On April 26, 1986, operators of the Chernobyl nuclear power plant, in Ukraine, failed to carry out tests in one of the reactors, causing an explosion of Uranium-235, an element of high radioactive power. The balance was 30 deaths and 1,800 notifications of thyroid cancer.
Goiania, 1987. Capsule with Cesium Chloride 137 was exposed after garbage collectors dismantled an abandoned X-ray machine. The biggest radiological accident in Brazil left four people dead immediately and had serious consequences for the survivors.
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The city of Fukushima, Japan, was the most recent victim of nuclear accidents. In 2011, an earthquake measuring 8.9 on the Richter scale caused severe damage to the nuclear power plant located northeast of the island, causing three explosions.
The three cases above show the severity of excessive exposure to radioactivity. Although, in small amounts, radioactive elements have important uses, high levels of radiation can lead to death.
Next, we will deal with the subject of the effects of radioactivity on the human body in greater detail, from its use in medicine to serious consequences from exposure.
A radiation is the propagation of any type of energy by means of waves. This also applies to light and heat. It turns out that some chemical elements have unstable properties, that is, there is no balance between the particles that form their nucleus.
Consequently, gamma-type rays are released with the ability to penetrate matter in a deep way. What about ionizing radiation? This is the type of radiation that harms living organisms and is beyond the visible spectrum.
It is the type of radiation that occurs when there is a nuclear fission. Its electromagnetic waves have a very high frequency capable of altering the charge arrangement of an atom, changing its way of interacting with others.
Thus, the bonds that keep the molecules together inside the cell occur. As consequences, internal and external burns can arise, as well as genetic mutations and irreversible damage to cells.
Sievert (Sv) is the unit by which the biological effects of radiation are measured. Already gray (Gy) is the measurement of physical effects. The two units are articulated as follows: the radiation dose in human tissue (Sv) is found by multiplying the dose in Gy.
This multiplication is done by factors that depend on the part of the body affected, the type of radiation, intensity and time of exposure.
In a previous section, we commented that the ionizing radiation causes burns and cell mutations. The former happen because the heat emitted is so strong that it causes greater damage than that caused by prolonged exposure to the sun.
Mutations, in turn, happen by the following. Radioactive particles carry a high kinetic charge and therefore move quickly. When they reach body cells, they cause cell ionization.
That is, the cells are transformed into ions and then remove the electrons (negative particles), weakening the bonds. Then come the genetic mutations that can cause problems in the gestation of the fetus and even in later generations.
The most affected cells are those with a high proliferation rate, such as medullary and reproductive cells.
The effects of radiation can be divided into two types – acute or chronic. These may manifest years after indirect but significant exposure. The highs, in turn, are immediate and appear in cases of direct or excessive exposure.
Burns, one of the effects we have already mentioned, are typical examples of acute damage that also include disruption of platelets (linked to blood clotting) and a drop in immune resistance.
In addition to the acute effects, such as burns, there is concern about chronic damage, such as genetic mutations. One of the most serious is cancer. Radioactivity accelerates cell functioning, causing them to multiply.
Uncontrolled growth causes tumors. However, they can appear up to ten years from exposure. The time until the first symptoms appear is called the “latent period”. Cases of leukemia, however, can reduce the time by two years.
Nuclear accidents, such as those mentioned at the beginning of this article, can cause contamination of the environment due to the leakage of radioactive components. Therefore, the risk of this material entering the human food chain increases.
Contamination, then, can happen by ingestion of water, meat or vegetables exposed to excess radiation. This is where chronic damage linked to cancer, thyroid problems and sterility can arise.
The sad thing is that the effects of radiation can extend for years, that is, reach generations. This is the case of direct victims of Cesium 137, whose children have serious problems as a result of parental exposure to radioactive material.
Damage according to radiation levels
Weakness, nausea and vomiting.
Depression of spinal function. Red and white blood cells are destroyed by radioactive particles.
A radiation reaches the gastrointestinal system, causing diarrhea, vomiting and bleeding.
Radiation causes acute respiratory failure.
Radiation leads the person to coma and even death by destroying cells in the central nervous system.
X-ray exams do not cause cancer due to the low dose of radiation. Therefore, they follow safe procedures such as X-rays, tomography and mammography. However, if exposure accumulates to 10 millisieverts, the risk of the disease increases.
Radiotherapy is the technique used to fight cancer. In it, the patient is subjected to controlled doses of radiation, eradicating the malignant cells. Its effects are beneficial because a high load is divided into several sessions applied to specific parts.
A patient with lung cancer, for example, is subjected to an average dose of 50,000 millisieverts. If I received it all at once, I wouldn't resist, but the applications are made in 18 to 20 sessions and only the area with the tumor is reached, saving the neighboring ones.
Still, some symptoms are felt, such as nausea. Furthermore, if the dose is increased, other tissues begin to be affected, especially the medulla, so that the patient becomes anemic and unable to defend himself against other diseases.
No, as mentioned earlier, even small doses can be very beneficial. In Medicine, radioactivity is applied in the treatment of cancerous tumors, through radiotherapy.
In Industry, radioactivity is used to obtain nuclear energy. Another applicable use is in Science. With radioactivity, it is possible to promote the study of the molecular and atomic organization of other elements.
