RADIOACTIVE CONTAMINATION: TYPES, CAUSES, CONSEQUENCES - ENVIRONMENT - 2025

The radioactive contamination is defined as the incorporation of radioactive unwanted elements in the environment. This can be natural (radioisotopes present in the environment) or artificial (radioactive elements produced by humans).

Among the causes of radioactive contamination are nuclear tests that are carried out for military purposes. These can generate radioactive rains that travel several kilometers through the air.

Nuclear explotion. Source: Photo courtesy of National Nuclear Security Administration / Nevada Site Office

Accidents in nuclear power plants are another of the main causes of radioactive contamination. Some sources of contamination are uranium mines, medical activities, and radon production.

This type of environmental pollution has serious consequences for the environment and human beings. The trophic chains of the ecosystems are affected and people can have serious health problems that cause their death.

The main solution for radioactive contamination is prevention; Safety protocols must be in place for the handling and storage of radioactive waste, as well as the necessary equipment.

Among the places with great problems of radioactive contamination we have Hiroshima and Nagasaki (1945), Fukushima (2011) and Chernobyl in Ukraine (1986). In all cases, the effects on the health of exposed persons have been serious and have caused many deaths.

Types of radiation

Radioactivity is the phenomenon by which some bodies emit energy in the form of particles (corpuscular radiation) or electromagnetic waves. This is produced by so-called radioisotopes.

Radioisotopes are atoms of the same element that have an unstable nucleus, and tend to disintegrate until reaching a stable structure. When they disintegrate, atoms emit energy and particles that are radioactive.

Radioactive radiation is also called ionizing, since it can cause ionization (loss of electrons) of atoms and molecules. These radiations can be of three types:

Alpha radiation

Particles are emitted from ionized helium nuclei that can travel very short distances. The penetration capacity of these particles is small, so they can be stopped by a sheet of paper.

Beta radiation

Electrons that have high energy are emitted, due to the decay of protons and neutrons. This type of radiation is capable of traveling several meters and can be stopped by glass, aluminum or wood plates.

Gamma radiation

It is a type of electromagnetic radiation with a high energy, which originates from an atomic nucleus. The nucleus goes from an excited state to a lower energy state and electromagnetic radiation is released.

Gamma radiation has a high penetrating power and can travel hundreds of meters. To stop it, plates of several centimeters of lead or up to 1 meter of concrete are required.

Types of radioactive contamination

Radioactive contamination can be defined as the incorporation of unwanted radioactive elements into the environment. Radioisotopes can be present in water, air, land, or living things.

Depending on the origin of radioactivity, radioactive contamination is of two types:

natural

This type of contamination comes from radioactive elements that occur in nature. Natural radioactivity originates from cosmic rays or from the earth's crust.

Cosmic radiation is made up of high-energy particles that come from outer space. These particles are produced when supernova explosions occur, in stars, and in the Sun.

When radioactive elements reach Earth they are deflected by the electromagnetic field of the planet. However, at the poles the protection is not very efficient and they can enter the atmosphere.

Another source of natural radioactivity is the radioisotopes present in the earth's crust. These radioactive elements are responsible for maintaining the internal heat of the planet.

The main radioactive elements in the Earth's mantle are uranium, thorium and potassium. The Earth has lost elements with short radioactive periods, but others have a life of billions of years. Among the latter, uranium ₂₃₅, uranium ₂₃₈, thorium ₂₃₂ and potassium _{40 stand out}.

Uranium ₂₃₅, uranium ₂₃₈ and thorium ₂₃₂ form three radioactive nuclei present in the dust that creates stars. These radioactive groups when disintegrating give rise to other elements with shorter half-lives.

Radium is formed from the decay of uranium ₂₃₈ and radon (a gaseous radioactive element) is formed from this. Radon is the main source of natural radioactive contamination.

Artificial

This pollution is produced by human activities, such as medicine, mining, industry, nuclear testing, and power generation.

During the year 1895, the German physicist Roëntgen accidentally discovered artificial radiation. The researcher found that the X-rays were electromagnetic waves that originated from the collision of electrons inside a vacuum tube.

Artificial radioisotopes are produced in the laboratory by the occurrence of nuclear reactions. In 1919, the first artificial radioactive isotope was produced from hydrogen.

Artificial radioactive isotopes are produced from neutron bombardment of different atoms. These, by penetrating the nuclei, manage to destabilize them and charge them with energy.

Artificial radioactivity has numerous applications in different fields such as medicine, industrial and military activities. In many cases, these radioactive elements are mistakenly released into the environment causing serious pollution problems.

Causes

Radioactive contamination can originate from different sources, generally due to the wrong handling of radioactive elements. Some of the most common causes are mentioned below.

Nuclear tests

Nuclear plant in Pennsylvania, United States. Source: See page for author Centers for Disease Control and Prevention's Public Health

It refers to the detonation of different experimental nuclear weapons, mainly for the development of military weapons. Nuclear explosions have also been carried out in order to dig wells, extract fuel or build some infrastructure.

Nuclear tests can be atmospheric (within the Earth's atmosphere), stratospheric (outside the planet's atmosphere), underwater, and underground. The atmospheric ones are the most polluting, since they produce a large amount of radioactive rain that is dispersed over several kilometers.

Radioactive particles can contaminate water sources and reach the ground. This radioactivity can reach different trophic levels through food chains and affect crops and thus reach humans.

One of the main forms of indirect radioactive contamination is through milk, which is why it can affect children.

Since 1945, some 2,000 nuclear tests have been carried out worldwide. In the particular case of South America, radioactive fallout has mainly affected Peru and Chile.

Nuclear power generators (nuclear reactors)

Many countries currently use nuclear reactors as a source of energy. These reactors produce controlled nuclear chain reactions, usually by nuclear fission (breaking of an atomic nucleus).

Pollution occurs mainly by leakage of radioactive elements from nuclear power plants. Since the mid-1940s, there have been environmental problems associated with nuclear power plants.

When leaks occur in nuclear reactors, these pollutants can move hundreds of kilometers through the air, causing contamination of water, land and food sources that have affected nearby communities.

Radiological accidents

They generally occur associated with industrial activities, due to improper handling of radioactive elements. In some cases, the operators do not handle the equipment properly and leaks to the environment can be generated.

Ionizing radiation can be generated causing harm to industrial workers, equipment or released into the atmosphere.

Uranium mining

Uranium is an element found in natural deposits in different areas of the planet. This material is widely used as a raw material to produce energy in nuclear power plants.

When these uranium deposits are exploited, radioactive residual elements are generated. The waste materials that are produced are released to the surface where they accumulate and can be dispersed by wind or rain.

The waste produced generates a large amount of gamma radiation, which is very harmful to living beings. Also, high levels of radon are produced and contamination of water sources at the groundwater table by leaching can occur.

Radon is the main source of contamination for workers in these mines. This radioactive gas can be easily inhaled and invade the respiratory tract, causing lung cancer.

Medical activities

Radioactive isotopes are produced in the various applications of nuclear medicine that must then be discarded. Laboratory materials and wastewater are generally contaminated with radioactive elements.

Similarly, radiotherapy equipment can generate radioactive contamination to operators as well as patients.

Radioactive materials in nature

Radioactive materials in nature (NORM) can normally be found in the environment. They generally do not produce radioactive contamination, but different human activities tend to concentrate them and they are becoming a problem.

Some sources of concentration of NORM materials are the combustion of mineral coal, petroleum-derived fuels and the production of fertilizers.

In areas where garbage and various solid wastes incinerate, accumulation of potassium ₄₀ and radon ₂₂₆ may occur. In areas where charcoal is the main fuel, these radioisotopes are also present.

Phosphate rock used as fertilizer contains high levels of uranium and thorium, while radon and lead accumulate in the oil industry.

Consequences

About the environment

Water sources can be contaminated with radioactive isotopes, affecting various aquatic ecosystems. Likewise, these polluted waters are consumed by various organisms that are affected.

When soil contamination occurs, they become impoverished, lose their fertility and cannot be used in agricultural activities. Furthermore, radioactive contamination affects food chains in ecosystems.

Thus, plants are contaminated with radioisotopes through the soil and these pass to herbivores. These animals can undergo mutations or die as a result of radioactivity.

Predators are affected by the reduced availability of food or by being contaminated by consuming animals laden with radioisotopes.

About humans

Ionizing radiation can cause lethal harm to humans. This occurs because radioactive isotopes damage the structure of the DNA that makes up cells.

Radiolysis (decomposition by radiation) occurs in cells both of DNA and of the water contained in them. This results in cell death or the occurrence of mutations.

Mutations can cause various genetic abnormalities that can lead to inherited defects or disease. Among the most common diseases are cancer, particularly of the thyroid, since it fixes iodine.

Likewise, the bone marrow can be affected, which causes different types of anemia and even leukemia. Also, the immune system can be weakened, making it more sensitive to bacterial and viral infections.

Among other consequences is infertility and the malformation of fetuses of mothers subjected to radioactivity. Children can have learning and growth problems as well as small brains.

Sometimes the damage can cause cell death, affecting tissues and organs. If vital organs are affected, death can result.

Prevention

Radioactive contamination is very difficult to control once it occurs. This is why efforts should be focused on prevention.

Radioactive waste

Radioactive waste storage. Source: D5481026

The management of radioactive waste is one of the main forms of prevention. These must be arranged following safety regulations to avoid contamination of the people who handle them.

Radioactive waste should be separated from other materials and try to reduce its volume to be more easily handled. In some cases, these wastes are treated to convert them into more manipulable solid forms.

Subsequently, radioactive waste must be placed in suitable containers to avoid contaminating the environment.

The containers are stored in isolated sites with security protocols or they can also be buried deep in the sea.

Nuclear power plants

One of the main sources of radioactive contamination are nuclear power plants. Therefore, it is recommended that they be built at least 300 km away from urban centers.

It is also important that nuclear power plant employees are adequately trained to operate equipment and avoid accidents. Likewise, it is recommended that the populations near these facilities are aware of the possible risks and ways of acting in the event of a nuclear accident.

Protection of personnel working with radioactive elements

The most effective prevention against radioactive contamination is that personnel are trained and have adequate protection. It should be possible to reduce the time of exposure of people to radioactivity.

Facilities must be properly constructed, avoiding pores and cracks where radioisotopes can accumulate. Good ventilation systems must be in place, with filters that prevent waste from leaving the environment.

Employees must have adequate protection, such as screens and protective clothing. In addition, the clothing and equipment used must be decontaminated periodically.

Treatment

There are some steps that can be taken to alleviate the symptoms of radioactive contamination. These include blood transfusions, immune system enhancement, or bone marrow transplantation.

However, these treatments are palliative as it is very difficult to remove radioactivity from the human body. However, treatments are currently being carried out with chelating molecules that can isolate radioisotopes in the body.

Chelators (non-toxic molecules) bind to radioactive isotopes to form stable complexes that can be removed from the body. Chelators have been synthesized that are capable of eliminating up to 80% of contamination.

Examples of places contaminated with radioactivity

Since nuclear energy has been used in different human activities, various accidents due to radioactivity have occurred. In order for the people affected to know the seriousness of these, a scale of nuclear accidents has been established.

The International Nuclear Accident Scale (INES) was proposed by the International Atomic Energy Organization in 1990. The INES has a scale of 1 to 7, where 7 indicates a serious accident.

Examples of more serious radioactive contamination are listed below.

Hiroshima and Nagasaki (Japan)

Nuclear bombs began to be developed in the 40s of the 20th century, based on the studies of Albert Einstein. These nuclear weapons were used by the United States during World War II.

On August 6, 1945, a uranium-enriched bomb exploded over the city of Hiroshima. This generated a heat wave of about 300,000 ° C and a large burst of gamma radiation.

Subsequently, a radioactive fallout was produced that was spread by the wind, taking the contamination further away. Approximately 100,000 people died from the explosion and 10,000 more were killed by radioactivity in the following years.

On August 9, 1945, a second nuclear bomb exploded in the city of Nagasaki. This second bomb was enriched in plutonium and was more powerful than the Hiroshima one.

In both cities, the survivors of the explosion had numerous health problems. Thus, the risk of cancer in the population increased by 44% between 1958 and 1998.

Currently there are still consequences of the radioactive contamination of these bombs. It is considered that more than 100,000 people affected by radiation live, including those who were in the womb.

In this population there are high rates of leukemia, sarcomas, carcinomas, and glaucoma. A group of children subjected to radiation in the womb, presented chromosomal aberrations.

Chernobyl (Ukraine)

It is considered one of the most serious nuclear accidents in history. It happened on April 26, 1986 at a nuclear power plant and is level 7 at INES.

Workers were conducting a test simulating a power outage and one of the reactors overheated. This caused the hydrogen explosion inside the reactor and more than 200 tons of radioactive material were thrown into the atmosphere.

During the explosion, more than 30 people died and radioactive fallout spread for several kilometers around. It is considered that more than 100,000 people died as a result of the radioactivity.

The incidence level of various types of cancer increased by 40% in affected areas of Belarus and Ukraine. One of the most common types of cancer is thyroid cancer as well as leukemia.

Conditions associated with the respiratory and digestive systems have also been observed due to exposure to radioactivity. In the case of children who were in the womb, more than 40% had immunological deficiencies.

There have also been genetic abnormalities, an increase in diseases of the reproductive and urinary system as well as premature aging.

Fukushima Daiichi (Japan)

Fukushima Nuclear Power Plant, Japan. Source: Digital Globe

This accident was the result of a magnitude 9 earthquake that struck Japan on March 11, 2011. Subsequently, a tsunami occurred that deactivated the cooling and electricity systems of three of the reactors at the Fukushima nuclear power plant.

Several explosions and fires occurred in the reactors and radiation leaks were generated. This accident was initially classified as level 4, but due to its consequences it was later raised to level 7.

Most of the radioactive contamination went to the water, mainly the sea. There are currently large storage tanks for contaminated water at this plant.

These polluted waters are considered a risk to the ecosystems of the Pacific Ocean. One of the most problematic radioisotopes is cesium, which moves easily in water and can accumulate in invertebrates.

The explosion did not cause direct radiation deaths, and levels of radioactivity exposure were lower than those of Chernobyl. However, some workers had DNA alterations within days of the accident.

Similarly, genetic alterations have been detected in some populations of animals subjected to radiation.

References

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