Humans
Skin Cancer

Skin cancer rates in the United States are about twice those of northern Europe. Skin cancer is now the fastest growing type of cancer among men, and the third fastest growing among women. The ability of the sun to redden skin is thought to increase 1% for each 1% decrease in ozone. However, the ability of uv radiation to damage DNA is thought to increase 2.5% for each 1% reduction in ozone.

Damage to DNA is responsible for skin cancer. Except for a variety called melanoma, skin cancer is usually easily treatable. Although the relation between uv radiation and the other types of skin cancer is well understood, its connection with melanoma is not. However, we know that melanoma rates are twice as high in southern states such asTexas and Florida as they are in northern states such as Wisconsin and Montana.

There are three major types of skin cancer. The non-melanoma types -- basal cell and squamous cell -- comprise the vast majority of skin cancers and are generally easily treatable. Information from the Total Ozone Mapping Satellite (TOMS) indicates spring and summer uv radiation has increased 5% per decade at 45N; 7%, at 55N; and 10%, at 55S. Corresponding increases in non-melanoma skin cancers are estimated to have increased from 3% at low latitudes to 39% at 55S.

But, even with the large percentage increase of uv radiation at high latitudes in the Southern Hemisphere, the rates there are still considerably less than rates at lower latitudes. Even though the greatest destruction of ozone occurs in the vicinity of Antarctica, it is clear that the amount of uv radiation reaching the surface at Ushaia (55S) during spring and summer is comparable to that reaching the ground in the vicinity of Buenos Aires (34S).

However, because organisms at these high latitudes have adapted to only low levels of uv radiation, the large percentage increase of this radiation is potentially very dangerous.

Cataracts and Other Eye Disorders Cataracts are a clouding of the lens of the eye that, if untreated, can lead to blindness. Although cataracts are easily treatable, this treatment may not be available to many people in developing countries. Consequently, UNEP estimates that a 1% decrease in ozone concentrations will cause 100,000 additional people to go blind.

Although blindness is a real threat from reduced ozone, sometimes news stories can contain exaggerations. For example, pictures of sheep in South America with a caption that read "blinded by uv radiation" were actually pictures of sheep suffering from pinkeye, a common illness.

Pterygia and pingueculae are other eye disorders that may be related to uv radiation exposure. A pterygium is a growth that begins in the corner of the eye and grows toward the cornea. Pterygia rarely cause major problems, but, if left untreated, may result in blindness. A pinguecala, which occasionally develops into a pterygium, is a yellow patch that forms on the white part of the eye.

Human Immune System Some researchers believe they have found a link between increased uvb radiation and reduced effectiveness of the human immune system, which leads to reduced effectiveness of inoculations as well as increased susceptibility to infections.

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