Are current guidelines for sun protection optimal for health? Exploring the evidence

Abstract

Exposure of the skin to ultraviolet (UV) radiation is the main risk factor for skin cancer, and a major source of vitamin D, in many regions of the world. Sun protection messages to minimize skin cancer risks but avoid vitamin D deficiency are challenging, partly because levels of UV radiation vary by location, season, time of day, and atmospheric conditions. The UV Index provides information on levels of UV radiation and is a cornerstone of sun protection guidelines. Current guidelines from the World Health Organization are that sun protection is required only when the UV Index is 3 or greater. This advice is pragmatic rather than evidence based. The UV Index is a continuous scale; more comprehensive sun protection is required as the UV Index increases. In addition, a wide range of UVA doses is possible with a UVI of 3, from which there may be health consequences, while full sun protection when the UVI is "moderate" (between 3 and 5) may limit vitamin D production. Finally, the duration of time spent in the sun is an essential component of a public health message, in addition to the intensity of ambient UV radiation as measured by the UV Index. Together these provide the dose of UV radiation that is relevant to both skin cancer genesis and vitamin D production. Further education is required to increase the understanding of the UV Index; messages framed using the UV Index need to incorporate the importance of duration of exposure and increasing sun protection with increasing dose of UV radiation.

Assessment of Biologically Effective Solar Ultraviolet Exposures for Court Staff and Competitors During a Major Australian Tennis Tournament

“…The standard erythemal dose (SED) has subsequently been adopted by many researchers as an additional standard measurement tool, where 1 SED = 100 Jm −2 erythemally effective radiation . The conversion between the commonly reported UVI to hourly erythemal dose (SED h −1 ) has been described by the ICNIRP and Lucas et al as being:…”

“…Both long-term chronic and short-term and intermittent intensive exposure to UVR are primarily responsible for the development of non-melanoma skin cancers (NMSC) and melanoma in the Australian population (2,3,8,9,(14)(15)(16). Additionally, repeated suberythemal UVR doses can cause cumulative mutational damage (6,(17)(18)(19). UVR overexposure can also lead to eye conditions, such as cataracts and pterygium (9,19).…”

“…Additionally, repeated suberythemal UVR doses can cause cumulative mutational damage (6,(17)(18)(19). UVR overexposure can also lead to eye conditions, such as cataracts and pterygium (9,19). Research also suggests that significant UVR exposure occurs in a person's younger years, before adulthood, which often leads to long-term negative health effects (1)(2)(3)8,20,21).…”

Sunburn and sun protection in black skin

“…Yet for countries at latitudes greater than 40°N (or S), the maximum UV Index is about 10, and sun protection is generally recommended when the UV Index is higher than 3 . A UV Index of 10 on white skin is equivalent to a UV Index of around 1 on black skin, well below the threshold when sun protection is recommended.…”

“…2 Yet for countries at latitudes greater than 40°N (or S), the maximum UV Index is about 10, and sun protection is generally recommended when the UV Index is higher than 3. 3 A UV Index of 10 on white skin is equivalent to a UV Index of around 1 on black skin, well below the threshold when sun protection is recommended. Indeed, using sun protection assiduously by people with black skin who live in countries of low insolation may be detrimental to health as it can limit the production of vitamin D.…”