the American Professor Michael Holick. He has suggested that sun protection advice needs to be moderated because of the possible importance of vitamin D in cellular health (Holick 2001). Holick claims to have been vilified and driven to resign his professorship of dermatology because of his views (O'Neill 2004). This is possibly an indication of how heated this debate has become, particularly in the US.

Sunscreens

It might well be thought that sunscreens provide a solution to the problem of balancing cutaneous production of vitamin D while still avoiding UVR damage to the skin. However, sunscreens are a controversial area. The effectiveness of sunscreens in preventing skin cancer has been questioned, partly because they are often applied incorrectly and could encourage people to spend longer in the sun (Fry and Verne 2003). Questions have also been raised over the effectiveness of many sunscreens in absorbing damaging UVA radiation, not just the UVB radiation that causes sunburn (Garland 2003). The most important point, however, is that the UVB exposure that sunscreens reduce is the stimulus for vitamin D production (Diffey 1998).

BOX 3

Summary of key points

The perspective of the press

The general public could be excused for being confused about the messages they are receiving about sunlight. The press could be accused of misrepresenting the wider role for vitamin D. The press has tended to emphasise the need for greater sun exposure to create vitamin D rather than increasing dietary intake. Fatty fish, cod liver oil and egg yolk are all good sources of vitamin D, and in the UK breakfast cereals and margarine are often fortified with it (Institute of Food Research (IFR) 2004).

Possibly the press has emphasised sun exposure because it makes a better story; it certainly makes better headlines. Following a recent press briefing from the IFR on the importance of vitamin D, five national papers referred to increasing exposure to the sun in their article titles. In contrast, the IFR summary on the internet only mentions the effect of a dominance of indoor activities on the vitamin D levels of young adults (IFR 2004).

Vitamin D levels

The fundamental question would appear to be: how much sunshine is needed - taking into account dietary sources - to meet the body's requirements for vitamin D? Supporters of the SunSmart campaign would contend that casual exposure of uncovered skin, for example, on the hands and face, is sufficient for adequate production of vitamin D. Others such as Gillie (2004) contend that far more is required.

Nutritionists have suggested that current recommended levels for vitamin D are too low (IFR 2004), further complicating the debate. In the UK the Committee on Medical Aspects of Food and Nutrition Policy (COMA), does not have a recommended dietary intake for adults leading a normal lifestyle. This is primarily because it is so difficult to calculate how much vitamin D the body produces in response to sunlight. With the role of vitamin D only partially understood, it is also difficult to calculate the required target levels. It is known that excessive vitamin D intake can be harmful and may lead to hypercalcaemia and hypercalciuria (Expert Group on Vitamins and Minerals 2003).

Conclusion

The crux of the matter is determining whether sun protection advice results in vitamin D deficiency and, if so, does that have ill effects on the individuals concerned ? If a negative effect were established, the question would then be: can that deficiency be addressed in other ways? And, if not, does that deficiency outweigh the putative drop in skin cancer rates? In this context the only way to determine this is to do further research.

To summarise (Box 3), the issues concerning sun exposure and vitamin D are complex, but the rationale of the SunSmart campaign has yet to be negated by the current interest in the wider role of vitamin D. Skin damage and skin cancer are proven risks of excessive sun exposure and need to be addressed. If nurses are looking for health promotion material on sun exposure, the SunSmart campaign is a sensible and logical resource to use. The UK population has an increasingly varied ethnic composition and sun protection advice needs to encompass the consequent variation in skin pigmentation. A 'one size fits all' approach is not sufficient

Affleck P (2005) Sun exposure and health. Nursing Standard. 19, 47, 50-54. Date of acceptance: February 24 2005.

References

Albert MR, Ostheimer KG (2002) The evolution of current medical and popular attitudes toward ultraviolet light exposure: part 1. Journal of the American Academy of Dermatology. 47, 6, 930-937

Albert MR, Ostheimer KG (2003a) The evolution of current medical and popular attitudes toward ultraviolet light exposure: part 2. Journal of the American Academy of Dermatology. 48, 6, 909-918.

Albert MR, Ostheimer KG (2003b) The evolution of current medical and popular attitudes toward ultraviolet light exposure: part 3. Journal of the American Academy of Dermatology. 49, 6, 1096-1106.

Armstrong B, Kricker A (2001) The epidemiology of UV induced skin cancer. Journal of Photochemistry and Photobiology. 63, 1-3, 8-18.

Arthey S, Clarke VA (1995) Suntanning and sun protection: a review of the psychological literature. Social Science and Medicine. 40, 2, 265-274.

Birtwistle J, Martin N (1999) Seasonal affective disorder: its recognition and treatment. British Journal of Nursing. 8, 15, 1004- 1009.

Cancer Research UK (2004a) SunSmart. www.cancerresearch uk.org/ sunsmart (Last accessed: July 14 2005.)

Cancer Research UK (2004b) Stay Safe. www.cancerresearchuk.org/ sunsmart/staysafe/ (Last accessed: July 14 2005.)

Cancer Research UK (2004c) Briefsheets: Skin Cancer. March 2004. www.cancerresearchuk/org/ aboutus/publications (Last accessed: July 14 2005.)

Cancer Research UK (2005) Three Quarters of Britons Confused by Sun Warnings. www.cancerresearchuk. org/news/pressreleases/ britons_sun_ warnings_23may05 (Last accessed: July 18 2005.)

Diffey BL (1998) Sun protection: have we gone too far? (Letter) British Journal of Dermatology. 138, 3, 562-563.

Diffey BL (2002) What is light? Photodermatology, Photoimmunology and Photomedicine. 18, 2, 68-74.

Elwood JM, Jopson J (1997) Melanoma and sun exposure: an overview of published studies. International Journal of Cancer. 73, 2, 198- 203.

Europe Against Cancer (2003) European Code Against Cancer and Scientific Justification: Third Version (2003). www.cancercode.org/ code_06. htm (Last accessed: July 14 2005.)

Expert Group on Vitamins and Minerals (2003) Safe Upper Levels for Vitamins and Minerals. Food Standards Agency, London.

Fry A, Verne J (2003) (Editorial) Preventing skin cancer. British Medical Journal. 326, 7381, 114-115.

Garland CF (2003) More on preventing skin cancer: sun avoidance will increase incidence of cancers overall. (Letter) British Medical Journal. 327, 7425, 1228.

Gillie O (2004) Sunlight Robbery: Health Benefits of Sunlight are Denied by Current Public Health Policy in the UK. Health Res\earch Forum, London.

Hall C (2004) Avoiding the sun can be bad for your health. The Daily Telegraph. September 17

Health and Safety Executive (2001) Sun Protection Advice for Employers of Outdoors Workers. HSE, London.

Henderson M (2004) Secret to summer loving: vitamin D. The Times. October 19.

Hockberger P (2002) A history of ultraviolet photobiology for humans, animals and microorganisms. Photochemistry and Photobiology. 76, 6, 561-579.

Holick MF (2001) Sunlight dilemma: risk of skin cancer or bone disease and muscle weakness. The Lancet. 357, 9249, 4-6.

Institute of Food Research (2004) Vitamin D Briefing: A Summary. www.ifr.ac.uk/media/ newsreleases/vitd.html (Last accessed: July 14 2005.)

Jha A (2004) Official: get more sun. The Guardian. September 17

John EG, Dreon DM, Koo J, Schwartz GM (2004) Residential sunlight exposure is associated with a deceased risk of prostate cancer Journal of Steroid Biochemistry and Molecular Biology. 89-90, 1-5, 549-552.

Marks R (1995) Sun and the Skin. Second edition. Martin Dunitz, London.

Ness AR, Frankel SJ, Gunnell DJ, Smith GD (1999) Are we really dying for a tan? British Medical Journal. 319, 7202, 114-116.

National Radiological Protection Board (2002) Advice on Protection Against Ultraviolet Radiation. National Radiological Protection Board, Didcot, Oxfordshire.

O'Neill B (2004) They Have Vilified the Sun - and Me. www.spikedonline.com/Articles/0000000CA61 6.htm (Last accessed: July 14 2005.)

Selby P, Mawer E (1999) Sunlight and health: exposure to sunlight may reduce cancer risk. (Letter) British Medical Journal. 319, 7216, 1067-1068.

SunSmart-Victoria (2004) SunSmart overview. SunSmart Victoria. www.sunsmart.com.au (Last accessed: July 14 2005.)

Wessex Cancer Trust (2004) Sun Protection. www.wessexcancer.org/ supportysun_protection.htm (Last accessed: July 14 2005.)

World Health Organization (2004) Ultraviolet Radiation and the INTERSUN Programme. www.who.int/uv/en/ (Last accessed: July 14 2005.)

Author

Paul Affleck is research nurse, Division of Genetic Epidemiology, Cancer Research UK Clinical Centre, St James' University Hospital, Leeds. Email: paul.affleck@cancer.org.uk

Copyright RCN Publishing Company Ltd. Aug 3-Aug 9, 2005

Source: Nursing Standard

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