Overexposure to UV radiation is the main cause of skin cancer

There is sufficient evidence to show that overexposure to ultraviolet (UV) radiation is the main preventable cause of skin cancers – both malignant melanoma and non- melanoma skin cancers (NMSC)1  2  3. The sun is the principal source of natural UV radiation. Sunbeds produce artificial UV radiation.

A study published in 2011 estimated that 86% of melanomas in the UK (around 11,100 cases) every year are linked to too much exposure to sunlight and sunbed use4.

Among NMSCs, an estimated 50-70% of squamous cell carcinomas (SCCs) and 50-90% of basal cell carcinomas (BCCs) in fair-skinned people are caused by UV radiation5.

The risk of melanoma is most strongly linked to intermittent sun exposure6. Non-melanoma skin cancers (BCCs and SCCs) are both linked to chronic sun exposure7 8. The risk of BCCs is also linked to intermittent sun exposure9 10.

Some people are at higher risk of skin cancer

Some people are more likely than others to develop skin cancer. These people tend to have one or more of the following:

  • fair skin that burns easily11 12;
  • lots of moles13 14 or freckles15;
  • a history of sunburn6 16  and/or having had significant sun exposure throughout your life7 8;
  • red or fair hair15;
  • light-coloured eyes15;
  • a personal17 18 or family history19 20 of skin cancer.

People with naturally dark brown/black skin have a lower risk of skin cancer 21 22 23 But people with darker skin can still burn and develop skin cancers, especially on non-pigmented parts of the body like the soles of the feet 24.

The UV Index and strength of UK sunlight

The World Health Organisation (WHO) developed an international UV index to reflect the strength of the sun’s rays or level of UV radiation at the earth’s surface. The level of UV radiation gives an indication of the risk of burning or adverse health effects. The greater the UV index value, the greater the potential for damage and the less time it takes for this damage to occur25 26. The UV index can be used as an indication for the level of protection needed against UV radiation. It is widely accepted that protection is needed only when the UV index is above 327.

The strength of UV radiation reaching the earth’s surface is affected by several factors:

  • Time of day, being strongest at solar noon when the sun is highest in the sky26
  • Time of year, being strongest in the summer months28
  • Latitude, being strongest in locations nearer the equator1
  • Altitude – spending time at high altitude increases UV exposure by about 15% for every 1000 metres1  29 
  • Cloud cover – even on overcast skies, 30-40% of UV radiation will still penetrate through cloud cover30 31 32. For example, if half the sky is covered in clouds, 80% of UV radiation still shines through30 .
  • Reflection – snow can reflect up to 85% of the UV radiation that hits it, increasing a person’s exposure33. About 15% of sunburning rays are reflected back from sand, 10% from concrete and 5-10% from water (depending on choppiness)34.

 

Skin type and burn risk

A combination of hair and eye colour, as well as how skin reacts (how often or easily it burns) in the sun can be used to estimate a person’s risk of skin cancer. Experts have identified six different skin types using this skin phototype classification method35 36.

Skin phototype Typical Features Tanning Ability
Type I Tends to have freckles, red or fair hair, and blue or green eyes. Often burns, rarely tans.
Type II Tends to have light hair, and blue or brown eyes. Usually burns, sometimes tans.
Type III Tends to have brown hair and eyes. Sometimes burns, usually tans.
Type IV Tends to have dark brown eyes and hair. Rarely burns, often tans.
Type V Naturally black-brown skin. Often has dark brown eyes and hair.  
Type VI Naturally black-brown skin. Usually has black-brown eyes and hair.  



The Health Protection Agency developed a tool for estimating a person’s risk of burning and the level of protection they need based on their skin type and the UV index37.

The shadow rule

UV exposure varies depending on the time of day but is highest between 10am and 3pm, international organisations such as IARC (International Agency for Research on Cancer) and WHO (World Health Organisation) recommend limiting sun exposure during these times 38 47. A simple guide has been developed to help indicate when UV exposure might be high, called Holloway’s rule, which states that when your shadow is shorter than you are tall, the sun is more likely to burn you39.

How UV radiation causes skin cancer

UV radiation from the sun damages DNA, which can lead to the development of cancer40.There are two main types of UV rays that damage skin:

  • UVB is responsible for the majority of sunburns and it can cause skin cancer 41 47.
  • UVA penetrates deeper into the skin. It ages the skin, but contributes much less towards sunburn41 42  43.

Both UVA and UVB can damage DNA in the skin, which can lead to skin cancer3  44. DNA damage caused by UV radiation leads to a number of changes in the body. Blood vessels dilate, producing a red colour and increasing the surface temperature (because hot blood is rushing to the surface). The widened blood vessels also allow immune cells and inflammatory chemicals to rush to the site of the damage, which cause the swelling and pain that accompanies sunburn. If skin cells are too heavily damaged, they are destroyed and peel away. Your body has ways of repairing most of the damage. But it is not perfect, and some damaged DNA can be left behind47.

A third type of UV ray, UVC, is the most dangerous of all, but it is completely blocked out by the ozone layer and doesn’t reach the earth's surface47.

Getting sunburn increases the risk of skin cancer

Sunburn at any age doubles the risk of melanoma6 45. Getting a painful sunburn just once every two years can triple the risk of melanoma 46.

Sunburn during childhood can increase the risk of skin cancer later on in life. But the risk of malignant melanoma is increased regardless of whether sunburn occurred in childhood or adulthood6 46

Sunburn is a sign of DNA damage by too much UV radiation. It is the skin’s reaction to UV-induced damage47 48 49

A survey by Cancer Research UK and Nivea Sun showed that 37 per cent of people admitted the last time they were sunburnt was in the UK50.

Sun protection

It is widely agreed that a combination of measures including using shade, clothing and sunscreen, offers the best protection against over-exposure to UV radiation from the sun47 51. And research suggests that shade and clothing may offer better protection from UV rays than sunscreen52  53  54

Shade

Shade structures can provide protection from the sun. Staying under shade, such as a tree or umbrella, can reduce your overall exposure to UV, but not completely.  Many shade structures are more likely to filter than to block UV radiation. Only very broad and thick shade such as thickly wooded areas and widely overhanging structures provide enough protection55.

Clothes, hats, sunglasses

Covering up with clothes, hat and sunglasses is a commonly recommended and effective way of protecting yourself from UV rays56.

Clothes tend to provide more protection if they57:

  • Are dark-coloured
  • Are made of synthetic fabrics
  • Are dry – when some fabrics get wet, their protection can be halved
  • Have a close weave or are knitted.

Wide-brimmed hats provide the most UV protection for the whole face and head. Caps protect the nose and forehead but provide poor protection for other parts of the face58  59.

Sunglasses can protect your eyes from too much UV exposure. Poorly-fitting sunglasses offer poor protection as sunlight can reflect off the back face of the lens back into the eye. Wraparounds are recommended60 .

Sunglasses should state that they block out 100% of UVA and UVB rays. Alternatively, look for the ‘CE Mark’ and British Standard, or a UV 400 label. Remember that the UV-protective chemical on sunglasses is invisible, so the colour of the lens is not an indication of protection - in fact, the darkest sunglasses may cause pupil dilation and actually let more light in61 .

Sunscreen

Many studies have shown that sunscreen can reflect or absorb harmful UV rays47. However, the exact impact of sunscreen use on skin cancer risk remains unclear 62 63 64.

Using sunscreen for ‘non-intentional’ sun exposure, such as walking, gardening, sport or other daily activities, could reduce the risk of sunburn 65 66. However, using sunscreen for ‘intentional’ sun exposure (e.g. sunbathing) has been linked with people spending longer in the sun overall and being no less likely, perhaps even more likely to get sunburnt66. This was particularly seen when people used higher SPF sunscreens67.

Because of this, we recommend that sunscreen should be used together with clothing and shade to protect the skin from sun damage, and should never be used to spend longer in the sun.

The SPF or ‘factor’ of a sunscreen is a measure of the amount of sun protection it provides. Experts have found that SPF 15 sunscreen provides sufficient protection when used appropriately47 68. In the UK, a minimum of SPF 15 is recommended by NICE (National Institute for Health and Care Excellence)69.

SPF measurements are based on the assumption that people apply 2mg/cm2 of sunscreen on their body47. But using this quantity of sunscreen may be unachievable in practice70. Research has shown that people don’t apply enough71. One study found that people only apply 0.5-1mg/cm2 72.

Sunscreen only works if you use enough. It should be applied evenly, thickly and regularly to be effective73 74 75 76. As a guide, for an average person, you should use77:

  • around two teaspoonfuls of sunscreen if you're just covering your head, arms and neck.
  • around two tablespoonfuls if you're covering your entire body, while wearing a swimming costume.

As SPF increases, sunscreens provide less and less extra protection. An SPF15 sunscreen filters out 93% of UVB radiation, while an SPF30 sunscreen filters out 96%78.

Sunscreens that provide UVA protection are recommended51 79. The star rating system measures the balance between UVA and UVB protection and awards products a rating of 0-5 stars. It is not an absolute measure, but depends on the SPF rating of the sunscreen it is applied to.

Protecting children

Over-exposure to the sun during childhood can affect the risk of melanoma later in life 80, 81.

When parents use sun protection such as hats, shade, sunscreen and clothing, their children are more likely to use these sun protection methods too 82. It's important to establish good sun protection habits early on in life 83.

Parents are advised to keep babies under 6 months out of direct sunlight 84, 85.

Sunbeds and skin cancer risk

According to IARC there is sufficient evidence that sunbed use causes malignant melanoma, and limited evidence that sunbed use causes SCC 3.

According to a recent meta-analysis sunbed use at any age increases the risk of SCC by 67%, and increases BCC risk by 29% 86.

A comprehensive review published in 2012 of studies on sunbeds and cancer concluded that using a sunbed for the first time before the age of 35 increases the risk of malignant melanoma by 59%, and use at any age increases malignant melanoma risk by 20-25% 87.

A large study of Norwegian and Swedish women found that using sunbeds once a month or more increases the risk of melanoma by 55% in all age groups from 10-39 88.

Sunbeds are marketed as a 'controlled' way of getting a 'safer' tan 89. But actually, sunbeds are no safer than exposure to the sun itself 90. It is a common misconception that sunbeds emit only UVA radiation, and not UVB, the type which causes more sunburns. But all sunbeds emit some measure of UVB, and even this tiny proportion is enough to cause substantial damage to our skin 91.

UVA can also damage the skin and the levels of UVA from sunbeds can be over 10 times higher than that of the midday sun 92. A recent study found that the average skin cancer risk from sunbeds can be more than double that of spending the same length of time in the Mediterranean midday summer sun 93.

Studies have shown that up to half of all sunbed users suffer from sunburn 94.

Sunbeds and photoageing

In addition to carcinogenic effects, sunbeds can promote photoageing - UV-induced premature ageing of the skin - by destroying collagen and other large molecules. The consequences of UVA-induced damage in the skin include the formation of wrinkles, sagging, leathery appearance, fragility and impaired healing ability 95.

A French study found that women who frequently used sunbeds over the course of 5 years developed saggier skin with a loss of elasticity that resembled premature ageing 96. Another study of 59 people who used sunbeds over 3 months found that their skin cells showed a 2.4 fold increase in the levels of a common fault in mitochondrial DNA that is firmly associated with photoageing 97.

Tanning

Far from being a sign of health, a tan is a reaction to DNA damage in the skin. It is a sign that your body is trying to repair damage that has already happened 98, 99. And pre-holiday tans or sunbed tans offer very little protection against the sun. Some studies have found that tans only offer protection equivalent to using factor 3 sunscreen 100, 101.

Fake tan

'Fake tan' lotions, sprays, creams and mousses are topical products containing the active ingredient dihydroxyacetone (DHA), typically in concentrations of between three and five per cent 102, 103. DHA is a type of carbohydrate which reacts with the amino acids in the top layer of the skin, to form brown-black compounds called melanoidins 102, 104. The depth of the colour change is related to DHA concentration 103. DHA-containing 'fake tan' products are considered to be non-toxic 103, 104.

Bronzers do not contain the active ingredient DHA and so the colour delivered through these products, for example in the form of tinted moisturisers and powders, can be removed with the aid of soap and water 102.

The FDA (Food and Drug Administration) in the US has approved the use of DHA-containing products for the pigmentation of skin where the products are applied by hand for this allows control over the application process, and the avoidance of the mucous membranes and the area of the eye 105.

Some DHA-containing products also contain sunscreen, but at most a fake tan will only provide the same protection as an SPF4 sunscreen 106, 107. And the protection they offer will last for hours and not for the duration of the colour pigmentation, so regular application of sunscreen is still needed 103

Vitamin D

Our bodies produce vitamin D when our skin is exposed to UV rays from the sun. This is the main source of this vitamin 47. We all need vitamin D to build and maintain strong bones. If you are lacking in vitamin D for a long time then your bones may soften. In serious cases this leads to rickets in children and a condition called osteomalacia in adults 108.

Most people in the UK only need to spend a short amount of time in the sun to make enough vitamin D 109, 110, 111. This is typically less that the time taken to lead to sunburn 112. It should be possible for most people to find a balance between enjoying the beneficial effects of the sun while not increasing the risk of skin cancer.

Once a person makes enough vitamin D, any extra is turned into inactive substances 113. So heavy sun exposure does not improve vitamin D levels beyond a maximum threshold, but it can increase the risk of skin cancer 114. Even leading vitamin D researchers advise using sun protection, such as SPF sunscreens, during long or heavy exposures109.

Vitamin D synthesis is much lower in winter months in countries at higher latitudes like the UK 115. But as long as normal vitamin D level has been built up in the summer, studies show that this will combine with stored vitamin D in fatty tissue to prevent deficiency in the winter 115, 116.

Some groups have a higher risk of vitamin D deficiency, including: 

  • people with naturally brown or black skin, who need more UV radiation to increase their vitamin D levels than Caucasians 117, 118, 119, 120.
  • people who wear clothing that fully conceals them 120, 121.
  • older people who don't go outside much, since they have a reduced ability to make vitamin D through their skin 109, 117.
  • pregnant women and breast-feeding babies with vitamin D-deficient mothers 122.

The Government recommends that people at risk of vitamin D deficiency should take vitamin D supplements of 10µg a day for adults and 7µg a day for children 123.

In 2010 Cancer Research UK teamed up with other health organisations to bring together evidence on the important but controversial topic of vitamin D. It is endorsed by the British Association of Dermatologists, Cancer Research UK, Diabetes UK, the Multiple Sclerosis Society, the National Heart Forum, the National Osteoporosis Society and the Primary Care Dermatology Society.

Download the Vitamin D consensus statement

 

Early detection of skin cancer

Survival for malignant melanoma is strongly related to stage of the disease at diagnosis 124. So getting it diagnosed and treated early could make a real difference to the outcome.

One-year relative survival is highest for patients presenting at stage I, with 101% of men and women surviving for at least one year. In comparison, one-year survival is considerably lower for those diagnosed with stage IV disease (10% for men and 35% for women). As very few patients are diagnosed at stage IV, however, the one-year survival statistics have wide confidence intervals and should therefore be interpreted with caution.

The following can be a sign of skin cancer 125, 126, 127:

  • a change such as a new mole, or any moles, freckles or patches of normal skin that change in size, shape or colour.
  • a new growth or sore that will not heal.
  • a spot, mole or sore that itches or hurts.
  • a mole or growth that bleeds, crusts or scabs.

The ABCD (Asymmetry, Border, Colour, Diameter) rule outlines some key skin changes that could be a sign of melanoma skin cancer 128:

  • Asymmetry The two halves of the mole do not look the same.
  • Border The edges of the mole are irregular, blurred or jagged.
  • Colour The colour of the mole is uneven, with more than one shade.
  • Diameter The mole is wider than 6mm in diameter (the size of a pencil eraser).
 

References

  1. International Agency for Research on Cancer. Solar and ultraviolet radiation (Vol 55). Monographs on the evaluation of carcinogenic risks to humans. Lyon: IARC Press; 1992. Link 
  2. Leiter U, Garbe C. Epidemiology of melanoma and non melanoma skin cancer--the role of sunlight. Adv Exp Med Biol 2008;624:89-103. PubMed 
  3. Cogliano VJ, Baan R, Straif K, et al. Preventable exposures associated with human cancers. J Natl Cancer Inst 2011;103:1827-39. PubMed 
  4. Parkin DM, Mesher D, Sasieni P. 13. Cancers attributable to solar (ultraviolet) radiation exposure in the UK in 2010. Br J Cancer 2011;105 Suppl 2:S66-9.  PubMed 
  5. Lucas RM, McMichael AJ, Armstrong BK, et al. Estimating the global disease burden due to ultraviolet radiation exposure. International Journal of Epidemiology 2008;37:654-67. PubMed 
  6. Gandini S, Sera F, Cattaruzza MS, et al. Meta-analysis of risk factors for cutaneous melanoma: II. Sun exposure. European Journal of Cancer 2005;41:45-60. PubMed 
  7. Bauer A, Diepgen TL, Schmitt J. Is occupational solar ultraviolet irradiation a relevant risk factor for basal cell carcinoma? A systematic review and meta-analysis of the epidemiological literature. Br J Dermatol 2011;165:612-25. PubMed 
  8. Schmitt J, Seidler A, Diepgen TL, Bauer A. Occupational ultraviolet light exposure increases the risk for the development of cutaneous squamous cell carcinoma: a systematic review and meta-analysis. Br J Dermatol 2011;164:291-307.  PubMed 
  9. Pelucchi C, Di Landro A, Naldi L, et al. Risk factors for histological types and anatomic sites of cutaneous basal-cell carcinoma: an italian case-control study. J Invest Dermatol 2007;127:935-44. PubMed 
  10. Corona R, Dogliotti E, D'Errico M, et al. Risk factors for basal cell carcinoma in a Mediterranean population: role of recreational sun exposure early in life. Arch Dermatol 2001;137:1162-8. PubMed 
  11. Gallagher, R., et al., Sunlight exposure, pigmentation factors, and risk of nonmelanocytic skin cancer. II. Squamous cell carcinoma. Arch Dermatol, 1995. 131: p. 164-9. PubMed 
  12. Rhodes, A., et al., Risk factors for cutaneous melanoma. A practical method of recognizing predisposed individuals. JAMA, 1987. 258: p. 3146-54. PubMed 
  13. Tucker, M.A. and A.M. Goldstein, Melanoma etiology: where are we? Oncogene, 2003. 22(20): p. 3042-52. PubMed
  14. Gandini, S., et al., Meta-analysis of risk factors for cutaneous melanoma: I. Common and atypical naevi. Eur J Cancer, 2005. 41(1): p. 28-44. PubMed 
  15. Gandini, S., et al., Meta-analysis of risk factors for cutaneous melanoma: III. Family history, actinic damage and phenotypic factors. Eur J Cancer, 2005. 41(14): p. 2040-59. PubMed 
  16. Olsen CM, Zens MS, Green AC, et al. Biologic markers of sun exposure and melanoma risk in women: Pooled case–control analysis. Int J Cancer 2011;129:713-23. PubMed 
  17. Balamurugan A, Rees JR, Kosary C, et al. Subsequent primary cancers among men and women with in situ and invasive melanoma of the skin. J Am Acad Dermatol 2011;65:S69-77. PubMed 
  18. Bradford PT, Freedman DM, Goldstein AM, et al. Increased risk of second primary cancers after a diagnosis of melanoma. Arch Dermatol 2010;146:265-72.  PubMed 
  19. Olsen CM, Carroll HJ, Whiteman DC. Familial melanoma: a meta-analysis and estimates of attributable fraction. Cancer Epidemiol Biomarkers Prev 2010;19:65-73. PubMed 
  20. Gandini S, Sera F, Cattaruzza MS, et al. Meta-analysis of risk factors for cutaneous melanoma: III. Family history, actinic damage and phenotypic factors. Eur J Cancer 2005;41:2040-59. PubMed 
  21. National Cancer Intelligence Network and Cancer Research UK. Cancer incidence and survival by major ethnic group, England, 2002-2006. London: NCIN; 2009. Link 
  22. NCI, SEER Cancer Statistics Review, 1998-2002. Link 
  23. Scotto, J., T. Fears, and J.J. Fraumeni, Incidence of nonmelanoma skin cancer in the United States. 1983, Bethseda, MD.: National Cancer Institute, National Institutes of Health.
  24. Crombie, I.K., Racial differences in melanoma incidence. Br J Cancer, 1979. 40(2): p. 185-93. PubMed 
  25. http://www.who.int/uv/intersunprogramme/activities/uv_index/en/index.html
  26. World Health Organization, Global Solar UV Index: A Practical Guide (2002)
  27. Hiom, S. Public awareness regarding UV risks and vitamin D--the challenges for UK skin cancer prevention campaigns.. Prog Biophys Mol Biol. 2006 Sep;92(1):161-6 PubMed 
  28. Thieden et al. UV radiation exposure related to age, sex, occupation, and sun behavior based on time-stamped personal dosimeter readings. Arch Dermatol. 2004 Feb;140(2):197-203 PubMed 
  29. Schmucki, D. and R. Philipona, Ultraviolet radiation in the alps: The altitude effect. Optical Engineering, 2002. 41(12). Journal
  30. Schafer, J.S., et al., Observed influence of clouds on ultraviolet-B radiation. Geophys Res Lett, 1996. 23(19): p. 2625-2628. Journal
  31. Chen, D., et al., Attenuation of biologically effective UV doses under overcast skies: A case study from the eastern Atlantic sector of the Southern Ocean. Deep-Sea Research Part II: Topical Studies in Oceanography, 2004. 51(22-24): p. 2673-2682. Science Direct 
  32. Lee, Y., et al., Effects of ozone, cloud and snow on surface UV irradiance. Ocean Polar Res, 2004. 26(3): p. 439-451. Journal
  33. Renaud, A., et al., Influence of snow and clouds on erythemal UV radiation: Analysis of Swiss measurements and comparison with models. Journal of Geophysical Research D: Atmospheres, 2000. 105(D4): p. 4961-4969. Journal
  34. Feister, U. and Grewe, R., Spectral Albedo Measurements in the UV and Visible Region Over Different Types of Surfaces. Photochem Photobiol, 1995. 62(4): p.736-744. Journal 
  35. Olsen CM, Carroll HJ, Whiteman DC. Estimating the attributable fraction for melanoma: a meta-analysis of pigmentary characteristics and freckling. Int J Cancer 2010;127:2430-45. PubMed 
  36. Fitzpatrick T. Soleil et peau. J Med Esthet 1975;2:33-4.
  37. Health Protection Agency Information Sheet 
  38. Health Protection Agency Understanding Radiation Topic 
  39. Holloway L. Shadow method for sun protection. Lancet. 1990 Feb 24;335(8687): 484. PubMed 
  40. Gilchrest, B., et al., The pathogenesis of melanoma induced by ultraviolet radiation. N Engl J Med, 1999. 340: p. 1341-8. PubMed  
  41. Pfeifer GP et al. Mutations induced by ultraviolet light. Mutat Res. 2005 Apr 1;571(1-2):19-31 PubMed  
  42. Wlaschek M et al. Solar UV irradiation and dermal photoaging. J Photochem Photobiol B. 2001 Oct;63(1-3):41-51. PubMed  
  43. Scharffetter-Kochanek K et al. Photoaging of the skin from phenotype to mechanisms. Exp Gerontol. 2000 May;35(3):307-16. PubMed 
  44. Ridley AJ, Whiteside JR, McMillan TJ, Allinson SL. Cellular and sub-cellular responses to UVA in relation to carcinogenesis. Int J Radiat Biol. 2009 Mar;85(3):177-95. Pubmed 
  45. Elwood JM, Jopson J. Melanoma and sun exposure: an overview of published studies. Int J Cancer 1997;73:198-203. PubMed  
  46. Dennis LK, Vanbeek MJ, Beane Freeman LE, et al. Sunburns and risk of cutaneous melanoma: does age matter? A comprehensive meta-analysis. Ann Epidemiol 2008;18:614-27. PubMed 
  47. International Agency for Research on Cancer. IARC Handbook on Cancer Prevention Vol.5: Sunscreens. 2001. Link  
  48. Webb AR, Engelsen O., Ultraviolet exposure scenarios: risks of erythema from recommendations on cutaneous vitamin D synthesis. Adv Exp Med Biol 2001;p 624: 72-85 PubMed 
  49. Gange RW, Parrish JA., Acute effects of ultraviolet radiation upon the skin. In: Parrish JA, Kripke ML, & Morison WL., eds, Photoimmunology 1983, New York Plenum Press, pp 77-94 
  50. Cancer Research UK press release 2013
  51. World Health Organisation Link
  52. Linos E, Keiser E, Fu T, Colditz G, Chen S, Tang JY. Hat, shade, long sleeves, or sunscreen? Rethinking US sun protection messages based on their relative effectiveness. Cancer Causes Contro. 2011 Jul;22(7):1067-71. PubMed 
  53. Autier P, et al. Sunscreen use, wearing clothes, and number of nevi in 6- to 7-year-old European children. European Organization for Research and Treatment of Cancer Melanoma Cooperative Group. J Natl Cancer Inst. 1998 Dec 16;90(24):1873-80. PubMed  
  54. Lazovich D et al. Melanoma risk in relation to use of sunscreen or other sun protection methods. Cancer Epidemiol Biomarkers Prev. 2011 Dec;20(12):2583-93. PubMed
  55. Parsons PG, Neale R, Wolski P, Green A. The shady side of solar protection. Medical Journal
    of Australia 1998; 168(7): 327-30. PubMed 
  56. Saraiya, M., et al., Interventions to prevent skin cancer by reducing exposure to ultraviolet radiation: a systematic review. Am J Prev Med, 2004. 27: p. 422-66. PubMed 
  57. NRPB, et al., Protection from UVR by Clothing. 1998. Link   
  58. Diffey, B.L. and J. Cheeseman, Sun protection with hats. Br J Dermatol, 1992. 127(1): p. 10-2. PubMed 
  59. Davis, S., et al., Clothing as protection from ultraviolet radiation: which fabric is most effective? Int J Dermatol, 1997. 36(5): p. 374-9. PubMed 
  60. Sakamoto, Y., M. Kojima, and K. Sasaki, Effectiveness of eyeglasses for protection against ultraviolet rays. Nippon Ganka Gakkai Zasshi, 1999. 103(5): p. 379-85. PubMed 
  61. Pion, I., Educating children and parents about sun protection. Dermatol Nurs, 1996. 8: p. 29-36. PubMed  
  62. Green AC, Williams GM, Logan V, Strutton GM. Reduced melanoma after regular sunscreen
    use: randomized trial follow-up. Journal of Clinical Oncology 2011; 29(3): 257-63. PubMed 
  63. Chesnut C, Kim J. Is there truly no benefit with sunscreen use and Basal cell carcinoma? A critical review of the literature and the application of new sunscreen labeling rules to real-world sunscreen practices. J Skin Cancer 2012;2012:480985. PubMed  
  64. Diffey BL. Sunscreens as a preventative measure in melanoma: an evidence-based approach or the precautionary principle? Br J Dermatol 2009;161:25-7. PubMed  
  65. Editorial 2011. Do sunscreens have a role in preventing skin cancer? Drug and Therapeutics Bulletin. 49 (6) 69-72. PubMed 
  66. Autier P, Boniol M, Doré JF. Sunscreen use and increased duration of intentional sun exposure: still a burning issue. Int J Cancer. 2007 Jul 1;121(1):1-5. Review. PubMed 
  67. Autier P. Sunscreen abuse for intentional sun exposure. British Journal of Dermatology 2009; 161 Suppl 3: 40-5 PubMed  
  68. Diffey, B., Has the sun protection factor had its day? BMJ, 2000. 320: p. 176-7. PubMed

  69. NICE http://guidance.nice.org.uk/PH32

  70. De Villa D et al. 2011. Re-application improves the amount of sunscreen, not its regularity, under real life conditions. Photochemistry and Photobiology. 87. 457-60. PubMed  
  71. Diffey BL. People do not apply enough sunscreen for protection. British Medical Journal 1996;
    313: 942. PubMed   
  72. Stenberg, C. and O. Larko, Sunscreen application and its importance for the sun protection factor. Arch Dermatol, 1985. 121: p. 1400-2. PubMed 
  73. Diffey B. Sunscreen isn't enough. J Photochem Photobiol B. 2001 Nov 15;64(2-3):105-8 PubMed  
  74. Diffey, B., When should sunscreen be reapplied? J Am Acad Dermatol, 2001. 45: p. 882-5. PubMed   
  75. Prium, B., L. Wright, and A. Green, Do people who apply sunscreens, reapply them? Australas J Dermatol, 1999. 40(2): p. 79-82. PubMed 
  76. Pissavini M, Diffey B. 2013. The likelihood of sunburn in sunscreen users is disproportionate to the SPF. Photodermatology, photoimmunology and photomedicine. 29 (3) 111-5. PubMed 
  77. Schneider J. The teaspoon rule of applying sunscreen. Archives of Dermatology 2002; 138(6): 838-9. PubMed 
  78. Bens G. Sunscreens. Adv Exp Med Biol. 2008;624:137-61. PubMed  
  79. Armstrong BK. How sun exposure causes skin cancer: An epidemiological perspective. In: Hill D., Elwood J. M. and English D. R. (Eds). Prevention of Skin Cancer. Dordrecht, The Netherlands: Kluwer Academic Publishers, 2004, pp. 89-116. 
  80. Erdmann F, Lortet-Tieulent J, Schüz J, Zeeb H, Greinert R, Breitbart EW, Bray F.
    International trends in the incidence of malignant melanoma 1953–2008—are recent generations at higher or lower risk? International Journal of Cancer 2012 PubMed 
  81. Whiteman, D., C. Whiteman, and A. Green, Childhood sun exposure as a risk factor for melanoma: a systematic review of epidemiologic studies. Cancer Causes Control, 2001. 12: p. 69-82. PubMed 
  82. Dobbinson S, Wakefield M, Hill D, Girgis A, Aitken JF, Beckmann K, Reeder AI, Herd N, Spittal MJ, Fairthorne A, Bowles K-A. Children's sun exposure and sun protection: Prevalence in Australia and related parental factors. Journal of the American Academy of Dermatology 2012; 66(6): 938-47. PubMed  
  83. Hill, D. and Dixon, H. (1999) Promoting sun protection in children: rationale and challenges. Health Education and Behavior, 26, 409–417. PubMed 
  84. World Health Organization. Sunshine and health: how to enjoy the sun safely. Available at: www.who.int/uv/publications/solaruvflyer2006.pdf
  85. American Academy of Pediatrics, Committee on Environmental Health. Ultraviolet light: a hazard to children. Pediatrics. 1999;104(2 pt 1):328–333 PubMed  
  86. Wehner MR, Shive ML, Chren MM, et al. Indoor tanning and non-melanoma skin cancer: systematic review and meta-analysis. BMJ 2012;345:e5909. doi: 10.1136/bmj.e5909. PubMed 
  87. Boniol M, Autier P, Boyle P, Gandini S. Correction to Cutaneous melanoma attributable to sunbed use: systematic review and meta-analysis. BMJ 2012;345:e8503. Journal 
  88. Veierod MB, Weiderpass E, Thorn M, et al. A prospective study of pigmentation, sun exposure, and risk of cutaneous malignant melanoma in women. J Natl Cancer Inst 2003;95:1530–8. PubMed 
  89. Gies, H., C. Roy, and G. Elliott, Artificial suntanning: spectral irradiance and hazard evaluation of ultraviolet sources. Health Phys, 1986. 50: p. 691-703. PubMed 
  90. Gerber, B., et al., Ultraviolet emission spectra of sunbeds. Photochem Photobiol, 2002. 76: p. 664-8. PubMed 
  91. Wright, A., et al., Survey of the variation in ultraviolet outputs from ultraviolet A sunbeds in Bradford. Photodermatol Photoimmunol Photomed, 1996. 12: p. 12-6. PubMed 
  92. Gerber, B., et al., Ultraviolet emission spectra of sunbeds. Photochem Photobiol, 2002. 76: p. 664-8. PubMed  
  93. P Tierney et al, ‘Nine out of ten sunbeds in England emit UV radiation levels that exceed current safety limits’, DOI : 10.1111/bjd.12181 
  94. Autier, P., Perspectives in melanoma prevention: the case of sunbeds. Eur J Cancer, 2004. 40: p. 2367-2376. PubMed 
  95. Ma W et al. Chronological ageing and photoageing of the fibroblasts and the dermal connective tissue. Clin Exp Dermatol. 2001 Oct;26(7):592-9. PubMed 
  96. Piérard GE. Ageing in the sun parlour. Int J Cosmet Sci. 1998 Aug;20(4):251-9. doi: 10.1046/j.1467-2494.1998.176611.x PubMed 
  97. Reimann V et al. Sunbed use induces the photoaging-associated mitochondrial common deletion. J Invest Dermatol. 2008 May;128(5):1294-7.  PubMed 
  98. Pedeux, R., et al., Thymidine dinucleotides induce S phase cell cycle arrest in addition to increased melanogenesis in human melanocytes. J Invest Dermatol, 1998. 111: p. 472-7. PubMed 
  99. Eller, M., et al., Enhancement of DNA repair in human skin cells by thymidine dinucleotides: evidence for a p53-mediated mammalian SOS response. Proc Natl Acad Sci U S A, 1997. 94: p. 12627-32. PubMed 
  100. Gange, R., et al., Comparative protection efficiency of UVA- and UVB-induced tans against erythema and formation of endonuclease-sensitive sites in DNA by UVB in human skin. J Invest Dermatol, 1985. 85: p. 362-4.PubMed 
  101. Bykov, V., J. Marcusson, and K. Hemminki, Protective effects of tanning on cutaneous DNA damage in situ. Dermatology, 2001. 202: p. 22-6. PubMed 
  102. Fu JM et al. Sunless tanning. J Am Acad Dermatol. 2004 May;50(5):706-13. PubMed 
  103. Levy SB. Tanning preparations. Dermatol Clin. 2000 Oct;18(4):591-6. PubMed 
  104. Draelos ZD. Self-tanning lotions: are they a healthy way to achieve a tan? Am J Clin Dermatol. 2002;3(5):317-8. PubMed  
  105. FDA: Sunless tanners and bronzers. Link 
  106. Faurschou, A., Wulf, H.C., Durability of the sun protection factor provided by dihydroxyacetone. Photodermatology, Photoimmunology and Photomedicine, 2004. 20: p. 239-242. PubMed 
  107. Faurschou, A., Janjua, N.R., Wulf, H.C., Sun protection effect of dihydroxyacetone. Archives of Dermatology, 2004. 140: p. 886-887. PubMed 
  108. SACN. Update on Vitamin D: Position Statement  by the Scientific Advisory Committee on Nutrition. London:
    TSO; 2007 
  109. Holick, M., Sunlight "D"ilemma: risk of skin cancer or bone disease and muscle weakness. Lancet, 2001. 357: p. 4-6. PubMed 
  110. Griffiths, A.P. and A. Fairney, Effect of phototherapy on serum 25-hydroxyvitamin D in the Antarctic. Eur J Appl Physiol Occup Physiol, 1989. 59(1-2): p. 68-72. PubMed 
  111. Pitson, G.A., D.J. Lugg, and C.R. Roy, Effect of seasonal ultraviolet radiation fluctuations on vitamin D homeostasis during an Antarctic expedition. Eur J Appl Physiol Occup Physiol, 1996. 72(3): p. 231-4. PubMed 
  112. Webb, A.R. and O. Engelsen, Calculated Ultraviolet Exposure Levels for a Healthy Vitamin D Status. Photochem Photobiol, 2006. PubMed 
  113. Webb, A.R., B.R. DeCosta, and M.F. Holick, Sunlight regulates the cutaneous production of vitamin D3 by causing its photodegradation. J Clin Endocrinol Metab, 1989. 68(5): p. 882-7. PubMed 
  114. Holick, M., Vitamin D., in Modern Nutrition in Health and Disease, M.e.a. Shils, Editor. 1999, Lippincott Williams & Wilkins: New York. p. 329-346. 
  115. Heaney, R.P., et al., Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol. Am J Clin Nutr, 2003. 77(1): p. 204-10. PubMed 
  116. Beadle, P., J. Burton, and J. Leach, Correlation of seasonal variation of 25-hydroxycalciferol with UV radiation dose. Br J Dermatol, 1980. 103: p. 289-93. PubMed 
  117. Dawson-Hughes, B., Racial/ethnic considerations in making recommendations for vitamin D for adult and elderly men and women. Am J Clin Nutr, 2004. 80: p. 1763S-6S. PubMed 
  118. Shaw, N. and B. Pal, Vitamin D deficiency in UK Asian families: activating a new concern. Archives of Disease in Childhood, 2002. 86: p. 147-149. PubMed 
  119. Glerup, H., et al., Commonly recommended daily intake of vitamin D is not sufficient if sunlight exposure is limited. J Intern Med, 2000. 247: p. 260-8. PubMed 
  120. MacLaughlin, J. and M. Holick, Aging decreases the capacity of human skin to produce vitamin D3. J Clin Invest, 1985. 76: p. 1536-8. PubMed 
  121. Holick, M., L. Matsuoka, and J. Wortsman, Age, vitamin D, and solar ultraviolet. Lancet, 1989. 2: p. 1104-5. PubMed
  122. Hatun, S., et al., Vitamin D deficiency in early infancy. J Nutr, 2005. 135: p. 279-82. PubMed 
  123. https://www.gov.uk/government/publications/vitamin-d-advice-on-supplements-for-at-risk-groups (accessed February 2014) 
  124. The National Cancer Registration Service, Eastern Office. Personal communication. 
  125. NICE http://guidance.nice.org.uk/CG27/Guidance 
  126. Keefe M, Dick DC, Wakeel RA. A study of the value of the seven-point checklist in distinguishing benign pigmented lesions from melanoma.  Clin Exp Dermatol. 1990 May;15(3):167-71. PubMed

  127.  MacKie RM. Clinical recognition of early invasive malignant melanoma. BMJ. 1990 Nov 3;301(6759):1005-6. PubMed

  128. Rigel DS, Russak J, Friedman R. The evolution of melanoma diagnosis: 25 years beyond the ABCDs. CA Cancer J Clin. 2010 Sep-Oct;60(5):301-16. doi: 10.3322/caac.20074. Epub 2010 Jul 29. PubMed