Ionising high-energy radiations such as X-rays, gamma rays and cosmic rays from any source have adverse effects on living tissues. The gonads (ovaries and testes) are very susceptible to these radiations. If gonads are damaged this may lead to sterility or to the production of off springs with a variety of malformations.
Leukemia and other cancerous diseases can also arise when an individual is exposed to these high-energy radiations. These radiations inhibit many cell functions, damage tissues and chromosomes and induce unwanted cell division. Pregnant women and growing children are more affected by these radiations. Because of this reason pregnant women and children below the age of 18 years are not allowed to enter a nuclear reactor building as they are liable to be exposed to these radiations there. The various ways by which a person may be exposed to these high-energy radiations are given below:
1. By accidents at nuclear power stations:
In nuclear power stations, nuclear fission reactions are carried out. These nuclear fission reactions produce very short wavelength X-rays and gamma rays. Under normal conditions, these radiations are not allowed to leak out. However, sometimes accidents do take place at nuclear power stations as a result of which human beings and other living bodies become exposed to these radiations. We have already witnessed two major accidents in the nuclear power stations one at Chernobyl in the erstwhile U.S.S.R. and the other at Three Miles Island in the U.S.A. The effects of these accidents on the human health are yet to be assessed.
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2. By testing nuclear weapons by use of nuclear weapons:
When nuclear weapons are tested, they are accompanied by release of these radiations. During Second World War, an atomic bomb was dropped on the city of Hiroshima in Japan. The deadly radiations released as a result of the atomic explosion killed thousands of people instantaneously. The persons who survived from many metabolic disorders such as skin lesions, cancers and chromosomal defects which are passed on to the future generations by the parents.
3. X-ray or Gamma ray units
Doctors and other persons handling X-ray or Gamma ray units are exposed to low doses of these radiations. However, prolonged exposure to even low doses of radiation may cause damage.
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4. By consuming food contaminated with radiations materials.
5. Leakage of radiations from nuclear wastes
Leakage of radiations from nuclear wastes may also expose human beings to these deadly radiations. Radioactive isotopes are produced in all nuclear fission reactions. The radiation levels produced by these isotopes are dangerous to life. At present, we do not have any fail-safe method for the disposal of this radioactive waste material. Many of these radioactive materials have half lives more than millions of years. In other words, it takes millions of years before they are converted into harmless non-radiation substances.
6. Radiations emitted by natural radioactive substances.
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It may be mentioned here that the sunlight also contains harmful radiations called ultra-violet (UV) radiations. These rays affect cell growth and interface with genetic and metabolic activities. However, the cells have some mechanisms by which they can repair some of the damage caused by ultraviolet radiations. The other two types of radiations- Visible and the infrared (IR) do not have any adverse effect on our bodies.
Radiation damages are much more serious than the common diseases because of the following reasons:
1. Most of the short wavelength radiations, which cause damage, cannot be seen by the eye and the damage caused by them is not immediately felt. As a result, one is unable to take precautionary measures well in time.
2. Damage caused by radiations to the body cells is irreversible.
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3. There is no cure for the damage caused by radiations.
4. Radiations may include hereditary changes, which are result in a variety of malformations (defects) in the future generations.