Why talk about Chernobyl but not about Fukushima

Radioactivity: Consequences of Reactor Accidents - Facts and Guesses

UN Commission publishes results on the effects of the Chernobyl meltdown in 1986 on humans and the environment. However, numerous critics consider these numbers to be embellished.

The news from Japan about the state of the reactor facility in Fukushima has been rolling in for weeks. Whatever the situation, when this edition of Deutsches Ärzteblatt is printed, it is undisputed that people and the environment around the reactor have been and will be radioactively contaminated. What risk the "brave" directly on the radiation front, but also the population in the vicinity are actually exposed to, cannot currently be estimated - even if the President of the Society for Radiation Protection, Dr. Sebastian Pflugbeil says: "We are in the Chernobyl League."

Chernobyl 1986: The concrete cover of the reactor block was blown off by several explosions, leaving the nuclear reactor open and blowing large amounts of radioactive material into the environment. Photo: Keystone

The UN study has been continuously updated since 2001

In view of concerns about possible damage to the health of those affected, a report by the UN commission UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation) on the consequences of the reactor accident in Chernobyl is gaining attention. The study, which has been ongoing since 2001, is updated at regular intervals. The 178-page analysis that is now available is to be presented at the central memorial conference in Kiev on April 26th, exactly 25 years after the "worst-case scenario". The new report has been greatly expanded, said Malcolm Crick, Secretary General of UNSCEAR on March 14th in Vienna, where the key data of the report were presented. It now includes the data of more than 500,000 workers who were exposed to comparatively high doses of radioactive radiation during and after the accident. Epidemiological data on the radioactive contamination of the thyroid gland of around 100 million people were also taken into account.

As a reminder: the Chernobyl reactor accident had contaminated an area of ​​150,000 square kilometers in Belarus, Ukraine and Russia - at that time the home of five million people - with radionuclides. More than 330,000 people who lived near the reactor had to be evacuated. In addition, another 45,000 square kilometers of land in Europe was exposed to radiation from iodine-131, cesium-134 and cesium-137, albeit with different levels of intensity.

"Radionuclides from the Chernobyl release were measurable in all countries in the northern hemisphere," says the UN report. The total amount of radiation generated by the atomic nucleus decay was more than 2 × 1018 Becquerel (1 Becquerel corresponds to the activity of a radioactive substance per second) distributed in the environment.

Mortality and morbidity data

How dangerous are these radionuclides for human health then and now? Can the Chernobyl data provide information on the long-term effects of low radiation doses? When assessing radioactive contamination, the UN Commission differentiates between the acute high-dose radiation to which the workers and rescue personnel at the reactor were exposed and the decades-long chronic low radiation of the population (see Dtsch Arztebl 2011; 108 [11]: A 565).

In Chernobyl, most workers died after exposure to whole-body radiation doses greater than 4,000 millisieverts (mSv). According to UNSCEAR, the average effective dose for the various groups of people in the vicinity of the Chernobyl reactor was:

  • at 120 mSv (from 10 to 1,000 mSv) for the 530,000 workers and emergency workers ("liquidators") who were busy cleaning the reactor system and constructing the protective jacket for many months,
  • at 30 mSv for 115,000 evacuated people and
  • at 9 mSv during the first two decades for those people who continued to live in the contaminated areas,
  • below 1 mSv in the first year after the disaster for the European countries of the northern hemisphere, and gradually decreasing in the following years.

For comparison: In Germany the mean background radiation is 2.1 mSv per year (with regional fluctuations between 1 and 5 mSv). And with radiation therapy, the tumor tissue is irradiated with 50 to 60 Gray, which corresponds to a partial body radiation dose of 50,000 to 60,000 mSv. Because the doses are distributed over a longer period of time, there is no direct radiation damage.

The workers in the vicinity of the reactor in Fukushima are said to have been "irradiated" with a dose of around 170 mSv. In Germany, adults who are exposed to radioactive radiation through their work are not allowed to ingest more than 100 mSv within five years, whereby no more than 50 mSv may be reached in a single year.

Burns, infections, and skin grafts

For the UN Commission it is certain that of the 134 people who were employed in the nuclear power plant at the time of the explosion, 28 died within the first three months of the acute effects of radiation exposure. They were among the 600 workers who were on the reactor site the day after the explosion. Another 106 developed acute radiation sickness and had to be treated for years for burns, infections and skin grafts. By 2006, 19 people died in their circle, but "from different causes, not necessarily caused by the radiation," says the report.

In the case of the 530,000 liquidators, there are indications of “slightly increased rates” of leukemia and cataracts. It is known that clouding of the lens of the eye is caused by relatively low doses of radiation. In addition, no evidence of radiation-related health impairments was found, the UN committee concluded. The effects of radioactivity on the development of cardiovascular diseases are also largely unexplored.

Further cancer diseases "cannot be ruled out"

For the general population, an increased carcinogenic risk has so far hardly been discernible. Although the UN experts “cannot rule out” cancers as a result of the reactor accident, the data situation is not sufficient for unambiguous associations; they referred to the smoldering argument among scientists as to whether there is a threshold value for damage from radioactive radiation or whether the risk increases linearly.

Fukushima 2011: Removal of workers who were exposed to such strong radiation at the damaged nuclear power plant that they had to be admitted to a clinic.

However, the UN Commission sees a clear allocation to the reactor accident in the increase in diagnosed thyroid carcinomas: If it spoke of less than 2,000 additional cancers for a long time, 6,000 are now considered certain; 15 patients died as a result of this type of tumor. Affected are people who were children and adolescents (between 0 and 18 years of age) at the time of the accident.

The thyroid cancer is mainly due to the consumption of iodine-131 contaminated milk and leafy vegetables. "The real effects on public health will only become apparent with increasing age of those affected," emphasized the US radiologist Prof. Fred Mettler in Vienna. This is because thyroid cancer does not occur more frequently until the age of 40.

Particularly high risk of cancer in children under four years of age

A clear dose-response relationship for thyroid carcinomas is also confirmed by doctors at the Institute for Endocrinology and Metabolism in Kiev, who recently published the results of a cohort study with around 13,000 children and adolescents (Environmental Health Perspectives 2011; doi: 10.1289 / ehp.1002674). During a follow-up period of 73,000 person-years, 65 thyroid carcinomas were diagnosed. The - purely arithmetical - radiation exposure was between 0.09 and 48 gray. With every gray of exposure, the statistical risk of thyroid cancer doubled. The risk was highest for people who were younger than four years old at the time of the reactor accident.

The UN Commission does not anticipate any new dangers for the general public from Chernobyl. “The measurements have shown that the radioactive radiation in the exclusion zone has largely decreased within a radius of 30 kilometers from the facility. It's like going for an X-ray, ”said Crick in Vienna.

UN data arouse criticism from some institutions

The data from the UN Commission, however, do not go unchallenged due to different interests: Roland Scheidegger, radiation biologist at the Federal Nuclear Safety Inspectorate in Brugg, Switzerland, considers the data situation on Chernobyl to be poor ("Neue Zürcher Zeitung" of March 20) because it is in the former Soviet Union hardly any cancer registries had been kept. "Before the disaster, the health system was rudimentary, afterwards it was very modern," said Scheidegger. With better diagnostic methods, more cancer cases can now be recognized automatically - so an observed increase in tumor diseases could also be an artifact.

In 2006, the nuclear-critical doctors' organization IPPNW published completely different figures together with the Society for Radiation Protection e.V. The study on the health consequences of Chernobyl is based on scientific work, assessments by experts and official information from authorities. The analysis of the Chernobyl consequences would, however, be made more difficult by the considerable migration of people from the areas polluted with radioactivity to less polluted areas. In addition, a lot of data is not freely accessible because it is subject to "secrecy" in East and West.

"Neither the governments in Russia, Belarus and Ukraine, nor the western states that operate nuclear power plants, nor the relevant United Nations organizations have any interest in comprehensive and publicly verifiable research into the consequences of Chernobyl," says Pflugbeil. In addition, there is the language barrier, which has led to important studies published in Russian being ignored by Western experts.

Increase in deformities, miscarriages and stillbirths

During the current situation in Japan, Pflugbeil considers an expansion of the evacuation zone around the damaged Fukushima nuclear power plant to be urgently necessary. Together with the IPPNW, he asks the Japanese government to carry out the evacuation of the population in a timely and extensive manner so that in particular the protection of children and pregnant women is guaranteed. According to him, the recommendation of the US nuclear authority to extend the evacuation zone to 80 kilometers could be a first step.

The International Atomic Energy Agency (IAEA) and the World Health Organization (WHO), however, have been accusing the IPPNW of inconsistencies in the presentation of the Chernobyl consequences for years. Just a few days ago, she asked the federal government to work towards the WHO finally informing the public independently about the health effects of ionizing radiation. “The WHO response to the Fukushima nuclear disaster is completely inadequate. We fear a conflict of interests with the IAEA, which has been downplaying the risks of nuclear energy for years, ”explains Angelika Claußen from IPPNW to Deutsches Ärzteblatt.

The data from UNSCEAR are contrasted with other research results, for example those of the biologist Alexej Jablokow, a member of the Russian Academy of Sciences. "He assumes 900,000 to 1.8 million deaths worldwide," reports Claussen, "the figures also include future deaths because the Chernobyl nuclides remain in the biosphere." Study only on the area around Chernobyl.

Humanitarian aid in and from Germany is in demand

“After all, the largest proportion of radiation exposure, namely 53 percent, fell on other European countries than Russia, Belarus and the Ukraine. This is confirmed by the measurements of the Italian researcher Marc DeCort for the European Union in 1998, ”says the IPPNW doctor. The enormous increase in serious malformations, miscarriages and stillbirths both in the Chernobyl region and in Europe is completely ignored by UNSCEAR.

For Claussen it is clear: “Nuclear power is a high-risk technology. It is not manageable, from uranium mining to ongoing operations to the worst-case scenario and the unsolved repository problem. It makes us humans and especially our children sick. ”Even global climate changes cannot be stopped with atomic energy, which only contributes two percent to the world's energy supply.

“The victims of the Chernobyl disaster still need our help,” says Claussen with conviction, referring to numerous associations that work with IPPNW doctors and are committed to medical and humanitarian support for the people in Belarus and Ukraine. One of these committed doctors is Dr. med. Dorothea Wagner-Kolb from Hamburg, who founded the “Friends of Chernobyl Children” five years after the reactor disaster and in 2009 received the Federal Cross of Merit on ribbon for her commitment.

"Every year we have organized vacation holidays for children from socially disadvantaged families who live in the neighboring villages of the 30-kilometer exclusion zone around Chernobyl," reports Wagner-Kolb. Even if these children do not suffer from specific illnesses, their immune systems are often weakened and their development is lagging behind, or they have already experienced a lot of emotional suffering from the death of parents or close relatives.

Chernobyl cancer? Pediatrician Dr. med. Kerstin Lieber does not try to establish causality. Since 1985 she has cared for almost 700 children from Belarus with cancer. Photo: Manfred Karremann

In contrast, Dr. med. Kerstin Lieber, pediatrician and palliative medicine specialist at the Sonnenhof children's hospice in Berlin. She has been in close contact for years with the “Borowjani” children's clinic near Minsk, which she only visited a few weeks ago. She helped the doctors on site to set up the therapy and medical rehabilitation of children with tumors. In the last 18 years, Lieber also ensured that more than 700 children and young people in Germany were operated on or provided with prostheses. The association “Help for Chernobyl Children with Cancer”, which was set up by Lieber, bears the costs.

Associations organize and finance the therapies

Every year between 200,000 and 600,000 euros in donations, mainly from the population of Berlin, but also from medical colleagues, are deposited into the association's account. “Every euro is used to care for the children,” says Lieber. The administration is done on a voluntary basis. While a large part of the donations used to be invested in building up the local supply and training for Belarusian colleagues, today the money is used almost exclusively for the therapy of children with cancer and for tumor endoprostheses. “If our Belarusian colleagues feel overwhelmed with the therapy of some children, they send the children with their mothers to us in Germany. We then get in touch with specialists and organize and finance the treatment and prosthetic care, ”reports the chairwoman of the association. Mainly children and adolescents with brain tumors between the ages of two and 18 are concerned.

Lieber founded the association 18 years ago. At that time she was working on oncology at the Berlin Charité and cared for a girl from the Chernobyl region who was suffering from a bone tumor. Since then, the mother of three has not let go of the desire to help those affected. However, Lieber is no longer trying to answer the question of whether there is a connection between the Chernobyl meltdown and cancer.

“There are simply no reliable numbers and no comparative data,” she explains. "The abortion rate in the region was not recorded, and no abortions were re-examined." One can only speculate about the reasons: "The population of the Chernobyl region was a people without hope from the start," is her conviction.

"Perhaps no one bothered about them because the consequences could not have been averted anyway." It has been proven that only thyroid cancer has increased among Belarusian children. It is about 30 times more common than before the accident. Although she cannot prove that her patients were sick as a direct result of Chernobyl, that is not important to her, says Lieber. "I just want to help these children."

Dr. med. Vera Zylka-Menhorn
Dr. med. Eva Richter-Kuhlmann
Dr. rer. nat. Marc Meissner

@The UN report on the Internet:
www.aerzteblatt.de/11700

Artificial and natural radiation exposure

The release of radioactive substances in the event of a reactor accident has far-reaching consequences: On the one hand, there is direct radiation damage to the workers in the nuclear power plant and to the emergency services. On the other hand, the released radioisotopes contaminate large areas and thus end up in food and drinking water. This does not lead to direct radiation damage, but it does increase exposure to so-called low radiation.

This is essentially not caused by the radiation that the radioisotopes give off to the environment. Since it is alpha radiation, it not only has a short range (less than two meters), but can also be completely shielded by a sheet of paper. The main problem is the absorption of radioactive iodine and cesium with food. While iodine has already subsided after about two months due to its short half-life of eight days, cesium remains in the body as a radiation source for much longer.

Cesium-137 has a half-life of more than 30 years, so that it takes several centuries before radiation can no longer be measured. In this case, the biological half-life is more relevant, because cesium absorbed by the body is excreted after about 110 days. This also applies to the radioactive isotopes, so that cesium-137, for example, remains in the body for up to three years (around ten biological half-lives).

Even if the consequences of low radiation are very controversial, one thing is clear: the more radiation you are exposed to, the higher the risk of cancer. Every time ionizing radiation - such as radioactive or X-rays - hits the body, there can be a change in the genetic make-up. How often this happens depends on the type of radiation. If you are exposed to the same amounts of radioactive and X-ray radiation, then, for example, the chance of genetic damage from radioactive radiation is 20 times higher. In order to indicate the exposure independently of the type of radiation, the unit Sievert (Sv) has been established, in which the strength of the radiation and its biological effectiveness are offset.

However, damage to the genetic makeup does not necessarily mean that there is a mutation and thus possibly cancer, because the individual cells have appropriate repair mechanisms. Only when these fail does a change occur in the genetic make-up.

Radiation does not only occur in connection with artificial sources. We are also exposed to natural radiation on a daily basis, which is caused by radioactive isotopes in the environment or cosmic rays. In Germany, this exposure is 2 to 5 millisieverts (mSv) per year. For comparison: an X-ray examination is around 0.1 mSv, a continental flight around 0.02 mSv.

If you add up the artificial and natural radiation exposure in Germany, then this is around 4 mSv per year. Only 0.02 mSv, i.e. only one two hundredth of the radiation exposure, can be attributed to the consequences of the reactor accident in Chernobyl. The small proportion of artificial radioactivity in the total radiation exposure is the reason why the health consequences of low radiation are difficult to determine.

A connection between radiation exposure and cancer can only be proven in statistics.

Measured quantities and units

When atomic nuclei disintegrate, different types of particle radiation and electromagnetic radiation are created, the amount, energy content and biological effectiveness of which differ from element to element, from type of radiation to type of radiation. Depending on which statements are to be made about the radioactive material, experts use different measurement parameters with their units of measurement.

  • The activity measured in Becquerel (Bq) indicates how many radioactive nuclei disintegrate per second, producing what is known as radioactive radiation. The Becquerel can be heard quite clearly if you use a Geiger counter or another measuring device for radioactivity: A "crack" is a radioactive decay, once per second this means "1 Becquerel", at 100 clicks per second it is "100 Becquerel".
  • The dose, measured in gray (Gy), indicates how much energy (in joules) is absorbed by radiation per kilogram of body weight.
  • The equivalent dose is measured in Sievert (Sv). It is calculated from the energy of the radiation and its biological effectiveness, which can vary depending on the type of radiation. Since a sievert is a relatively large unit, experts speak of millisievert (= one thousandth sievert)
  • The dose rate indicates how much energy per time (i.e. power) is absorbed per kilogram. Usually this is small and is in the range of a few thousandths of a sievert (millisievert) per year.

Current measured values ​​are also given as hourly values. In the reports on the damaged Fukushima power plant in Japan, values ​​of a few hundred mSv were reported, always referring to mSv / h.

(Source: World of Physics, published by the German Physical Society, the Federal Ministry of Research and the Physikalisch-Technische Bundesanstalt)