UV rays and skin cancer
The sun’s UV rays
There are 3 types of UV (ultraviolet) rays: UVA UVB and UVC
The shorter the wavelength, the greater the energy, the more harmful
The shorter wavelength UVC rays, are completely absorbed by gases
in the atmosphere and do not reach the earth’s surface. These
are the most harmful UV rays.
The medium wavelength of UVB rays are partially blocked by the
atmosphere, however some of these rays do reach the earth’s
surface, they have greater energy than UVA.
The longer wavelength of UVA rays pass almost freely through the
atmosphere and reach the earth’s surface in abundance. Although
they have less energy than UVB, about 90% to 95% of ultraviolet
rays reaching the earths surface are UVA rays.
We may see from this that protecting the Ozone layer from depletion
is vitally important to the human race.
Overexposure to these rays is known to be
UVB rays – penetrate the epidermis (the outer layer of the
skin). Overexposure to these rays causes sunburn (erythema) skin
damage and may eventually lead to all forms of skin cancers.
UVA rays – go deeper into the skin, penetrating the dermis
(the inner layer of the skin). Overexposure to these rays is the
main cause for premature ageing of the skin and is now linked to
melanoma, and possibly other forms of skin cancer.
Both of these rays initiate the release of ‘free radicals’,
in our skin.
UVB rays release in the outer layer (the epidermis).
UVA rays release in both the outer layer and the inner layer (the
Free radicals attack cell membranes and cause damage to lipids,
protein and DNA
About 90% of all skin cancers are sun related and are in the main
There are two main types of skin cancer; melanoma and non-melanoma
Melanoma (also known as
Although this is the rarest form of skin cancer it is the most dangerous
and aggressive type. This can spread to other parts of the body
and can be fatal
There is a growing concern that the incidence rate of this type
of skin cancer is rising increasingly in young people.
There are two types of non-melanoma skin cancers.
Basal cell carcinoma and Squamous cell carcinoma. These cancers
usually occur in older people and are mainly due to the accumulative
affect of overexposure to the sun.
Squamous cell carcinoma
- Is the second most common skin cancer and is the more dangerous
of the non-melanoma types. If left untreated this can spread to
other parts of the body.
Basal cell carcinoma
- The most common form of skin cancer. This rarely spreads throughout
the body but can invade neighboring bones and nerves.
Examine your body regularly. If you detect any skin abnormalities,
particularly mole changes, consult your doctor promptly.
Early detection and treatment will, in the majority of cases, provide