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Here is an essay on ‘Radiation and Cancer’ which states – How several types of radiation triggers the development of cancer.
Like carcinogenic chemicals, radiation is another source of cancer risk routinely encountered in the environment. Radiation is defined simply as energy traveling through space. There are many different types of radiation, each defined by its wavelength and energy content. Natural sources of radiation include ultraviolet radiation from the sun, cosmic rays from outer space, and emissions from naturally occurring radioactive elements.
Medical, industrial, and military activities have created additional sources of radiation, mainly in the form of X-rays and radioactivity. Among the various types of radiation, two main classes have been clearly identified as causes of cancer- ultraviolet radiation and ionizing radiation.
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The ability of ultraviolet radiation to cause cancer was first deduced from the observation that skin cancer is most prevalent in people who spend long hours in the sun and is more frequent in geographical areas where the sunlight is especially intense. Because ultraviolet radiation is absorbed by normal skin pigments, dark-skinned individuals have lower rates of skin cancer than do fair-skinned individuals.
Exposure to sunlight rarely causes any type of malignancy other than skin cancer because ultraviolet radiation is too weak to pass through the skin and into the interior of the body. Fortunately, the most common types of skin cancer rarely metastasize, and their superficial location makes these cancers relatively easy to remove surgically.
Ionizing radiation poses a more serious cancer hazard because it is strong enough to penetrate through the skin and reach internal organs. The first type of ionizing radiation found to be a cancer hazard was X-rays, which were discovered in 1895 by Wilhelm Roentgen. Shortly thereafter, people working with X-rays began to develop cancer in unexpectedly high numbers.
The suspicion that radiation had caused these cancers was soon confirmed by studies showing that animals exposed to X-rays develop cancer at rates that are directly related to the dose of radiation received. Another form of ionizing radiation, called nuclear radiation, is emitted by radioactive elements.
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Among the earliest scientists to work with nuclear radiation was Marie Curie who, along with her husband Pierre Curie, discovered the radioactive elements polonium and radium in 1898. She later died of a form of leukemia that we now know can be caused by high-dose exposure to ionizing radiation.
Some human populations, such as the atomic bomb survivors in Japan, have experienced very high doses of ionizing radiation, but the main exposure for most people comes from low-dose sources of natural background radiation, such as the radioactive radon gas that seeps from the earth’s crust.
Like most carcinogenic chemicals, cancer-causing forms of radiation create DNA damage and mutations.
