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The evacuation in the wake of the Chernobyl accident lasted until mid-May, starting a day and a half after the accident. Pripyat would be the first city to be evacuated, supposedly for 3 days. Immediately after the accident, the city was not contaminated since the wind was blowing in a different direction towards it, but the graphite fire that would last for days made it clear that the city would be uninhabitable. The decision to evacuate was made at 11 o’clock on the day of the accident, although it was not carried out until 2:00 p.m. on the following day, on April 27.
During the evacuation family criteria were not taken into account, so that a family could have each of the members evacuated in different areas, adding stress to the population. Approximately 49,000 people evacuated the city in 1200 buses, 36 hours after the accident. The government committee to deal with the accident did not evacuate until several days later, when they moved to the city of Chernobyl 12 miles from the plant. Later they would move to Ivankovo, 31 miles from the nuclear power plant.
The complete relocation of the evacuees was completed in September 1986. Residents were moved to Kiev and Chernigov, but even in the year 2000 there would still be 11 000 evacuated people living in temporary settlements. The evacuation policy was based on resettling the entire population living in areas with a greater or lesser degree of contamination, and according to the dose they would receive during the rest of their lives.
A total of 137 600 people were evacuated due to radioactive contamination, in addition to building more than 66 000 houses and apartments for displaced people. These people were given compensation for the accident, which was later interpreted as compensation for late health effects, and not for the evacuation. This ended up increasing stress levels of people and would justify the appearance of radiophobia.
Other parties affected by the accident were not evacuated, where today they live around 5 million people. Other thousands of people live in contaminated areas between 15 and 40 Ci / km ^ 2.
The evacuation prevented the absorption of a higher dose as a result of the accident in the plant due to the continuous escapes during 10 days, and the action of the contamination of the land. Numerous buildings and infrastructures were built for evacuees.
In the Soviet socialist republic of the Russian Federation, four classifications were designated for the evacuation of people: An exclusion zone, evacuation zone, habitable zones with the right to request resettlement and habitable zones with socioeconomic preferences: In the exclusion zone the use of forests, agriculture, production or processing of minerals are forbidden, or any means of public transport is allowed. Any economic activity is prohibited as there are pollution levels greater than 1480 kBq / m2. In the evacuation zone, whose contamination varies between 555-1480 kBq / m2, any economic activity carried out would be monitored, agriculture could be carried out based on scientific recommendations. In general, this area will be gradually rehabilitated. In the habitable zones with the right to resettlement, with a land contamination of between 185-555 kBq / m2, any economic activity without any restriction is allowed, although the state and improvement of the environment will be monitored. Finally, in the living areas with economic preferences, with a contamination of between 37 and 185 kBq / m2, economic activities can be carried out without any restriction or monitoring of any kind.
Long term actions
The sarcophagus covering the reactor that was built immediately after the accident, was only a temporary structure to last a maximum of 30 years, needing a new structure that would allow the dismantling of the destroyed reactor and that of the rest of the reactors in a safer environment. Outside this, radiation levels are not high, except in the roof, where the dose immediately after construction was 0.5 Gy / h. 9 years later it fell by a factor of 10.
After the sarcophagus was finished, built in a hurry as a temporary solution, problems appeared in this: Problems in its long-term stability and resistance, which posed a potential danger should it collapse. The supports holding the sarcophagus were the same as that of unit 4 before being destroyed, and probably the explosion and fire of the reactor caused a weakening of the structures. In the worst case, the roof of the sarcophagus would collapse. The problem was aggravated by the appearance of corrosion in the materials due to rainwater leaks, since the enclosure was not watertight. The built structure was also not made to withstand earthquakes or tornadoes.
The upper biological shield (the reactor cover) was held between two walls, and could come down. The condition of the foundations under the reactor, which would probably be damaged by the corium that passed through them, is not known. If this failed, the entire structure of the building would collapse.
Different situations have been studied that could cause a breach in the sarcophagus and the subsequent release of radioactive material in the form of suspended particles: fall of the roof, internal structures, a criticality event and the filtration of elements in groundwater. A reinforcement plan of the sarcophagus was carried out to ensure that the structure would sustain enough time, and if not, to diminish the consequences.
The rest of the reactors of the nuclear power plant remained in operation until the year 2000, when the last of them would close. Since the accident in Unit 4, all western countries put pressure on Ukraine to close the Chernobyl complex. One way would be to exert pressure through negotiations and agreements between countries, for example in 1995 the European Union and Ukraine would agree to close Chernobyl in exchange for aid to solve supply problems arising from the closure of the plant. It should be borne in mind that the closure of the station would cause a loss of jobs, adding additional stress to the region affected by the nuclear accident.
Unit 1 would close in November 1996, and its dismantling would be decided in December of the following year. Unit 2 stopped in 1991 after a fire in the turbine building. Unit 3 would stop definitively on December 15th, 2000. Units 5 and 6 were under construction on the day of the accident, but works were temporarily suspended, and then resumed for a year, to then be finally canceled one year later, in 1987.
With the sarcophagus unable to withstand in the long term and with the need to replace it, the NSC – New Safe Confinement – was built, a mobile structure that will isolate the damaged reactor from the environment in order to carry out the dismantling of the rest of the units safely. During the first phases, the old sarcophagus will be partially dismantled, to then dismantle what remains of the destroyed reactor. The dismantling is expected to be complete by the 2120s.
The fuel of the rest of the units is now stored dry in a new facility certified by the US Nuclear Regulatory Commission. Two other buildings in which the fuel will be treated and stored in containers, are already built.
Workers at the Chernobyl plant were all moved to the substitute town of Pripyat, “Slavutych”, about 18 miles from the plant. This city began to be built while the decontamination work began for the start-up of the third reactor.
Radioactive activity is measured in Becquerels (Bq) – Disintegrations per second -, while the radioactive contamination is measured in Bq / m2 or in Ci (Curies) / km2 – the activity of one gram of Radium -. It is important to bear in mind that naturally everything has a minimum radioactive activity. According to the specific case, we will talk about Bq / m3, Bq / m2 or Bq / kg. In the case of radon gas, we talk about Bq / m3.
Although we are naturally surrounded by a radioactive activity, we will talk about soil, air or mass contamination – specific radioactive activity – when we find artificially produced isotopes. As a final note, it should be noted that some of the maps of radioactive activity by Cesium take into account the deposition of this isotope as a result of atmospheric nuclear tests that were carried out. In European territory this concentration is around 2-4 kBq / m2. The limits of contamination of food according to the Codex Alimentarius -OMS and UN- define the limits in foods of not only radioactive contaminants, but of all kinds of contaminants.
Immediately after the explosion of the reactor, the complete inventory of noble gases was released from it, while the incandescent hot fuel and the graphite fire were gradually releasing the solid material. Emissions amounted to 13 EBq (Exabecquerels, 1 · 10 ^ 18), 1.8 EBq of Iodine-131, 85 PBq of Cesium 137 and 134, 10 PBq of Strontium-90 and 3 PBq of Plutonium-239. The remaining 50% correspond to the noble gases Xenon and Krypton. These emissions were changing over the days, stopping definitively on the tenth day after the explosion of the reactor.
Much of the dose received by the population came directly from contamination of Iodine-131 Iodine-134, and isotopes of Tellurium, with a disintegration period of 8 days in the case of Iodine-131 and less than a day in the other two. Iodine would be responsible for six thousand cases of thyroid cancer.
The cesium emission caused by the reactor fire contaminated practically all of Europe, except the Iberian Peninsula and part of the United Kingdom.
The emissions of Plutonium released by the accident were deposited within the exclusion zone of 18 miles around the nuclear power plant, being a very heavy isotope, the wind was not able to drag it beyond a radius of 18 miles.
The reactor’s fire lasted 10 days, with different emission periods during each of them. The first 5 days emissions decreased and then increased 5 days later. Emissions ended when the reactor penetrated the lower biological barrier and interacted with other materials under the reactor, cooling it.
In the vicinity of the plant, just after the accident, radiation levels increased in the southwest direction, as the direction in which the wind was blowing. The forest through which the radioactive cloud of the explosion passed died the next day. This forest was renamed “Red Forest”, since the radiation had stopped the chlorophyll production of the trees, turning them orange. The city of Pripyat would still take a few days to become contaminated, due to changes in wind direction. On the day of the accident, contamination was found more than 62 miles from the plant, specifically in bakeries in Kiev. The radioactive plume, guided by atmospheric conditions during the fire, caused heterogeneous contamination throughout Europe.
The contamination in the vicinity of the plant was mainly due to Strontium, different isotopes of Plutonium and Americium-141. Particles of lower density, dragged by the wind and deposited by rainwater, arrived throughout Europe. This contamination could be found to a greater or lesser extent throughout the northern hemisphere, but especially in Europe. In each of the affected countries the pollution was different, but there was a general tendency to decrease the number of contaminated miles as one moved away from the reactor, except in Austria, Norway, Finland and Sweden, where there are peaks of pollution. The contamination by Chernobyl seriously contaminated zones to 124 miles, besides a great part of Austria. The radioactive plume was detected in places as far away as North America, while in the southern hemisphere it went virtually unnoticed.
The three countries with the highest radioactive contamination were Belarus with 43 500 km2 (23% national territory), 59,300 km in Russia (1.5%) and
37 600 km in Ukraine (5%). According to the contamination of the soils, different evacuation areas were designated with their own economic and social limitations. Any place with a contamination exceeding 37,000 Bq / m2 is considered contaminated. Some areas of the 3 main affected countries were out of service for use in the primary sector. The firewood trade was regulated and 30% of the pines within the exclusion zone could not be cut. Soil pollution is so high that fires and storms can put the pollution in suspension, allowing it to be moved to other areas. It happened in 1987 and 1992.
As for the Pripyat river, the greatest peak of contamination had it just at the time of the accident because of Iodine-131. The water samples from the following days indicated that it was slightly contaminated. Later years, water samples indicated that they were somewhat above the limits for human consumption (2 Bq / l). After the accident there were concerns about the contamination of aquifers, so alternative measures were prepared for water consumption, although finally it was not necessary to apply them.
To reduce the consequences of radioactive contamination from the accident, measures were taken at the local level according to the degree of contamination of that area. In the most affected sites, a decontamination of public buildings and streets was carried out to avoid dust. In areas with less affectation, the measures were more routine and simpler, such as washing the fruit and vegetables before consuming it.
After the first months after the accident, the only thing that would decrease the levels of radioactivity would be the very law of physics, following the decay period of Cesium-137.
The equivalent doses absorbed by an organism are calculated using the multiples of the Sievert (Sv), since a Sv is a very high dose for the use that is given to it. So, the miliSievert (mSv) and microSievert (uSv) are used. There is another unit of calculation for the dose absorbed by an organism called Gray, but it does not take into account the effects that this dose could have on the organism. Therefore, the absorbed dose (Gy) of the equivalent dose (Sv) is distinguished.
We are naturally surrounded by radioactive sources that provide us with an equivalent annual dose of approximately 2.4 mSv / year. Depending on the terrain or surroundings we are in, the dose will change from one value to another. The natural values vary from 1 to 10 mSv / year, although there are areas where there are more than 50 mSv / year. One of the areas with the highest dose are the states of Kerala and Madras of India, with 15 mSv / year of gamma radiation, in addition to the contribution of Radon. Other places with doses of up to 40 mSv / year are found in Brazil and Sudan. A Brazilian beach has the annual natural dose record with 800 mSv / year, but nobody lives near that area. In Europe, Iran and India there are several places with doses of more than 100 mSv per year, with peaks of up to 260 mSv per year without this having shown an increase in the cancer rate. The value of 100 mSv / year is the theoretical value taken by the UNSCEAR where the risk of cancer begins to increase little by little. Theoretical because it has not been demonstrated experimentally. Starting from 250 mSv / year, a statistical epidemiology begins to be seen. As an example, a computed tomography of the pelvis and abdomen provides a dose of 10 mSv. A dose of 400 mSv absorbed within a few hours may cause acute radiation syndrome. The effects are greater at higher doses and less time.
During the Chernobyl accident, the doses received by the population vary according to time: During the first days most of the received dose was caused by Tellurium-132, Iodine-131, short-lived fission products and noble gases. After the days, only Cesium, Strontium and Iodine would be significant. Finally, after only a few years, Cesium-137 would become the most significant. Other isotopes such as the Plutonium and Strontium will only be considered in the vicinity of the plant.
Doses received by population vary according to geographical location and activity of the people, therefore, the dose is divided into four large groups: workers of the plant and liquidators, evacuated population, population in the USSR and population outside the USSR.
Workers of the plant, firemen and liquidators
The number of workers, firemen and others who provided their services during the first moments of the accident, add up to a few hundred people, with 400 workers at the plant. These people were exposed to gamma and beta radiation from the radioactive cloud, to external contamination (and inhalation), contamination of their clothes and fuel fragments scattered from the reactor. 41 of these people received general doses throughout the body from 1 to 2 Sv, 50 between 2 and 4 Sv, 22 between 4 and 6 Sv, and 21 between 6 and 21 Sv (fatal). In addition, the specific doses to the thyroid gland varied between 0.1 and 20 Gy.
The liquidators, who number 600 000 people targeted to the lists that recognize them as such, were responsible for the tasks of construction of the sarcophagus and decontamination of the most affected areas. It should be noted that the actual number of liquidators can be 400 000, significantly less than 600 000, since many of them signed up for the lists because of the economic advantages they had when considered as such.
Until June 1986, sufficient measures were not established to measure the dose received by the liquidators, therefore the doses received during the first weeks were based on geographical estimates whose dose was known. Data from the three national registries of Russia, Belarus and Ukraine show that the median doses received by the liquidators were decreasing year by year: 170 mSv, 130 mSv, 30 mSv and 15 mSv annually in 1986, 1987, 1988 and 1989 respectively.
The evacuation of Pripyat was made after the city was affected by the accident due to a change in the direction of the wind. In this way, and according to 30,000 questionnaires made to the evacuees, the received dose can be reconstructed. The mean effective dose of these people (49 000) was 17 mSv, with individual values ranging from 0.1 to 380 mSv. The estimates are in line with other estimates. The main source of the doses received were I-131, Te-132 and Cs-137. The first two by ingestion or inhalation, while the last by deposition. A total of 5000 measurements were made in thyroid glands of the inhabitants of Pripyat that allowed to reconstruct the doses received in the gland. The whole-body doses of the evacuees were due to the external exposure of Te-132, I-131, Cs-134 and Cs-137, in addition to short-lived radioisotopes suspended in air. According to measurements and questionnaires, the dose of 90 000 people was reconstructed.
People living in contaminated areas
Polluted areas with more than 37 kBq / m2 of Cs-137 are considered affected by the accident. This is because there is a contamination background product of atomic bomb testing, between 2 and 4 kBq / m2. In areas with more than 555 kBq / m2 of Cs-137, activities have been carried out to limit the dose to 5 mSv per year (2 times the average natural world background). Due to emigration, the number of people in these areas has decreased from 273 000 to 193 000 from 1986 to 1995.
About doses to the thyroid gland, 150 000, 60 000 and several thousand measurements were made in Ukraine, the Russian Federation and Belarus respectively during May and June 1986. For the population living in Belarus, the average dose to the gland Thyroid is 0.9 to 1 Gy for children aged 0 to 7 years. 0.3 Gy for the rest of the population. The average dose to the thyroid for the population of the three socialist republics affected is 7 mGy. 1 Gy for the most exposed children. It is important to note that doses have been higher in rural areas than in urban areas. In some villages of the Russian Federation the average dose exceeded Gy, and some individual doses exceeded 10 Gy. As for thyroid doses “in utero” there is very limited information. In a study of 250 children born between 86 and 87 in Belarus, the doses were estimated at 2.4 Gy at most. Of the 250 children exposed, 135 were exposed to less than 0.3 Gy, 95 to 0.3-1 Gy and the remaining 20 with doses of more than 1 Gy. Questionnaires on food consumption showed that the highest source of dose was contaminated milk. In some cases, the consumption of vegetables was what ended up producing the greatest contribution to the exhibition.
The doses received in the whole body were conditioned by two main factors: Exposure to external irradiation and ingestion of contaminated food. The first is directly related to the activity per unit area. The dose received for the consumption of contaminated food varies according to consumption habits and / or precautions taken. In rural contaminated areas food produced locally was consumed. During the first years of the accident, Cesium was the main contributor to the internal dose for ingestion of food, mainly milk, whose contamination decreased over time. Years later, the largest contributor became mushrooms, due to economic changes in the area, which caused people to increase their consumption.
The lifetime dose received by the population living in contaminated areas is between 42 to 88 uSv per kBq / m2 of contamination with Cs137. 60% of this dose absorbed the first 10 years. This means that they will receive a total dose of 48 mSv. Of these, 30 mSv were received for the first 10 years, which with an exponential decrease in dose received 10 mSv during the first year (4 times above the natural world average).
The dose received by 5 200 000 people during the first 10 years after the accident – in which 60% of the dose is received for life – is 24 200 Sv · person, that is, 4.65 mSv per person. The internal doses were 5500 Sv · person, 5000 Sv · person and 7900 Sv · person in Belarus, Russian Federation and Ukraine respectively. The sum of internal and external doses indicates a collective dose estimated in the population of contaminated areas, excluding thyroid doses of (see attached table):
Population outside the Soviet Union
Although the most affected countries were the socialist republics of Belarus, Ukraine and Russia, the most volatile radionuclides (Iodine-131 and Cesium-137) were detected in most countries of the northern hemisphere. As a general rule, doses tended to decrease as the distance to the reactor increased, except in specific cases where rainwater deposited radionuclides. During the first weeks of the accident, Iodine-131 was the main responsible for doses through consumption of milk. Doses in children were from 1 to 20 mGy in Europe, from 0.1 to 5 mGy in Asia and 0.1 mGy in North America. Doses in adults was 5 times lower than that received by children in different areas of the world.
Time after, Cesium 134 and 137 would be predominant: The dose in all the equivalent body received during the first year would be 0.05 to 0.5 mGy in Europe, 0.005 to 0.1 mGy in Asia and 0.001 mGy in North America.
Impact on physical health
The physical health impacts of exposure to ionizing radiation vary according to two main variables: Time and dose. The higher the dose and the shorter the time, the greater the effects.
There are different models for estimating the health consequences of exposure to ionizing radiation, the most used in radiological protection but extremely conservative is the LNT – Linear No Threshold -. This model points out that any threshold of radioactivity causes an increase in cancer rates and health consequences associated with the dose. It is not used in the most modern studies of epidemiology because of the inaccuracy involved in using it. In studies of epidemiology and effects of radioactivity, the UNSCEAR model is used, which classifies the doses as very low when they are less than 10 mGy, low when they are less than 100 mGy and high when they exceed 1000 mGy. Scientific evidence shows that for doses below 100 mSv per year, no health damage has been demonstrated, although the limits in areas of nuclear accidents or personnel of nuclear power plants have a much lower annual dose limited by following the LNT.
No positive effects have been recognized in doses, but it is an object of study. No immediate or long-term effects have been recognized in doses lower than 100 mSv per year. Between 100 and 250 mSv there is no scientific consensus for the effects of these doses, since the possible cancers produced by these doses would be camouflaged in the statistics along with cancers produced by other causes such as smoking.
From an annual minimum of 250 mSv there is an epidemiological increase in the cancer rate of the exposed population. The probability grows linearly with the dose. The natural fund in Ramsar, Iran, has this value, but no consequences have been identified. A dose of 400 mSv in the short term can cause the first symptoms of acute radiation syndrome. An exposure at the same time threshold at 1 Sv increases the probability of suffering a fatal cancer by 5%. 5 Sv short-term would kill 50% of people exposed within a period of one month. A dose of 6 Sv is considered fatal for the same period of irradiation.
The effects of short-term radiation exposure are the so-called deterministic effects, while the long-term effects are the so-called stochastic effects. Most effects of the Chernobyl accident were deterministic.
Two people died directly from the Hydrogen explosion in the reactor building. One died from the explosion, while the other died from a heart attack. A total of 237 people was hospitalized, 134 of them with acute irradiation syndrome, who received doses of between 2 and 16 Gy. Of them, 28 turned out to be fatal. 21 of these people were exposed to doses of 6 to 16 Gy and only one survived.
Acute irradiation syndrome occurs first with dizziness, nausea, vomiting, headache, diarrhea, fever, burns, internal bleeding, drop in the number of white and red blood cells as well as nervous system failure. This syndrome is classified into 4 levels of severity and absorbed dose: Light, moderate, severe and finally very severe syndrome.
People hospitalized with ARS – Acute Radiation Syndrome – were distinguished by their skin burns due to Beta radiation. Their doses contributed to failures in his bone marrow, which in 13 patients was transplanted as it stopped working. However, all died except one. Finally, it was concluded that even at high doses the marrow could recover on its own. Another 42 patients suffered inflammation in the respiratory tract and glands within a week of being hospitalized. These inflammations would cause breathing problems because of their location. Diarrhea was observed in 10 patients hospitalized with ARS after 4 days of exposure. This suggested a dose of gamma rays of more than 10 Gy. Not one survived, while 7 other patients received a lower dose and all survived.
In 7 patients with ARS of grades III and IV, pulmonary reactions accompanied by respiratory failure were observed during the first 2-3 days. All of them would end up dying between 2 and 4 weeks after the accident. 24 days after the accident, 19 patients (65% of the total who would die) died. Another 6 would do it between 25 and 48 days after the exhibition. The cause of death of the 28 patients is in the table attached.
Thermal and radiological burns were treated equally, but the treatment of the gastrointestinal syndrome was very difficult, since the damage that caused the exposure destroyed the mucous membranes and natural lubricants, which would cause inflammations.
The organizational aspects of treating patients presented problems: intensive treatment had to be carried out 24 hours a day, new techniques were taught to the staff and a large number of samples had to be examined. Radiation burns were found in 56 patients. The cataracts and ulceration that appeared later would be the most important causes of disability, among the survivors of acute radiation syndrome.
Patients with grades III and IV had a drop in their immune systems. Partial recovery would take weeks to months, while full recovery would take years. A total of 28 people died as a result of the accident during the first 3 months. 19 more would do so between 1987 and 1998 for causes not necessarily related to radioactive exposure.
The long-term consequences among survivors of ARS of grades III and IV were several: hematopoietic normalization – production of red blood cells – did not normalize until several months later. Cataracts and ulceration were the main health problems of the survivors of the syndrome, which would later be classified as invalid. The majority of survivors would also have disorders in their sexual functions, although the 14 children who were born during the first 5 years of the accident did not have any kind of problem. The most notable sequels are skin damage caused by radiological burns and cataracts.
Due to the absence of preventive treatment with iodine prophylaxis for the youngest after the Chernobyl accident, an increase in the rate of thyroid cancer was predicted 5 years after the accident, since it has a latency period of 5 years. In 1991 an increase in the cancer rate was expected in young people under 25 years of age. These cases of cancer were classified among people under 10 or 18 years of age.
There have been 4837 reported cases of cancer between 1986 and 2002. Of these, 15 have turned out to be fatal due to a lack of access to the medical care required. It is expected that cases will continue to be added up to approximately 6000. In Europe there have been no increases in thyroid cancer.
Leukemia is the disease of greatest interest due to the sensitivity it has to be caused by ionizing radiation, and the short latency period between exposure and the onset of cancer. The studies focus on adults who survived the acute radiation syndrome, however, after 5 to 15 years of exposure, the risk starts to fall, so then a cancer of the leukemia type does not have to be related to the exposition. 2 years after the accident, 46 cases of leukemia were recorded in the 3 countries most affected by the accident. However, they were not above normal neither in Russia nor Belarus. In Ukraine there was an observed increase, but this is probably reflected by the incorporation of a surveillance program, since until then there was no cancer registry system in the country. In a study by Ivanov et al, a high risk of suffering from leukemia among the liquidators of the Russian Federation was found, but these studies have been criticized for using base cases of leukemia not related to radiation. The foregoing, added to the follow-up in the health of liquidators, the surveillance programs and the reduction of health resources to study the general population, were the most predominant factors in the results. Several studies on the health of the liquidators (Cardis et al, Shantyr et al, Osechinsky et al, Buzunov et al, Bebeshko et al) have not shown evidence of an increase in the rate of cancer due to leukemia among them. Page 56 of the PDF “Annex. Exposures and Effects of the Accident Chernobyl ” that the UNSCEAR has, gives the list of studies on leukemia caused by the Chernobyl accident, together with some conclusions. Neither has evidence been found that the cases of leukemia among liquidators or people living in contaminated areas have been caused by exposure to radiation.
There is evidence of a higher incidence of cataracts in survivors of acute irradiation syndrome, appearing at doses less than 1 Gy. The minimum dose at which they can begin to appear is 150 mSv.
A strong exposure to the radiation of the heart and brain can lead to an increase in the associated health problems, although there is little solid evidence that shows effects in incidence or mortality given the low doses received. The cases observed correspond to people who have accumulated a dose greater than 150 mSv in less than 6 weeks, but such a study did not take into account other adjustment factors such as obesity, alcoholic habits or smoking habits.
Impact on psychological health
One of the biggest long-term effects of the Chernobyl accident is the degradation of the social structure in the affected territories. This has contributed to a decline in people’s living standards due to the accident. These effects have not been caused by radiation, but by the psychological stress that has persisted after the accident. The severity of these effects is accentuated by distrust of official bodies, especially those of the nuclear industry. The lack of knowledge and information about the effects of ionizing radiation from the general public have only worsened the situation: The impression of being surrounded by a contaminant that is not understood, can’t be seen, can’t be avoided and it can’t be touch, adds impotence.
This seed of distrust was sown when happened something that was told to people it could never happen: A nuclear accident. In addition, the affected population has the perception that not only their health is at risk, but so are their descendants. These psychological effects have been widely studied, and the symptoms found following the events and conditions after the accident are: Headaches, depressions, sleep disorders and emotional imbalances.
It is concluded that the Chernobyl accident has caused a long-term impact on the mental health of people. In any case, no effect is directly related to ionizing radiation. Other circumstances beyond the accident that have increased levels of stress and psychological consequences, are the financial compensation that was launched in Ukraine in 1991. These compensations ended up exaggerating the fears of the people who received them, making them believe that they had fallen in the category of victims (from Chernobyl).
At the same time, the native people of the places where they moved some people evacuated or compensated, saw these people as some who “injected into society without prior consultation.” Different surveys revealed a feeling of anxiety in all sectors of the population, but it was especially strong among those who were evacuated. They were afraid of what the future would bring to them and their offspring. To this must be added the feeling of lack of control of their own destiny. It is important to note that people who returned illegally to their homes in the most polluted areas, seemed to suffer less stress and anxiety, even having worse living conditions.
Another factor that would increase the psychological impact would be “vegetative dystonia”. The diagnosis is characterized by having imprecise symptoms and without precise diagnostic tests.
In Europe, the psychological effects of the accident were minimal, conceived more as social reactions. While in the contaminated territories of the USSR many people were convinced that they had diseases caused by radiation, in the rest of the world news of the accident reinforced the anti-nuclear perspective. An example was the demonstration on June 7, 1986 in the German federal republic. In France, despite the fact that support for nuclear energy decreased, 63% of the population considered that their nuclear power plants operated efficiently and safely.
In Sweden, the percentage of people who had a bad perception of nuclear energy went from 25% to 47% before and after the Chernobyl accident, respectively. Generally, in Europe a feeling of distrust towards the information yielded by the USSR expanded, in addition to a total exaggeration of the effects of the radioactivity, reason why the population carried out totally extremist actions with total lack of justification: Do not buy food that could be contaminated, postpone or even cancel trips, and even induced abortions would be the measures that the population would take before the fear of radioactivity.
It can be summarized that the effects on anxiety and stress in individuals were minimal compared with the collective perception and response, which had a significant social and economic impact in Europe.
Consequences in flora and fauna
Immediately after the accident, the fauna and flora around the nuclear power plant received doses of radiation that ended up causing effects on plants and animals. The most famous example is the Red Forest.
The effects produced on fauna and flora as a result of the Chernobyl accident can be classified into three parts according to various periods of time: the first 20 days, the summer and autumn of 1986 and finally a third period of time following irradiation by Cesium-137.
The first 20 days were important since most of the total doses received by plants and animals were concentrated, the great majority of them, acute doses caused by the isotopes with a shorter life.
During the second period of time, that is, from summer to autumn of 1986, the radioisotopes released by the accident migrated to different parts of the environment through different processes. The doses at the surface of the soil were 10% of the initial values.
During the third phase, which continues to this day, the dose following Cesium-137 is considered, since it is the only one that has long-term importance as it is the main source of external radiation at ground level.
Within the 30-kilometer exclusion zone around the nuclear power plant, contamination and dosage were sufficient to cause sterility and reduced productivity of some species. Both effects, very short term. The doses reached 300 mGy / d. The most notable effects are anomalies in the production of wheat between 1986-1987 by 40%. In the vicinity of the plant, at a 1 mile distance pine forest received a dose of 80 Gy, being one of the plants most sensitive to radiation with a minimum of 20 Gy / d to cause mortality. The trees reddened and this place was baptized as “Red Forest”. At lower doses, the trees could produce deformed branches and spontaneous growths of these.
After the accident, between 60 and 90% of the particles were deposited in the forest, which were then transported to the ground by rainwater. This would increase radiation levels at ground level, causing a decrease in invertebrates. A year later, the number of insects gradually returned to normal thanks to the reproduction and migration of insects from other less polluted areas. The doses received by these insects coincide with those doses at the laboratory level to sterilize insects for population control, of around 30 Gy.
On farms, the doses of some animals were higher than in others. Cows need to eat 75 kilograms of grass daily, grass that was contaminated by Iodine and Cesium. During the evacuation as a result of the accident, several animals were left behind for 2 to 4 months after the accident in the most contaminated areas. In the fall of 1986, some died, while others, for example, showed poor immune responses. The offspring of the cows exposed to more contamination, had a reduced weight, smaller daily weight increases and signs of dwarfism. The offspring was normalized in the spring of 1989.
Autopsies were carried out on wild and domestic animals that remained within a 10-kilometer radius of the reactor four months after the accident, among other tests on birds and chickens. In aquatic animals, it should be noted that the fish in the artificial lake from which the Chernobyl reactors were cooled were exposed to doses of 7-8 Gy until 1988, when they reached sexual maturity.
An increase in the level of mutations was evident in 1987: Unusual growths of tree branches, increases in the number of clusters, color and abnormal shapes of leaves and flowers and development of “witch’s disease” in pines. Mutations in flies living in the most contaminated areas, with exposures at 2 mGy / d, increased during the 1986-1987 period. The next two years, the mutation frequencies returned to their normal levels.
Of 122 wild mice captured, 2 did not produce offspring assuming they were sterile.
The exclusion zone of Chernobyl has thus become an area with a high population of bears, roe deer, red deer, moose, wolves, hares, beavers and foxes. In addition, the Chernobyl area has become a breeding area for white-tailed eagles. The acute doses product of the accident affected the balance of the ecosystem killing sensible organisms, altering the reproduction, destroying some resources (pines), etcetera.
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