ULTRA-VIOLET RADIATION - HARMFUL EFFECTS AND BENEFITS

Scientists across the globe who are dealing with human health would like to quantify UV exposure and the damage it causes. However this is highly complex, as varying degrees of susceptibility is attributed to the different species inhabiting the earth.

Health Concerns of UV Radiation In humans, it has been observed that prolonged exposure to solar radiation has deleterious effects on the -

Skin,

Eye

Immune system.

Severity of the damage is directly propotional to the UV wavelength, intensity and duration of exposure.

Skin: Premature ageing- UV rays can accelerate ageing by damaging the collagen fibres of the skin and thereby reducing its elasticity.

UV- A, although the least harmful, can induce the onset of premature wrinkling, also known as 'actinic degeneration', besides causing DNA damages.

Sun tan- UV-A oxidizes the melanin granules close to our skin and stimulates the production of new ones. These new granules generate a tan which is a protective mechanism to prevent further skin damage

Sun burn- Over exposure to the sun's UV-B rays may cause an injury to a blood vessel on the skin surface. This may lead to sunburn, which is the reddening and swelling of the injured area, and this may worsen after 24-72 hrs.

Melanoma- This is the most serious form of skin cancer. Studies have shown that there is a strong link between sunburn in childhood and the onset of malignant melanoma in adults.

UV B radiation causes DNA thymine base pairs to link resulting in mutations, which are the precursors of cancer. The American Cancer Society reports 44,200 new cases of melanoma and 7300 deaths each year.

Other types of skin cancer that may result from UV exposure are basal and squamous cell carcinoma.

Actinic Keratosis- Over dose of UV radiation could lead to a skin growth known as actinic kearatosis, which appears as a red and rough elevation on the skin. This commonly affects parts that are exposed to sunlight.

Eyes:

Over exposure to UV radiations are extremely hazardous to the eyes and it may result in

Photokeratitis (Welder's flash) leading to cataract,

Pinguecula formation

Pterygium.

Immune system:

Over exposure to UV rays could result in immunosuppression and this has been cited as one of the reason for cancer development in these patients