The sun, its what keeps the world alive, but kills it at the same time. Earth is
protected from UV light and harmful radiation by the ozone layer, which is
depleting at an alarming rate. This depletion has allowed more dangerous UV-B
radiation to reach the Earth's surface. Although the ozone does block out most of
the damaging UV-B radiation, a small amount still reaches the Earth, causing
problems for humans. UV radiation causes such problems as climate changes,
health risks, and ecosystem changes.
UV exposure accounts for many health problems such as aging, sunburns,
skin cancer, cataracts and the weakening of the immune system. Skin cancer has
become the most prevalent type of cancer in the U.S today. According to the
American Cancer Society 40 to 50% of Americans who live to the age of 65 will
develop skin cancer at least once (American Cancer Society).
Skin cancer is a disease where cancer cells are found in the outter layer of the
skin. There are three layers of the skin; the epidermis, the dermis and the subcutis.
The epidermis is a thin layer which protects the deeper layers of the skin. It
contains three kinds of cells; flat, scaly cells on the surface called squamous cells,
round cells called basal cells and melanocytes cells which give the skin its colour.
The dermis is a thicker layer which contains blood vessels, nerves and sweat glands.
This is also the layer from which hair grows. The dermis makes sweat which helps
cool the body. Skin cancer develops in the top layer, which is the epidermis.
There are two types of skin cancer, melanomous and non-melanoumous.
Both types of these cancers develop in the cells of the epidermis. Non-melanomous
cancers develop in the basal and squamous cells. About 75% of all skin cancers are
in basal cells. (Emmet J) This type of skin cancer tends to grow slowly and found in
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