The consequences for human health of stratospheric ozone depletion in association with other environmental factors.
Photochem Photobiol Sci. 2014 Nov 10. [Epub ahead of print]
Lucas RM1, Norval M, Neale RE, Young AR, de Gruijl FR, Takizawa Y, van der Leun JC.
1National Centre for Epidemiology and Population Health, The Australian National University, Canberra 2601, Australia. robyn.lucas at anu.edu.au.
Due to the implementation of the Montreal Protocol, which has limited, and is now probably reversing, the depletion of the stratospheric ozone layer, only modest increases in solar UV-B radiation at the surface of the Earth have occurred.
For many fair-skinned populations, changing behaviour with regard to exposure to the sun over the past half century - more time in the sun, less clothing cover (more skin exposed), and preference for a tan - has probably contributed more to greater levels of exposure to UV-B radiation than ozone depletion.
Exposure to UV-B radiation has both adverse and beneficial effects on human health.
This report focuses on an assessment of the evidence regarding these outcomes that has been published since our previous report in 2010.
The skin and eyes are the organs exposed to solar UV radiation. Excessive solar irradiation causes skin cancer, including cutaneous malignant melanoma and the non-melanoma skin cancers, basal cell carcinoma and squamous cell carcinoma, and contributes to the development of other rare skin cancers such as Merkel cell carcinoma.
Although the incidence of melanoma continues to increase in many countries, in some locations, primarily those with strong sun protection programmes, incidence has stabilised or decreased over the past 5 years, particularly in younger age-groups.
However, the incidence of non-melanoma skin cancers is still increasing in most locations. Exposure of the skin to the sun also induces systemic immune suppression that may have adverse effects on health, such as through the reactivation of latent viral infections, but also beneficial effects through suppression of autoimmune reactivity.
Solar UV-B radiation damages the eyes, causing cataracts and pterygium. UV-B irradiation of the skin is the main source of vitamin D in many geographic locations.
Vitamin D plays a critical role in the maintenance of calcium homeostasis in the body; severe deficiency causes the bone diseases, rickets in children and osteomalacia in adults. Although many studies have implicated vitamin D deficiency in a wide range of diseases, such as cancer and cardiovascular disease, more recent evidence is less compelling, with meta-analyses of supplementation trials failing to show a beneficial effect on the health outcomes that have been tested. It continues to be difficult to provide public health messages to guide safe exposure to the sun that are accurate, simple, and can be used by people with different skin types, in different locations, and for different times of the year or day. There is increasing interest in relating sun protection messages to the UV Index. Current sun protection strategies are outlined and assessed. Climatic factors affect the amount of UV radiation received by the skin and eyes, separately from the effect of ozone depletion. For example, cloud cover can decrease or increase the intensity of UV radiation at Earth's surface and warmer temperatures and changes in precipitation patterns may alter the amount of time people spend outdoors and their choice of clothing. The combination of changes in climate and UV radiation may affect the number of pathogenic microorganisms in surface waters, and could have an impact on food security through effects on plant and aquatic systems. It remains difficult to quantify these effects and their possible importance for human health.
- Overview UV and vitamin D
- UV, sunshine, and vitamin D (87 charts) - Holick March 2013
- Cancer, Sunlight, and Vitamin D - Holick Oct 2014
- The sun provides more health benefit than vitamin D – Dr. Lucas podcast – May 2015
- Vitamin D protects DNA against UV skin damage – 5 studies 2012-2013
- Many other anti-cancer photoproducts generated on the skin in addition to vitamin D – Jan 2014
- UV Radiation and the Skin June 2013
- Melanoma is 44 percent LESS LIKELY if get sun on the job – Nov 2013
gradually increasing UV is not a problem - as the higher Vitamin D levels prevent skin damage
- Nonmelanoma skin cancer IS associated with increased risk of other cancers – March 2014
- Decreased risk of non-melanoma skin cancer by working outdoors in Europe – April 2013
- Cancer Council of Australia recommends 30 minutes of daily sunshine – June 2014
- Cancer survival 4 percent more likely with just a little more vitamin D (4 ng) - meta-analysis July 2014
- Solar UVB reduces Cancer Risk – Grant, Jan 2013
- The Anti-cancer Actions of Vitamin D – Jan 2013
- Vitamin D Supplementation and Cancer - Review of RCT Jan 2013
- More Cancer, less Solar Radiation - 1941 has been known for a long time
- Sun avoidance increases risk of death by 2X – April 2014
- Melanoma huge increase - perhaps due to use of sunscreen or lower vitamin D - Aug 2014
- Sunscreen in a pill (with low SPF)
- Overview Suntans melanoma and vitamin D