Skin cancer is caused primarily by exposure to ultraviolet (UV) radiation – either from the sun or from artificial sources such as sunbeds.
Globally in 2000, over 200 000 cases of melanoma were diagnosed and there were 65 000 melanoma-associated deaths.
Excessive sun exposure in children and adolescents is likely to contribute to skin cancer in later life.
Worldwide approximately 18 million people are blind as a result of cataracts, of these 5% of all cataract related disease burden is directly attributable to UV radiation exposure.
Sun protection is recommended when the ultraviolet index is 3 and above. Small amounts of UV radiation are beneficial to health, and play an essential role in the production of vitamin D. However, excessive exposure to UV radiation is associated with different types of skin cancer, sunburn, accelerated skin ageing, cataract and other eye diseases. There is also evidence that UV radiation reduces the effectiveness of the immune system.
Effects on the skin
Excessive UV exposure results in a number of chronic skin changes.
· Squamous cell carcinoma of the skin: a malignant cancer, which generally progresses less rapidly than melanoma and is less likely to cause death.
· Basal cell carcinoma of the skin: a slow-growing skin cancer appearing predominantly in older people.
· Photoageing: a loss of skin tightness and the development of solar keratoses.
Excessive UV exposure results in a number of chronic skin changes.
· Cutaneous malignant melanoma: a life-threatening malignant skin cancer.
· Squamous cell carcinoma of the skin: a malignant cancer, which generally progresses less rapidly than melanoma and is less likely to cause death.
· Basal cell carcinoma of the skin: a slow-growing skin cancer appearing predominantly in older people.
· Photoageing: a loss of skin tightness and the development of solar keratoses.
Effects on the eyes
Acute effects of UV radiation include photokeratitis and photoconjunctivitis (inflammation of the cornea and conjunctiva, respectively). These effects are reversible, easily prevented by protective eyewear and are not associated with any long-term damage.
Chronic effects of UV radiation include:
· Cataract: an eye disease where the lens becomes increasingly opaque, resulting in impaired vision and eventual blindness.
· Pterygium: a white or creamy fleshy growth on the surface of the eye.
Other health effects
UV radiation appears to diminish the effectiveness of the immune system by changing the activity and distribution of the cells responsible for triggering immune responses. Immunosuppression can cause reactivation of the herpes simplex virus in the lip ("cold sores").
Vulnerable groups
Children and adolescents are particularly vulnerable to the harmful effects of UV radiation. Excessive sun exposure in children is likely to contribute to skin cancer in later life. The mechanisms are unclear, but it may be that skin is more susceptible to the harmful effects of UV radiation during childhood.
A person's skin type is also important. Fair-skinned people suffer more from sunburn and have a higher risk of skin cancer than dark-skinned people.
Protective measures
Ø Limit time in the midday sun.
Ø Seek shade
Ø Wear protective clothing such as a broad brimmed hat to protect the eyes, face and neck.
Ø Wear sunglasses with side panels that provide 99 to 100 percent UV-A and UV-B protection.
Ø Use and liberally reapply broad-spectrum sunscreen of sun protection factor (SPF) 30+ on skin areas that cannot be covered by clothes. Sun protection is best achieved by seeking shade and wearing clothes rather than applying sunscreens. Sunscreens should not be used for extending time spent in the sun, and people using sunscreen during sun tanning should voluntarily limit their time spent in the sun.
Ø Avoid sunbeds: use of sunbeds before the age of 35 is associated with a 75% increase in the risk of melanoma.
Ø Protect babies and young children: always keep babies in the shade.
Ø Encouraging children to take the simple precautions above will prevent both short-term and long-term damage while still allowing them to enjoy the time they spend outdoors. Parents and guardians should ensure that children are protected adequately.
