The effects on human health from stratospheric ozone depletion and its interactions with climate change

Abstract

Ozone depletion leads to an increase in the ultraviolet-B (UV-B) component (280-315 nm) of solar ultraviolet radiation (UVR) reaching the surface of the Earth with important consequences for human health. Solar UVR has many harmful and some beneficial effects on individuals and, in this review, information mainly published since the previous report in 2003 (F. R. de Gruijl, J. Longstreth, M. Norval, A. P. Cullen, H. Slaper, M. L. Kripke, Y. Takizawa and J. C. van der Leun, Photochem. Photobiol. Sci., 2003, 2, pp. 16-28) is discussed. The eye is exposed directly to sunlight and this can result in acute or long-term damage. Studying how UV-B interacts with the surface and internal structures of the eye has led to a further understanding of the location and pathogenesis of a number of ocular diseases, including pterygium and cataract. The skin is also exposed directly to solar UVR, and the development of skin cancer is the main adverse health outcome of excessive UVR exposure. Skin cancer is the most common form of malignancy amongst fair-skinned people, and its incidence has increased markedly in recent decades. Projections consistently indicate a further doubling in the next ten years. It is recognised that genetic factors in addition to those controlling pigment variation can modulate the response of an individual to UVR. Several of the genetic factors affecting susceptibility to the development of squamous cell carcinoma, basal cell carcinoma and melanoma have been identified. Exposure to solar UVR down-regulates immune responses, in the skin and systemically, by a combination of mechanisms including the generation of particularly potent subsets of T regulatory cells. Such immunosuppression is known to be a crucial factor in the generation of skin cancers. Apart from a detrimental effect on infections caused by some members of the herpesvirus and papillomavirus families, the impact of UV-induced immunosuppression on other microbial diseases and vaccination efficacy is not clear. One important beneficial effect of solar UV-B is its contribution to the cutaneous synthesis of vitamin D, recognised to be a crucial hormone for bone health and for other aspects of general health. There is accumulating evidence that UVR exposure, either directly or via stimulation of vitamin D production, has protective effects on the development of some autoimmune diseases, including multiple sclerosis and type 1 diabetes. Adequate vitamin D may also be protective for the development of several internal cancers and infections. Difficulties associated with balancing the positive effects of vitamin D with the negative effects of too much exposure to solar UV-B are considered. Various strategies that can be adopted by the individual to protect against excessive exposure of the eye or the skin to sunlight are suggested. Finally, possible interactions between ozone depletion and climate warming are outlined briefly, as well as how these might influence human behaviour with regard to sun exposure.

Solar UV exposure in construction workers in Valencia, Spain

“…Otherwise, solar exposure is known to have positive effects on human health, such as, for example, the synthesis of Vitamin D3 (de Gruijl, 2011;Webb et al, 2011), essential for bone mineralization (Norval et al 2007). Appropriate vitamin D levels, besides being required for 6 skeletal health, have also been suggested as beneficial against multiple sclerosis (Kampman et al, 2010;Van Amerongen et al, 2004), cardiovascular disease (Zittermann and Gummert, 2010) and the development of breast, prostate and colon cancers (Gilbert et al, 2009;Grant, 2010;Grant and Holick, 2005;John et al, 2007).…”

Personal UV exposure for different outdoor sports

“…[1][2][3][4] On the other hand, sun exposure is also beneficial for human health, 2,4 as appropriate doses give beneficial physiological effects, such as the synthesis of Vitamin D, 5,6 essential for bone mineralization and skeletal health. 7 It also has beneficial effects with regard to the prevention of several diseases [8][9][10][11] and on mental health. 12 There is evidence that skin cancer and melanoma represent a public health problem in Spain and the rest of Europe since their incidence has increased significantly in the last 40 years.…”

Solar UV exposure of children in a summer school in Valencia, Spain

“…Some exposure of skin to solar UV radiation stimulates the synthesis of Vitamin D (Norval et al 2007) and is good for human well-being and required for skeletal health. This is especially important for growing children and it has been suggested that there may be beneficial properties against breast and colon cancers in adulthood (Grant and Holick 2005).…”