Radiation poisoning

Radioactive hazard symbol.

Radiation poisoning or acute radiation syndrome is the set of negative health effects caused by exposure to excessive amounts of ionizing radiation.

The term is generally used to refer to acute problems due to one of the severe doses of radiation absorbed in a short period of time. Many of the symptoms of radiation poisoning occur when ionizing radiation interferes with the process of cell division. This interference causes particular problems for cells with high turnover rates, cells that would normally reproduce rapidly. For example, the cells that line the inner part of the gastrointestinal tract or the hematopoietic cells of the bone marrow.

Units for radiation measurement

The Roentgen (R) is the measure of the electrical charge produced by X (ionization) or gamma radiation deposited in dry air under standard conditions. Defined as the electric charge deposited by 1 gram of radium-226 measured at one yard distance in one hour, it was replaced by the unit X (C/kg) included in the international system of units, but without a defined name yet, with what is still more popular for this magnitude is the old unit.

The rad (acronym for radiation absorbed dose) is a unit of absorbed dose in terms of energy deposited in matter. The rad was defined as an absorbed dose of 100 ergs of energy per gram of matter.

The most recent unit of absorbed dose, used in the international system of units, is the gray, which is defined as 1 joule of energy deposited per kilogram of matter. The equivalence between both units is 1 Gy = 100 rad.

To determine radiation risk, the "relative biological efficacy" of radiation, obtaining a correction factor (Q before, RBE now) that multiplying to the absorbed dose results in a direct measurement of the biological effective dose. This biological effective dose, or simply effective dose, is measured in rem (acronym for roentgen equivalent man), which is equal to the "radiation dose" absorbed (measured in rads) multiplied by a "quality factor" which assesses the effectiveness of each particular type of radiation.

In the international system of units, "relative fitness" of radiation is measured in sieverts (Sv), which is equal to 100 rems.

For alpha particles the "relative fitness" it can be worth 20, so that a rad would be equivalent to 20 rems. The same is applicable to neutron radiation. On the other hand, for beta particles, x-rays and gamma rays, the "relative biological efficacy" It is valued as 1, so in these types of radiation, the rad and the rem would be equivalent.

Symptoms and effects

The symptoms of radiation sickness become more serious (and the chance of survival decreases) when the radiation dose is increased.

Chronic exposure to ionizing radiation can cause leukemia and other cancers. The ability of radiation to prevent cell division is also used in the treatment of cancer (radiotherapy).

Other symptoms of radiation poisoning include hair loss, diarrhea, fatigue, nausea, vomiting, fainting, skin burns, and at high doses, death.

An extremely high whole-body dose of radiation, such as 100 Sv (10,000 rems) causes unconsciousness and death in a short period, as nerve cells are destroyed.

A lower (but still high) dose would cause immediate severe illness, after which the victim appears to recover, only to die a few days later when the rapidly dividing intestinal cells fail.

Radiation poisoning can result from accidental exposure to natural or industrial sources of radiation. People who work with radioactive materials often wear dosimeters to monitor their total radiation exposure. These devices are better suited than Geiger counters for determining biological effects, since they measure cumulative exposure over time, and are calibrated to change color or provide some type of signal that alerts the user before exposure reaches unsafe levels..

Radioactivity caused illness and death after the bombings of Hiroshima and Nagasaki in about 1% of those exposed who survived the initial explosions. The death rate due to radiation was highest in Hiroshima, because although Fat Man (the name of the bomb used on Nagasaki) had a higher yield than Little Boy (the name of the bomb used on Hiroshima), Fat Man was a plutonium weapon, which for the same output was much less radioactive than a uranium weapon.

Radiation poisoning remains a major concern after the Chernobyl nuclear reactor accident. Of the 100 million curies (4 exabecquerels) of radioactive material released, the radioactive isotopes xenon-133 and iodine-131 were initially the most dangerous. Due to their short half-lives they have now declined, leaving the longer half-lived products (such as cesium-137 and strontium-90) as the most dangerous at this time.

Health effects

Joules per kilogram of living matter

Equivalent doses are given in sieverts. The siervert measures the amount of energy in joules absorbed by one kg of living matter. The symptoms correspond to an irradiation of the whole body with an average dose equal to the indicated value.

The radiation dose is expressed in Grays. Mortality without further care.Mortality with subsequent care.

Joules per kilogram of matter

Absorbed doses are indicated in gray. Unlike the siervert, the gray does not distinguish between living and non-living matter. The mortality rate indicates the percentage chance of death in any period of time after exposure to radiation, as long as the radiation has not been treated.