Ozone Layer Depletion and Emerging Public Health Concerns - An Update on Epidemiological Perspective of the Ambivalent Effects of Ultraviolet Radiation Exposure

Abstract

Solar ultraviolet (UV) radiation exposure is the primary etiological agent responsible for developing cutaneous malignancies. Avoiding excessive radiation exposure, especially by high-risk groups, is recommended to prevent UV-induced photo-pathologies. However, optimal sun exposure is essential for the healthy synthesis of about 90% of vitamin D levels in the body. Insufficient exposure to UV-B is linked to vitamin D deficiency in humans. Therefore, optimal sun exposure is necessary for maintaining a normal state of homeostasis in the skin. Humans worldwide face a major existential threat because of climate change which has already shown its effects in several ways. Over the last 4 to 5 decades, increased incidences in skin cancer cases have led international health organizations to develop strong sun protection measures. However, at the same time, a growing concern about vitamin D deficiency is creating a kind of exposure dilemma. Current knowledge of UV exposure to skin outweighs the adverse effects than the beneficial roles it offers to the body, necessitating a correct public health recommendation on optimal sun exposure. Following an appropriate recommendation on optimal sun exposure will lead to positive outcomes in protecting humans against the adverse effects of strict recommendations on sun protection measures. In this short review, we spotlight the ambivalent health effects of UV exposure and how ozone layer depletion has influenced these effects of UVR. Further, our aim remains to explore how to lead towards a balanced recommendation on sun protection measures to prevent the spurt of diseases due to inadequate exposure to UV-B.

Keywords: food fortification; ozone layer depletion; skin photodamage; sun protection measures; ultraviolet radiation (UV); vitamin D deficiency.

Figure 1

(A) Evolutionarily mediated adaptation of life forms to differential atmospheric UVR levels. UV radiation exposure requirements promoting healthy vitamin D synthesis in skin meant that people developed darker skin pigmentation at places of low latitude with high ambient UVR intensity, offering them protection from the effects of UVR. While, those at higher latitude have fairer skin as an evolutionarily developed trait to potentiate the insufficient vitamin D production from low ambient exposure of UV to skin. (B) Ambivalent effects of UVR exposure to skin. Schematic diagram showing relationship between benefits of optimum UVR exposure, ill effects of inadequate exposure and the global burden of diseases due to inappropriate UV exposure. A represents insufficient UVR exposure responsible for the improper vitamin D levels in the body leading to skeletal abnormalities and other indirect effects of low ambient UV exposure. B represents optimal UVR exposure required for the essential and healthy synthesis of vitamin D in the body and also stimulates the opioidogenic system in the brain. C shows high UVR exposure leading to skin and ocular malignancies especially, in fair-skinned individuals. Both A & C are related to inappropriate exposure of UVR to the skin.