Radioactive contamination, also called radiological contamination, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids or gases (including the human body), where their presence is unintended or undesirable.Such contamination presents a hazard because of the radioactive decay of the contaminants, which emit harmful ionizing radiation such as alpha particles or beta particles, gamma rays or neutrons. The degree of hazard is determined by the concentration of the contaminants, the energy of the radiation being emitted, the type of radiation, and the proximity of the contamination to organs of the body. It is important to be clear that the contamination gives rise to the radiation hazard

CAUSES OF RADIATION POLLUTIONThe radiation pollution causes are various human activities, that add to natural radiation background (radiation produced everywhere in the Universe in absence of human activities).Sources of Radiation PollutionThe sources of radiation pollution involve any process that emanates radiation in the environment. While there are many causes of radiation pollution (including research and medical procedures and wastes, nuclear power plants, TVs, computers, radio waves, cell-phones, etc.), the most common ones that can pose moderate to serious health risks include:Nuclear explosions and detonations of nuclear weapons – probably the highest amounts of human-induced radiation pollution have been generated in the mid twenty century through various experimental or combat nuclear detonations (that ended the Second World War).

BEFOREAFTER

Defense weapon production – may also release radioactivity from the handled radioactive materials (usually of high health risks). However, unless accident occurs, the current standards will not allow the release of any significant amount of radiation

Mining of radioactive ores (such as uranium ores) – involve the crushing and processing of radioactive ores and generate radioactive by-products. Mining of other ores may also generate radioactive wastes (such as mining of phosphate ores).

Nuclear waste handling and disposal –The main issue with the radiation waste is the fact that it cannot be degraded or treated chemically or biologically. Thus, the only options are to contain the waste by storing it in tightly closed containers shielded with radiation-protective materials (such as Pb) or, if containing is not possible, to dilute it. The waste may also be contained by storage in remote areas with little or no life (such as remote caves or abandoned salt mines). However, in time, the shields (natural or artificial) may be damaged. Additionally, the past waste disposal practices may not have used appropriate measures to isolate the radiation. Thus, such areas need to be carefully identified and access restrictions promptly imposed.

Nuclear accidents – an already classic example of such accident is the nuclear explosion at a former Soviet nuclear power plant from Chernobyl that occurred in the mid 1986. Its effects are still seen today. Another example is the 1979 explosion at Three Mile Island nuclear-power generating plant near Harrisburg, PA. The general problems at nuclear weapons reactors are other examples of this type of sources of radiation pollution. Even accidents from handling medical nuclear materials/wastes could have radiation health effects on workers

The Chernobyl disaster was a catastrophic nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine, which was under the direct jurisdiction of the central authorities of the Soviet Union. An explosion and fire released large quantities of radioactive particles into the atmosphere, which spread over much of the western USSR and Europe.The Chernobyl disaster was the worst nuclear power plant accident in history in terms of cost and casualties, and is one of only two classified as a level 7 event (the maximum classification) on the International Nuclear Event Scale (the other being the Fukushima Daiichi nuclear disaster in 2011). The battle to contain the contamination and avert a greater catastrophe ultimately involved over 500,000 workers and cost an estimated 18 billion $USD. During the accident itself, 31 people died, and long-term effects such as cancers and deformities are still being accounted for.

In August 1945, during the final stage of the Second World War, the United States dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki. The two bombings, which killed at least 129,000 people, remain the only use of nuclear weapons for warfare in human history.

A uranium gun-type atomic bomb (Little Boy) was dropped on Hiroshima on August 6, 1945, followed by a plutonium implosion-type bomb (Fat Man) on the city of Nagasaki on August 9. Within the first two to four months of the bombings, the acute effects of the atomic bombings killed 90,000–166,000 people in Hiroshima and 39,000–80,000 in Nagasaki; roughly half of the deaths in each city occurred on the first day. During the following months, large numbers died from the effect of burns, radiation sickness, and other injuries, compounded by illness and malnutrition. In both cities, most of the dead were civilians, although Hiroshima had a sizable military garrison.

ON LAND When soil is contaminated by radioactive substances, the harmful substances are

transferred into the plants growing on it. It leads to genetic mutation and affects the plant's normal functioning. Some plants may die after such exposure, while others may develop weak seeds. Eating any part of the contaminated plant, primarily fruits, poses serious health risks. Since plants are the base of all food chains, their contamination can lead to radioactive deposition all along the food web.

ON WATER The effects of pollution on freshwater species are registered in the loss of

some species, with maybe some profits for some of them. There normally is a reduction in diversity but not necessarily numbers of individual species, and a change in the balance of such processes as predation, competition and materials cycling. Because of the complexity of pollution, the effects of take-up in the aquatic life are also depended on the pollutants characteristic feature. If two or more poisons are present together in an effluent they may exert a combined effect to an organism, which can be additive, antagonistic or synergistic.

In genetics, a mutation is a permanent change of the nucleotide sequence of the genome of an organism, virus, or extra chromosomal genetic element. Mutations result from unrepaired damage to DNA or to RNA genomes (typically caused by radiation or chemical mutagens), errors in the process of replication, or from the insertion or deletion of segments of DNA by mobile genetic elements.[1][2][3] Mutations may or may not produce discernible changes in the observable characteristics (phenotype) of an organism. Mutations play a part in both normal and abnormal biological processes including: evolution, cancer, and the development of the immune system.

The Fukushima Daiichi nuclear disaster was a nuclear disaster at the Fukushima I Nuclear Power Plant on 11

March 2011, resulting in a meltdown of three of the plant's six nuclear reactors. The failure occurred when the

plant was hit by a tsunami triggered by the magnitude 9.0Tōhoku earthquake. The plant began releasing

substantial amounts of radioactive material on 12 March, becoming the largest nuclear incident since

the Chernobyl disaster in April 1986 and the second (after Chernobyl) to measure Level 7 on the International

Nuclear Event Scale, initially releasing an estimated 10-30% of the earlier incident's radiation. In August 2013, it

was stated that the massive amount of radioactive water is among the most pressing problems affecting the

cleanup process, which is expected to take decades. There have been continued spills of contaminated water at

the plant, and some into the sea. Plant workers are trying to lower the leaks using measures such as building

chemical underground walls, but they have not yet improved the situation significantly.

The devastating quake and tsunami triggered the disaster. Nuclear fuel rods overheated and emergency cooling generators lost power when seawater flooded the buildings. This led to explosions at reactor containment buildings and leaks of nuclear material. All of the emergency response systems failed.

In the March 2011 nuclear accident, three reactors melted down after the plant lost main and backup power, paralyzing cooling systems.The Nuclear Regulation Authority studied why the No.1 reactor lost backup power and concluded on Wednesday in a report that the tsunami was the main cause, based on data about temperature, pressure and other parameters. Those data were stable immediately after the earthquake hit at 2:46 p.m., suggestingthe plant didn’t suffer critical damage

until the arrival of the tsunami some 45 minutes later.

People in the area worst affected have a slightly higher risk of developing certain cancers. The World Health Organization (WHO) released a report that estimates an increase in risk for specific cancers for certain subsets of the population inside the Fukushima Prefecture. A 2013 WHO report predicts that for populations living in the most affected areas there is a 70% higher risk of developing thyroid cancer for girls exposed as infants a 7% higher risk of leukemia in males exposed as infants, a 6% higher risk of breast cancer in females exposed as infants and a 4% higher risk, overall, of developing solid cancers for females.

THE GOVERNMENT’S REACTION-The Japanese reaction occurred after the Fukushima Daiichi nuclear disaster, following the 2011 Tōhoku earthquake and tsunami. A nuclear emergency was declared by the government of Japan on 11 March. Later Prime Minister Naoto Aniseed instructions that people within a 20 km (12 mi) zone around the Fukushima Daiichi nuclear plant must leave, and urged that those living between 20 km and 30 km from the site to stay indoors. The latter groups were also urged to evacuate on 25 March.Japanese authorities have admitted that lax standards and poor oversight contributed to the nuclear disaster. They have come under fire for their handling of the emergency, and have engaged in a pattern of withholding damaging information and denying facts of the accident.Authorities apparently wanted to "limit the size of costly and disruptive evacuations in land-scarce Japan and to avoid public questioning of the politically powerful nuclear industry". There has been public anger about an "official campaign to play down the scope of the accident and the potential health risks". The accident is the second biggest nuclear accident after the Chernobyl disaster, but more complex as all reactors are involved.

Japan towns, villages, and cities around the Daiichi nuclear plant. The 20km and 30km areas had evacuation and sheltering orders, and additional administrative districts that had an evacuation order are highlighted.

How can radioactive pollution be prevented?On one hand, the peaceful uses of radioactive materials are so wide and effective that modern civilization cannot go without them, and on the other hand, there is no cure for radiation damage. However, the only option against nuclear hazards is to check and prevent radioactive pollution by taking the following measures and precautions.

1.safety measures should be enforced strictly;2.leakages from nuclear reactors, careless handling, transport and use of radioactive fuels, 3.fission products and radioactive isotopes have to be totally stopped;4.there should be regular monitoring and quantitative analysis through frequent sampling in the risk areas;4.waste disposal must be careful, efficient and effective;5.appropriate steps should be taken against occupational exposure;6.safety measures should be strengthened against nuclear accidents; and7.preventive measures should be followed so that background radiation levels do not exceed the permissible limits.