Syndrome of acute irradiation

The syndrome of acute irradiation (or, in the past, disease of the rays ) indicates a whole of Symptôme S potentially mortals who result from a specific exposure of the biological fabrics of an important part of the body to strong a amount of ionizing rays, in particular with a intense Radioactivité.

It generally appears by a prodromic Phase nonlethal in the minutes or hours which follow the irradiation. It lasts a few hours at a few days and generally appears by the following symptoms: Diarrhea, nausea, Vomiting S, Anorexia (lack of appetite), erythema (rednesses of Skin). Follows a Latency period , apparent cure, all the more short as the irradiation is severe; it lasts a few hours at a few weeks. Lastly, occurs the acute phase, potentially mortal, who appear by a vast spectrum of possible symptoms, of which most frequent are related to hematopoietic disorders (production of the cell S Sang uines), gastro-intestinal, cutaneous, respiratory S and cérébro-vascular.

The natural radiation sources are not generally enough powerful to cause the syndrome, so that it generally results from human activities: Nuclear accident serious in a Laboratory or a Nuclear plant (Accident of criticality for example), exposure to a powerful radioactive source (medical source or of instrumentation) or atomic Explosion.

History and context

See also: atomic Bombardments of Hiroshima and Nagasaki, List of the nuclear accidents, Nuclear weapon

If the effects of the chronic irradiation started to be known in the pioneers of the radioactivity (e.g. Marie Curie) and certain workers of the nuclear power (Soviet nuclear program), it is only at the time of the atomic Bombardements of Hiroshima and Nagasaki that the effects of an acute irradiation were discovered: the drama of the Hibakusha (“victims of the bombardments”) was quickly known of the general public and was the subject of medical studies.

Thereafter, some nuclear accidents and radiological caused victims: Accident of criticality during experiments (the case of Louis Slotin is most known) or in nuclear reactors (Catastrophe of Tchernobyl); repercussions of the Nuclear test Castle Cheer of the American program; accidental exposure to radioactive sources of sterilization, Radiotherapy or generation of heat.

In the case of Tchernobyl and according to the documents of the International Atomic Energy Agency the number of deaths following a syndrome of acute irradiation would be approximately 28.

Notwithstanding, the syndrome was largely studied by the nuclear powers with fine soldiers offensives and defensives. For the attack, the Bombe with neutrons is intended to make the personnel immediately inapt for the combat by acute irradiation; the bombs salted (with strong repercussions) to contaminate grounds like technique of area denial (prohibition of zone). Defense vis-a-vis a major nuclear threat justified studies on the prevention and the treatment of the disease.

Impact of the irradiation on fabrics

Measure exposure

The measurement of the impact of an exposure to radiations takes into account three principal factors: the energy deposited in a fabric by the radiation, the relative impact of the type of radiation, the sensitivity relative of fabric to the ionizing rays.

The three principal sizes are used:

  • the radiative Amount D T, R is the energy by unit of Masse deposited by a radiation R in a fabric T. Its unit in the international system is the Gray (1 Gy = 1 J/kg).
  • l' equivalent of amount is the corrected radiative amount of the impact of the radiation (relative biological effectiveness) and is measured in Sievert S (Sv); it is given by H T = W R D T, R, where W R is the factor loading of the radiation.
  • L' effective equivalent of amount is the corrected radiative amount of the impact of the radiation and the sensitivity of fabric. It is measured in Sv and is given by E = W T H T, where W T is the factor loading of the fabric .

The physical sizes measuring the impact of the exposure (equivalent of amount and effective equivalent of amount) are traditionally defined to describe the stochastic effects of the chronic irradiation, i.e. to predict the probability of which has occurred of diseases induced like the Leucémie S, Cancer S or the cardiovascular complications.

Biological effectiveness

The corrective factors W , as defined by the radiological International commission of protection are however not refined to describe the effects of the acute irradiation which is the object of this article. More particularly, the relative biological effectiveness of the various radiations tends to approach with high amount: if the stochastic risks of a weak irradiation (< 0,1 Gy) by neutrons requires a factor of correction W R = 5-20.

Effects at the cellular level

DNA is one of the molecules most sensitive of the cell to the ionizing rays. The mechanisms of repair make it possible to repair the majority of the lesions when the amount is managed in a sufficiently slow way or a split way, but an amount of 2 Gy or more received quickly is enough to kill a cell in the process of division; the mature cells on the other hand are not very sensitive. The second notable effect is an inhibition of the Mitose (cf appears opposite) of which the duration depends on the intensity of the irradiation.

Note: the chronic exposure to a low or moderate radioactivity, in the short or medium term does not cause symptoms but an increased risk of long-term complications such as leukemia and cancers; these stochastic effects (probabilistic) is to be distinguished from the syndrome of acute irradiation which appears in a fast and unquestionable way beyond of a certain amount of radiation (deterministic effect). The acute exposure of a small portion of the body (except for the brain, of the lungs and the spinal-cord) does not involve either a syndrome of acute irradiation but a potentially mortal dysfunction of the Organe S touched in the weeks or the months following the incident. These two effects are not the object of the present article.

Phases

With the very strong amounts (> 20-50 Gy) the Nervous system is touched; confusion, Ataxia (incoordination of the voluntary movements), Is delirious, Coma, Convulsion S, then Mort occurs a few minutes at a few hours after the exposure. One period of recovery partial of the capacities of a few hours can be observed.

For less amounts (1-20 Gy), the Syndrome is held in three phases ! style=" text-align: left" | dose rate ! style=" width: 4em" | 0,2 Gy/h ! style=" width: 4em" | 1 Gy/h ! style=" width: 4em" | 10 Gy/h ! style=" width: 4em" | 100 Gy/h |- ! style=" text-align: left" | minimal care | 4,5 || 3,7 || 3,3 || 3,3 |- ! style=" text-align: left" | intensive care | 6,4 || 5,8 || 5,3 || 5,2 |- ! style=" text-align: left" | + growth factors | 7,8 || 7,3 || 6,5 || 6,1 |} For an internal-source irradiation, the death generally takes place in the two months following the irradiation, by Infection or Hémorragie intern (1,5-10 Gy) or by dysentric Diarrhée of the type. It is attested from 1,5 Gy (fast exposure, without care) and is nearly certain beyond 10 Gy. For intermediate amounts, survival depends on intensive care. In the case of an external irradiation, by not very penetrating radiations, the Skin and the respiratory Tracts can be specifically touched; death can then occur for high amounts (> 8-10 Gy) in the weeks or month following the exposure.

In the event of survival, which has occurred of cardiovascular diseases, digestive, and respiratory in the following years is frequent. The final sterility female is possible from 2 Gy. Temporary male sterility is frequent, including with amounts not causing symptoms (from 0,15 Gy).

The elderly and the children are particularly sensitive to an acute exposure to radiation.

Forms of the syndrome of acute irradiation

There exist five principal forms of the syndrome.]]

The syndrome hematopoietic is dependant on the destruction partial or total hematopoietic cells of osseous marrow and on that of the Lymphocyte S peripherals.

In the hours following the exposure, the fall of lymphocytary numeration increases the risk of infection. The speed and the extent of the fall of numeration are an indication of the received amount and allow a diagnosis of the gravity of the irradiation in the absence of dosimetric measurement, such as for example for the civil population.

Hematopoietic deficiency is translated into a few weeks by a fall of the rate of Granulocyte S (Immunodéficience), of Thrombocyte S and plate S (defect of coagulation). That can lead to an infection mortal or internal bleedings.

The hematopoietic form of the syndrome of acute irradiation is that which causes death with most low dose, typically between 1,5 and 10 Gy (fast irradiation). The death generally intervenes, if it takes place, in the two months following the irradiation. In the severe cases of irradiation (around 5 Gy on the whole of the body), marrow is completely destroyed; survival is then possible only with one Clerc's Office. In the event of nonuniform irradiation, the surviving hematopoietic cells make it possible to repopulate marrow; survival is then possible without Clerc's Office.

According to the speed of the exposure and the type of care, a mortality of 50% is reached for an amount from 3 to 6 Gy (see figures above).

Cérébro-vascular form

The cérébro-vascular form generally appears for amounts higher than 50 Gy but the symptoms can appear as of 20 Gy]] The female sterility permanent key 60% of the patients exposed to 2,5-5 Gy (including 100% of more than 40 years) and 100% from 8 Gy. Effects among certain women of more than 40 years are observed as of 1,5 Gy.

The Azoospermie (thus sterility) male temporary is observed at 100% of the men exposed to 0,3-0,5 Gy between 4 and 12 months after the irradiation with a total recovery in the two years; the Oligozoospermie can be observed as of 0,1 Gy. Beyond 2-3 Gy, the azoospermy is observed as of the first two months following the exposure and lasts at least 3 years. Permanent sterility is attested for amounts from 5 to 15 Gy on the gonades. The delay of growth is observed at the subjects exposed to more than 1 Gy, it is about 10 cm |- ! rowspan=" 2" | decile ! colspan=" 2" | duration before vomiting |- ! < 4:00 ! > 4:00 |- | 25% || 2,5 || 0,5 |- | 50% || 3,6 || 0,9 |- | 75% || 6,0 || 1,7 |} An estimate of the received amount is necessary to know the assumption of responsibility necessary; the personnel on sensitive installations must carry for this purpose a Dosimètre. In the absence of measurement, the presence, speed of appearance and intensity of the prodromaux symptoms, as well as the numeration of the Lymphocyte S in the two days following the irradiation makes it possible to quantify the gravity of the exposure.

Measure exposure to the gammas

Diagnostic tools rapid were developed at ends of Civil security in order to be able to carry out a tri rapid of the people. They are intended for the accidents with large scales, if it proves to be impossible to quickly make an closer examination of the whole of the touched individuals. The intermediate duration T past between a specific exposure to gamma rays and the first vomiting is connected to the received amount D by a Loi of power. |- ! concentration in lymphocytes (mm-3) ! proportion (Gy) |- | 2500 || < 1 Gy |- | 1700-2500 || 1-5 Gy |- | 1200-1700 || 5-9 Gy |- | < 1000 || > 10 Gy |}

A blood assessment established in the 8 to 48 hours after the exposure makes it possible to establish an interval of received amount: the numeration of lymphocytes decreases according to a exponential Loi whose time of half-value is correlated with the gravity of the irradiation. A Lymphocytopénie of 1500 mm-3 or less in the 48h according to the exposure indicates an exposure to an average amount of 3,1 Gy. These patients will require medical care is still experimental. The measurement of the free radical rates of or biochemical markers specific is considered.

Care

There does not exist tested treatment of the consequences of an irradiation (of the causes of the symptoms), but a symptomatic treatment makes it possible to decrease mortality time that the fabrics are regenerated or that a Clerc's Office is carried out.

Assumption of responsibility

The treatment of the wounds (burns, traumatism) is priority on that of the irradiation. It is advisable to decontaminate in the event of contact, of ingestion or ingestion of radioelements.

In the event of accident implying the civil population, a psychological follow-up is necessary and certain people develop symptoms characteristic of the syndrome of acute irradiation without to have been exposed, a Effet placebo observed at nearly 5000 people at the time of the radiological accident to Goiâna to the Brésil, 1987.

Syndrome hematopoietic

The hospitalization is generally necessary only for one amount higher than 2 Gy, the risk of infections requires a placement in sterile medium. In the other cases, the care can be lavished in residence., is developed jointly by the Drug company and the American Armée. Tested at the Monkey, it would decrease the Thrombocytopénie and the Anémie resulting from an exposure to moderate amounts and would increase the chances of survival with a strong irradiation.

Syndromes gastro-intestinal and cérébro-vascular

These forms of the syndrome of acute irradiation lead to an unquestionable death. The patients require a palliative Traitement. Symptomatic care can prolong the lifespan. The armed forces were interested in symptomatic treatments in the first hours of a high irradiation (20-50 Gy) in order to allow the troops touched to be suited to the limited combat for one period.

Attested cases

The number of deaths attested by syndrome of acute irradiation is of 180 during the time of 1945 with 2004 out of 600 listed radiological accidents, Hibakusha of excluded Hiroshima and Nagasaki.

The four attested leading causes of the syndrome are the exposure to a nuclear Explosion or its repercussions, the accident on a Nuclear reactor, the Accident of criticality during the matter handling Fissile and the exposure to a powerful radiosource.

Continuations of a nuclear explosion

The nuclear explosion is without question the most popularized most known cause and syndrome of acute irradiation, in particular via the film Black Rain which reports misfortunes of the Hibakusha following the atomic Bombardements of Hiroshima and Nagasaki; a Nuclear test atmospheric American also caused the syndrome by accident:

Accidents on a nuclear reactor

The Catastrophe of Tchernobyl in 1986 popularized the risk represented by the accidents on nuclear reactors. An accident at the edge of a Soviet Sous-marin also knew the celebrity with the film K-19: The trap the depths .

No accident on a nuclear reactor caused the syndrome of acute irradiation among the civil population. Only one - the catastrophe of Tchernobyl - had an extended impact, subjecting the population and the environment to an important radioactive contamination.

The nine attested accidents are:

Accidents of criticality during fissile handling of products

The case of the physicist Louis Slotin, mortally irradiated in 1946 during a scientific demonstration to the National laboratory of Los Alamos drew the attention to the risks of fissile material handling; its history is fictionalized in the Masters of the shade . It is also the case of the accident of Tokaimura (Japan) in 1999 in a civil nuclear installation.

None the accidents of criticality during handling of fissile products caused syndrome of acute irradiation near the public; in only one case - Tokaimura in 1999 - the civil population was subjected to an exposure higher than the standards.

List accidents of criticality during a matter handling which caused an acute irradiation:

  • August 21st 1945, National laboratory of Los Alamos, the United States: Accident of criticality by handling error. Harry Daghlian Jr. drop a brick from Carbure of Tungstène reflecting the neutrons on a block of Plutonium. In addition to the usual form of the syndrome it presents serious burns to the hands as of the first days following the irradiation (200-400 Gy on the right hand). He dies three weeks afterwards.
  • 1977, Rockaway, the United States: exposure to a radioactive source. An employee of a company of irradiation receives 2 accidentally Sv of a source of Cobalt 60 and develops a syndrome of acute irradiation.
  • 1986, Kaifeng, China: exposure to a radioactive source. Two individuals receive 2,6 and 3,2 Sv of a source of Cobalt 60 and develop the syndrome of acute irradiation.
  • October 26th 1991, Niasviž, Bielorussia: accidental exposure to a source of industrial sterilization. An operator of a factory of sterilization exposes himself by inadvertency to an amount of 12,5 Sv. He survives the syndrome hematopoietic thanks to intensive care but dies at the end of four months.
  • 1994, Tammiku, Estonia: exposure following a loss of radioactive waste. A person dies of the continuations of an irradiation with 4 Gy.
  • January - February 2000, Samut Prakan, Thailand: loss of radioactive source. A medical source of Cobalt 60 tomb during a transport and is loosened. Three employees die and seven others fall sick, with amounts of about 2 Sv as well as serious burns for some.
  • June - July 2000, MIT Halfa, Egypt: loss of radioactive sources. An employee finds a source radioactive of Iridium 192 and brings back it at his place. Seven people fall sick, of which two die; tens of neighbors present minor modifications of the blood picture.
  • 2001 - 2002, Liya, Georgia: flight of radioactive sources. Sources of 90strontium being used as thermoelectric Générateur with radioisotope are flights; three people develop the syndrome of acute irradiation.

Other accidents