Sun Protection Skin Health
Posted by ecostinger on 14th Aug 2014
Health Effects of UV Radiation Exposure
Prolonged human exposure to solar UV radiation may result in acute and chronic health effects on the skin, eye and immune system. Sunburn (erythema) is the best-known acute effect of excessive UV radiation exposure. Over the longer term, UV radiation leads to premature skin aging. Another long-term effect is an inflammatory reaction of the eye. In the most serious cases, skin cancer and cataracts can occur.
It is a popular misconception that only fair skinned people need to be concerned about overexposure to the sun. Darker skin has more protective melanin pigment, and the incidence of skin cancer is lower in dark skinned people. Nevertheless, skin cancers do occur with this group and unfortunately they are often detected at a later, more dangerous stage. The risk of UV radiation-related health effects on the eye and immune system is independent of skin type.
Chronic effects include two major public health problems: skin cancers and cataracts. While non-melanoma skin cancers can be surgically removed and are rarely lethal, malignant melanoma substantially contributes to mortality rates in fair-skinned populations.
SKIN
SUNBURN, SUNTAN AND SKIN AGEING
The best known acute effect of excessive UV radiation exposure is
sunburn. Another, less obvious adaptive effect is the thickening of the
outermost layers of the skin that attenuates UV radiation penetration to
the deeper layers of the skin. Both changes are a sign of damage to the
skin. Depending on their skin type, individuals vary greatly in their
skin’s initial threshold for sunburn and their ability to adapt to UV
exposure. UV radiation accelerates skin ageing, and the gradual loss of
the skin’s elasticity results in wrinkles and dry, coarse skin.
NON-MELANOMA SKIN CANCERS
Non-melanoma skin cancers comprise basal cell carcinoma and squamous
cell carcinoma. These are rarely lethal but surgical treatment is
painful and often disfiguring. Non-melanoma skin cancers are most
frequent on parts of the body that are commonly exposed to the sun such
as ears, face, neck and forearms. This implies that long-term, repeated
UV radiation exposure is a major causal factor.
MALIGNANT MELANOMA
Malignant melanoma (MM), although far less prevalent than NMSC, is the
major cause of death from skin cancer and is more likely to be reported
and accurately diagnosed. A large number of studies indicate
that the risk of malignant melanoma correlates with genetic and personal
characteristics, and a person’s UV radiation exposure behaviour.
EYE
Cataracts are the leading cause of blindness in the world. Proteins in
the eye’s lens unravel, tangle and accumulate pigments that cloud the
lens and eventually lead to blindness. Even though cataracts appear to
different degrees in most individuals as they age, sun exposure, in
particular exposure to UVB, appears to be a major risk factor for
cataract development.
IMMUNE SYSTEM
Beyond its role in the initiation of skin cancer, sun exposure may
reduce the body’s defences that normally limit the progressive
development of skin tumours. Several studies have demonstrated that
exposure to environmental levels of UV radiation alters the activity and
distribution of some of the cells responsible for triggering immune
responses in humans. Consequently, sun exposure may enhance the risk of
infection with viral, bacterial, parasitic or fungal infections, which
has been demonstrated in a variety of animal models.
Furthermore, especially in countries of the developing world, high UV
radiation levels may reduce the effectiveness of vaccines.
Since many vaccine-preventable diseases are extremely infectious, any
factor that results in even a small decrease in vaccine efficacy can
have a major impact on public health.
OZONE DEPLETION AND UV RELATED HEALTH EFFECTS
Depletion of the ozone layer is likely to aggravate existing health
effects caused by exposure to UV radiation, as stratospheric ozone is a
particularly effective UV radiation absorber. As the ozone layer gets
thinner, the protective filter provided by the atmosphere is
progressively reduced. Consequently, human beings and the environment
are exposed to higher UV radiation levels, and especially higher UVB
levels that have the greatest impact on human health, animals, marine
organisms and plant life, hence the need for
sun protection cover when possible.
Computational models predict that a 10% decrease in stratospheric ozone could cause an additional 300 000 non-melanoma and
4500 melanoma skin cancers and between 1.6 and 1.75 million more cases of cataracts worldwide every year.