Radio-active pollutants are not like other pollutants which are sooner or later converted into harmless material and degraded into simpler constituents to be recycled into the ecosystem and used again.
It is not the element itself, but the instability of its nuclei which is responsible for damages caused by these pollutants. As long as radiations continue, these wastes are dangerous for the living beings.
After the emission of radiations nuclei attain stable state and behave like any other element in the environment or the biosphere. Life on earth’s crust could evolve only when the nuclear activity ceased, atoms acquired stable state and radiations were reduced to the level which could be tolerated by living beings. Major hazards associated with radio-active pollution can be summed up as follows:
(1) No physical, chemical or biological process can influence the process of radio-active emissions. The unstable nuclei have to decay and acquire a stable state.
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(2) A number of radio-active isotopes have a very long half-life. Thorium-232 (90Th232) takes 14,000,000,000 years to lose half of its radio-activity. Half of Uranium-235 (92U235) takes 710,000 years to disintegrate. Half ofNeptunium-237 (93Np237) decays in 2,100,000 years. This makes these radio-active wastes almost a permanent hazard for the biosphere.
(3) Most of the radiations have a high penetrating power. Thick sheets of steel, cement concrete walls etc. can not contain them. They can easily penetrate to deep seated organs and cause injury.
(4) Nucleic acids (DNA & RNA) effectively absorb these radiations. Even low level radiations which do not cause any visible damage are completely absorbed by nuclear material which causes carcinogenic, mutagenic and teratogenic effects.
(5) A biological system is unable to distinguish between a radio-active and a normal isotope of an element as their physical and chemical properties are similar. Radio-active isotopes are therefore, absorbed and incorporated within the bodies of living organisms as normal isotopes are. This lodges a radio-active source within the body of the organism itself.
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(6) Like any other element radio-active isotopes are also absorbed, accumulated and bio- magnified thousands of times. Thus the entire food chain becomes contaminated. Organisms al higher tropic levels may, therefore, receive a highly concentrated source of radio-active material through their food supply.
(7) There is no other way to dispose of these hazardous wastes except to store them for thousands or millions of years away from living beings. This is too long a period on human scale of time. Even the safest burial places for radio-active wastes, which represent the best of human efforts, have shown signs of leakage. At present it appears very difficult, though not impossible to store radioactive wastes away from the biosphere for such long periods.
(8) In spite of all these hazards, nuclear reactors and tests are still continuing and an increasingly large amount of radio-active wastes is accumulating every day while no solution to the problem of their safe disposal is in sight till date.