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Radiobiology (also known as radiation biology, and uncommonly as actinobiology) is a field of clinical and basic
medical sciences Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care pr ...
that involves the study of the action of
ionizing radiation Ionizing radiation (or ionising radiation), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel ...
on living things, especially health effects of radiation. Ionizing radiation is generally harmful and potentially lethal to living things but can have health benefits in
radiation therapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Rad ...
for the treatment of cancer and thyrotoxicosis. Its most common impact is the induction of cancer with a latent period of years or decades after exposure. High doses can cause visually dramatic
radiation burns A radiation burn is a damage to the skin or other biological tissue and organs as an effect of radiation. The radiation types of greatest concern are thermal radiation, radio frequency energy, ultraviolet light and ionizing radiation. The mos ...
, and/or rapid fatality through acute radiation syndrome. Controlled doses are used for
medical imaging Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to re ...
and
radiotherapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Rad ...
.


Health effects

In general, ionizing radiation is harmful and potentially lethal to living beings but can have health benefits in
radiation therapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Rad ...
for the treatment of cancer and thyrotoxicosis. Most adverse health effects of radiation exposure may be grouped in two general categories: *deterministic effects (harmful tissue reactions) due in large part to the killing/ malfunction of cells following high doses; and *stochastic effects, i.e., cancer and heritable effects involving either cancer development in exposed individuals owing to mutation of somatic cells or heritable disease in their offspring owing to mutation of reproductive (germ) cells.


Stochastic

Some effects of ionizing radiation on human health are
stochastic Stochastic (, ) refers to the property of being well described by a random probability distribution. Although stochasticity and randomness are distinct in that the former refers to a modeling approach and the latter refers to phenomena themselv ...
, meaning that their probability of occurrence increases with dose, while the severity is independent of dose. Radiation-induced cancer, teratogenesis, cognitive decline, and
heart disease Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, h ...
are all stochastic effects induced by ionizing radiation. Its most common impact is the stochastic induction of cancer with a latent period of years or decades after exposure. The mechanism by which this occurs is well understood, but quantitative models predicting the level of risk remain controversial. The most widely accepted model posits that the incidence of cancers due to ionizing radiation increases linearly with effective radiation dose at a rate of 5.5% per
sievert The sievert (symbol: SvNot be confused with the sverdrup or the svedberg, two non-SI units that sometimes use the same symbol.) is a unit in the International System of Units (SI) intended to represent the stochastic health risk of ionizing rad ...
. If this
linear model In statistics, the term linear model is used in different ways according to the context. The most common occurrence is in connection with regression models and the term is often taken as synonymous with linear regression model. However, the term ...
is correct, then natural
background radiation Background radiation is a measure of the level of ionizing radiation present in the environment at a particular location which is not due to deliberate introduction of radiation sources. Background radiation originates from a variety of source ...
is the most hazardous source of radiation to general public health, followed by medical imaging as a close second. Quantitative data on the effects of ionizing radiation on human health is relatively limited compared to other medical conditions because of the low number of cases to date, and because of the stochastic nature of some of the effects. Stochastic effects can only be measured through large epidemiological studies where enough data has been collected to remove confounding factors such as smoking habits and other lifestyle factors. The richest source of high-quality data comes from the study of Japanese
atomic bomb survivors ''Hibakusha'' ( or ; ja, 被爆者 or ; "person affected by a bomb" or "person affected by exposure o radioactivity) is a word of Japanese origin generally designating the people affected by the atomic bombings of Hiroshima and Nagasaki at th ...
. In vitro and animal experiments are informative, but radioresistance varies greatly across species. The added lifetime risk of developing cancer by a single abdominal CT of 8 
mSv mSv or MSV may refer to: * Maize streak virus, a plant disease * Medium-speed vehicle, US category * Medium Systems Vehicle, a class of fictional artificially intelligent starship in The Culture universe of late Scottish author Iain Banks * Millis ...
is estimated to be 0.05%, or 1 in 2,000.


Deterministic

Deterministic Determinism is a philosophical view, where all events are determined completely by previously existing causes. Deterministic theories throughout the history of philosophy have developed from diverse and sometimes overlapping motives and cons ...
effects are those that reliably occur above a
threshold dose Threshold dose is the minimum dose of drug that triggers minimal detectable biological effect in an animal. At extremely low doses, biological responses are absent for some of the drugs. The increase in dose above threshold dose induces an increase ...
, and their severity increases with dose.Note: first page available free at URL. High radiation dose gives rise to deterministic effects which reliably occur above a threshold, and their severity increases with dose. Deterministic effects are not necessarily more or less serious than stochastic effects; either can ultimately lead to a temporary nuisance or a fatality. Examples of deterministic effects are: * Acute radiation syndrome, by acute whole-body radiation *
Radiation burn A radiation burn is a damage to the skin or other biological tissue and organs as an effect of radiation. The radiation types of greatest concern are thermal radiation, radio frequency energy, ultraviolet light and ionizing radiation. The m ...
s, from radiation to a particular body surface * Radiation-induced thyroiditis, a potential side effect from radiation treatment against
hyperthyroidism Hyperthyroidism is the condition that occurs due to excessive production of thyroid hormones by the thyroid gland. Thyrotoxicosis is the condition that occurs due to excessive thyroid hormone of any cause and therefore includes hyperthyroidis ...
*
Chronic radiation syndrome Chronic radiation syndrome (CRS), or chronic radiation enteritis, is a constellation of health effects of radiation that occur after months or years of chronic exposure to high amounts of radiation. Chronic radiation syndrome develops with a speed ...
, from long-term radiation. * Radiation-induced lung injury, from for example
radiation therapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Rad ...
to the lungs * Cataracts and infertility. The US National Academy of Sciences Biological Effects of Ionizing Radiation Committee "has concluded that there is no compelling evidence to indicate a dose threshold below which the risk of tumor induction is zero".


By type of radiation

When alpha particle emitting isotopes are ingested, they are far more dangerous than their half-life or decay rate would suggest. This is due to the high
relative biological effectiveness In radiobiology, the relative biological effectiveness (often abbreviated as RBE) is the ratio of biological effectiveness of one type of ionizing radiation relative to another, given the same amount of absorbed energy. The RBE is an empiric ...
of alpha radiation to cause biological damage after alpha-emitting radioisotopes enter living cells. Ingested alpha emitter radioisotopes such as transuranics or actinides are an average of about 20 times more dangerous, and in some experiments up to 1000 times more dangerous than an equivalent activity of beta emitting or gamma emitting radioisotopes. If the radiation type is not known, it can be determined by differential measurements in the presence of electrical fields, magnetic fields, or with varying amounts of shielding.


In pregnancy

The risk for developing radiation-induced cancer at some point in life is greater when exposing a fetus than an adult, both because the cells are more vulnerable when they are growing, and because there is much longer lifespan after the dose to develop cancer. If there is too much radiation exposure there could be harmful effects on the unborn child or reproductive organs. Research shows that if there is more than 1 scan in 9 month it can harm your unborn child. Possible deterministic effects include of radiation exposure in pregnancy include
miscarriage Miscarriage, also known in medical terms as a spontaneous abortion and pregnancy loss, is the death of an embryo or fetus before it is able to survive independently. Miscarriage before 6 weeks of gestation is defined by ESHRE as biochemica ...
, structural
birth defect A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities ca ...
s, growth restriction and
intellectual disability Intellectual disability (ID), also known as general learning disability in the United Kingdom and formerly mental retardation, Rosa's Law, Pub. L. 111-256124 Stat. 2643(2010). is a generalized neurodevelopmental disorder characterized by signif ...
. February 2016 The deterministic effects have been studied at for example survivors of the
atomic bombings of Hiroshima and Nagasaki The United States detonated two atomic bombs over the Japanese cities of Hiroshima and Nagasaki on 6 and 9 August 1945, respectively. The two bombings killed between 129,000 and 226,000 people, most of whom were civilians, and remain the onl ...
and cases where
radiation therapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Rad ...
has been necessary during pregnancy: The intellectual deficit has been estimated to be about 25 IQ points per 1,000 mGy at 10 to 17 weeks of gestational age. These effects are sometimes relevant when deciding about medical imaging in pregnancy, since
projectional radiography Projectional radiography, also known as conventional radiography, is a form of radiography and medical imaging that produces two-dimensional images by x-ray radiation. The image acquisition is generally performed by radiographers, and the images a ...
and CT scanning exposes the fetus to radiation. Also, the risk for the mother of later acquiring radiation-induced
breast cancer Breast cancer is cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, milk rejection, fluid coming from the nipple, a newly inverted nipple, or ...
seems to be particularly high for radiation doses during pregnancy.


Measurement

The human body cannot sense ionizing radiation except in very high doses, but the effects of ionization can be used to characterize the radiation. Parameters of interest include disintegration rate, particle flux, particle type, beam energy, kerma, dose rate, and radiation dose. The monitoring and calculation of doses to safeguard human health is called dosimetry and is undertaken within the science of health physics. Key measurement tools are the use of
dosimeter A radiation dosimeter is a device that measures dose uptake of external ionizing radiation. It is worn by the person being monitored when used as a personal dosimeter, and is a record of the radiation dose received. Modern electronic personal d ...
s to give the external effective dose uptake and the use of bio-assay for ingested dose. The article on the
sievert The sievert (symbol: SvNot be confused with the sverdrup or the svedberg, two non-SI units that sometimes use the same symbol.) is a unit in the International System of Units (SI) intended to represent the stochastic health risk of ionizing rad ...
summarises the recommendations of the ICRU and ICRP on the use of dose quantities and includes a guide to the effects of ionizing radiation as measured in sieverts, and gives examples of approximate figures of dose uptake in certain situations. The committed dose is a measure of the stochastic health risk due to an intake of radioactive material into the human body. The ICRP states "For internal exposure, committed effective doses are generally determined from an assessment of the intakes of radionuclides from bioassay measurements or other quantities. The radiation dose is determined from the intake using recommended dose coefficients".


Absorbed, equivalent and effective dose

The
absorbed dose Absorbed dose is a dose quantity which is the measure of the energy deposited in matter by ionizing radiation per unit mass. Absorbed dose is used in the calculation of dose uptake in living tissue in both radiation protection (reduction of har ...
is a physical dose quantity ''D'' representing the mean energy imparted to
matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic part ...
per unit mass by
ionizing radiation Ionizing radiation (or ionising radiation), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel ...
. In the SI system of units, the unit of measure is joules per kilogram, and its special name is
gray Grey (more common in British English) or gray (more common in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning literally that it is "without color", because it can be compose ...
(Gy). The non-SI CGS unit rad is sometimes also used, predominantly in the USA. To represent stochastic risk the
equivalent dose Equivalent dose is a dose quantity '' H '' representing the stochastic health effects of low levels of ionizing radiation on the human body which represents the probability of radiation-induced cancer and genetic damage. It is derived from the p ...
''H'' T and effective dose ''E'' are used, and appropriate dose factors and coefficients are used to calculate these from the absorbed dose. Equivalent and effective dose quantities are expressed in units of the
sievert The sievert (symbol: SvNot be confused with the sverdrup or the svedberg, two non-SI units that sometimes use the same symbol.) is a unit in the International System of Units (SI) intended to represent the stochastic health risk of ionizing rad ...
or
rem Rem or REM may refer to: Music * R.E.M., an American rock band * ''R.E.M.'' (EP), by Green * "R.E.M." (song), by Ariana Grande Organizations * La République En Marche!, a French centrist political party * Reichserziehungsministerium, in Nazi ...
which implies that biological effects have been taken into account. These are usually in accordance with the recommendations of the International Committee on Radiation Protection (ICRP) and International Commission on Radiation Units and Measurements (ICRU). The coherent system of radiological protection quantities developed by them is shown in the accompanying diagram.


Organizations

The International Commission on Radiological Protection (ICRP) manages the International System of Radiological Protection, which sets recommended limits for dose uptake. Dose values may represent absorbed, equivalent, effective, or committed dose. Other important organizations studying the topic include * International Commission on Radiation Units and Measurements (ICRU) *
United Nations Scientific Committee on the Effects of Atomic Radiation The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) was set up by resolution of the United Nations General Assembly in 1955. 21 states are designated to provide scientists to serve as members of the committee whic ...
(UNSCEAR) *US National Council on Radiation Protection and Measurements (NCRP) *UK
Public Health England Public Health England (PHE) was an executive agency of the Department of Health and Social Care in England which began operating on 1 April 2013 to protect and improve health and wellbeing and reduce health inequalities. Its formation came as ...
*US
National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the Nat ...
(NAS through the BEIR studies) *French
Institut de radioprotection et de sûreté nucléaire The French ''Institut de radioprotection et de sûreté nucléaire'' (IRSN) ("Radioprotection and Nuclear Safety Institute") located in Fontenay-aux-Roses is a public official establishment with an industrial and commercial aspect (EPIC) created b ...
(IRSN) *
European Committee on Radiation Risk The European Committee on Radiation Risk (ECRR) is an informal committee formed in 1997 following a meeting by the European Green Party at the European Parliament to review the Council of Europe's directive ''96/29Euratom'', issued in May of the pr ...
(ECRR) the stage of radiation depends on the stage the body parts are affected


Exposure pathways


External

External exposure is exposure which occurs when the radioactive source (or other radiation source) is outside (and remains outside) the organism which is exposed. Examples of external exposure include: * A person who places a sealed radioactive source in his pocket * A space traveller who is irradiated by
cosmic ray Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own ...
s * A person who is treated for
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
by either teletherapy or
brachytherapy Brachytherapy is a form of radiation therapy where a sealed radiation source is placed inside or next to the area requiring treatment. ''Brachy'' is Greek for short. Brachytherapy is commonly used as an effective treatment for cervical, pro ...
. While in brachytherapy the source is inside the person it is still considered external exposure because it does not result in a committed dose. * A nuclear worker whose hands have been dirtied with radioactive dust. Assuming that his hands are cleaned before any radioactive material can be absorbed, inhaled or ingested, skin contamination is considered to be external exposure. External exposure is relatively ''easy'' to estimate, and the irradiated organism does not become radioactive, except for a case where the radiation is an intense
neutron The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the atomic nucleus, nuclei of atoms. Since protons and ...
beam which causes
activation Activation, in chemistry and biology, is the process whereby something is prepared or excited for a subsequent reaction. Chemistry In chemistry, "activation" refers to the reversible transition of a molecule into a nearly identical chemical o ...
.


By type of medical imaging


Internal

Internal exposure occurs when the radioactive material enters the organism, and the radioactive atoms become incorporated into the organism. This can occur through inhalation, ingestion, or injection. Below are a series of examples of internal exposure. * The exposure caused by
potassium-40 Potassium-40 (40K) is a radioactive isotope of potassium which has a long half-life of 1.25 billion years. It makes up about 0.012% (120 ppm) of the total amount of potassium found in nature. Potassium-40 undergoes three types of radioactive d ...
present within a ''normal'' person. * The exposure to the ingestion of a soluble radioactive substance, such as 89Sr in cows'
milk Milk is a white liquid food produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals (including breastfed human infants) before they are able to digest solid food. Immune factors and immune-modulat ...
. * A person who is being treated for cancer by means of a radiopharmaceutical where a radioisotope is used as a drug (usually a liquid or pill). A review of this topic was published in 1999. Because the radioactive material becomes intimately mixed with the affected object it is often difficult to decontaminate the object or person in a case where internal exposure is occurring. While some very insoluble materials such as
fission product Nuclear fission products are the atomic fragments left after a large atomic nucleus undergoes nuclear fission. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons, the release ...
s within a
uranium dioxide Uranium dioxide or uranium(IV) oxide (), also known as urania or uranous oxide, is an oxide of uranium, and is a black, radioactive, crystalline powder that naturally occurs in the mineral uraninite. It is used in nuclear fuel rods in nuclear re ...
matrix might never be able to truly become part of an organism, it is normal to consider such particles in the lungs and digestive tract as a form of internal contamination which results in internal exposure. *
Boron neutron capture therapy Neutron capture therapy (NCT) is a type of radiotherapy for treating locally invasive malignant tumors such as primary brain tumors, recurrent cancers of the head and neck region, and cutaneous and extracutaneous melanomas. It is a two-step pro ...
(BNCT) involves injecting a
boron-10 Boron is a chemical element with the symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the ''boron group'' it has t ...
tagged chemical that preferentially binds to tumor cells. Neutrons from a
nuclear reactor A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat fr ...
are shaped by a
neutron moderator In nuclear engineering, a neutron moderator is a medium that reduces the speed of fast neutrons, ideally without capturing any, leaving them as thermal neutrons with only minimal (thermal) kinetic energy. These thermal neutrons are immensely m ...
to the neutron energy spectrum suitable for BNCT treatment. The tumor is selectively bombarded with these neutrons. The neutrons quickly slow down in the body to become low energy ''thermal neutrons''. These ''thermal neutrons'' are captured by the injected boron-10, forming excited (boron-11) which breaks down into lithium-7 and a
helium-4 Helium-4 () is a stable isotope of the element helium. It is by far the more abundant of the two naturally occurring isotopes of helium, making up about 99.99986% of the helium on Earth. Its nucleus is identical to an alpha particle, and cons ...
alpha particle Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay, but may also be prod ...
both of these produce closely spaced ionizing radiation. This concept is described as a binary system using two separate components for the therapy of cancer. Each component in itself is relatively harmless to the cells, but when combined for treatment they produce a highly cytocidal (
cytotoxic Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa''). Cell physiology Treating c ...
) effect which is lethal (within a limited range of 5-9 micrometers or approximately one cell diameter). Clinical trials, with promising results, are currently carried out in Finland and Japan. When radioactive compounds enter the human body, the effects are different from those resulting from exposure to an external radiation source. Especially in the case of alpha radiation, which normally does not penetrate the skin, the exposure can be much more damaging after ingestion or inhalation. The radiation exposure is normally expressed as a committed dose.


History

Although radiation was discovered in late 19th century, the dangers of radioactivity and of radiation were not immediately recognized. Acute effects of radiation were first observed in the use of
X-rays An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nbs ...
when German physicist
Wilhelm Röntgen Wilhelm Conrad Röntgen (; ; 27 March 184510 February 1923) was a German mechanical engineer and physicist, who, on 8 November 1895, produced and detected electromagnetic radiation in a wavelength range known as X-rays or Röntgen rays, an achie ...
intentionally subjected his fingers to X-rays in 1895. He published his observations concerning the burns that developed, though he misattributed them to ozone, a
free radical A daughter category of ''Ageing'', this category deals only with the biological aspects of ageing. Ageing Ailments of unknown cause Biogerontology Biological processes Causes of death Cellular processes Gerontology Life extension Metabo ...
produced in air by X-rays. Other free radicals produced within the body are now understood to be more important. His injuries healed later. As a field of medical sciences, radiobiology originated from
Leopold Freund Leopold Freund (April 5, 1868 – January 7, 1943) was an Austrian-Jewish radiologist, considered the founder of medical radiology and radiotherapy. Leopold Freund was born in Miskovice in Central Bohemia, then part of the Austro-Hungarian empire, ...
's 1896 demonstration of the therapeutic treatment of a hairy mole using the newly discovered form of
electromagnetic radiation In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic (EM) field, which propagate through space and carry momentum and electromagnetic radiant energy. It includes radio waves, microwaves, infrared, (visib ...
called X-rays. After irradiating frogs and insects with X-rays in early 1896, Ivan Romanovich Tarkhanov concluded that these newly discovered rays not only photograph, but also "affect the living function". At the same time, Pierre and
Marie Curie Marie Salomea Skłodowska–Curie ( , , ; born Maria Salomea Skłodowska, ; 7 November 1867 – 4 July 1934) was a Polish and naturalized-French physicist and chemist who conducted pioneering research on radioactivity. She was the fir ...
discovered the radioactive polonium and radium later used to treat
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
. The genetic effects of radiation, including the effects on cancer risk, were recognized much later. In 1927
Hermann Joseph Muller Hermann Joseph Muller (December 21, 1890 – April 5, 1967) was an American geneticist, educator, and Nobel laureate best known for his work on the physiological and genetic effects of radiation ( mutagenesis), as well as his outspoken politica ...
published research showing genetic effects, and in 1946 was awarded the
Nobel prize The Nobel Prizes ( ; sv, Nobelpriset ; no, Nobelprisen ) are five separate prizes that, according to Alfred Nobel's will of 1895, are awarded to "those who, during the preceding year, have conferred the greatest benefit to humankind." Alfr ...
for his findings. More generally, the 1930s saw attempts to develop a general model for radiobiology. Notable here was Douglas Lea, whose presentation also included an exhaustive review of some 400 supporting publications. Before the biological effects of radiation were known, many physicians and corporations had begun marketing radioactive substances as
patent medicine A patent medicine, sometimes called a proprietary medicine, is an over-the-counter (nonprescription) medicine or medicinal preparation that is typically protected and advertised by a trademark and trade name (and sometimes a patent) and claimed ...
and radioactive quackery. Examples were radium
enema An enema, also known as a clyster, is an injection of fluid into the lower bowel by way of the rectum.Cullingworth, ''A Manual of Nursing, Medical and Surgical'':155 The word enema can also refer to the liquid injected, as well as to a device ...
treatments, and radium-containing waters to be drunk as tonics.
Marie Curie Marie Salomea Skłodowska–Curie ( , , ; born Maria Salomea Skłodowska, ; 7 November 1867 – 4 July 1934) was a Polish and naturalized-French physicist and chemist who conducted pioneering research on radioactivity. She was the fir ...
spoke out against this sort of treatment, warning that the effects of radiation on the human body were not well understood. Curie later died of
aplastic anemia Aplastic anemia is a cancer in which the body fails to make blood cells in sufficient numbers. Blood cells are produced in the bone marrow by stem cells that reside there. Aplastic anemia causes a deficiency of all blood cell types: red bloo ...
caused by radiation poisoning. Eben Byers, a famous American socialite, died of multiple cancers (but not acute radiation syndrome) in 1932 after consuming large quantities of
radium Radium is a chemical element with the symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (rat ...
over several years; his death drew public attention to dangers of radiation. By the 1930s, after a number of cases of bone necrosis and death in enthusiasts, radium-containing medical products had nearly vanished from the market. In the United States, the experience of the so-called
Radium Girls The Radium Girls were female factory workers who contracted radiation poisoning from painting watch dials with self-luminous paint. The incidents occurred at three different factories: one in Orange, New Jersey, beginning around 1917; one in O ...
, where thousands of radium-dial painters contracted oral cancers— but no cases of acute radiation syndrome— popularized the warnings of occupational health associated with radiation hazards. Robley D. Evans, at MIT, developed the first standard for permissible body burden of
radium Radium is a chemical element with the symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (rat ...
, a key step in the establishment of
nuclear medicine Nuclear medicine or nucleology is a medical specialty involving the application of radioactive substances in the diagnosis and treatment of disease. Nuclear imaging, in a sense, is " radiology done inside out" because it records radiation emi ...
as a field of study. With the development of
nuclear reactor A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat fr ...
s and
nuclear weapon A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bomb ...
s in the 1940s, heightened scientific attention was given to the study of all manner of radiation effects. The
atomic bombings of Hiroshima and Nagasaki The United States detonated two atomic bombs over the Japanese cities of Hiroshima and Nagasaki on 6 and 9 August 1945, respectively. The two bombings killed between 129,000 and 226,000 people, most of whom were civilians, and remain the onl ...
resulted in a large number of incidents of radiation poisoning, allowing for greater insight into its symptoms and dangers. Red Cross Hospital surgeon Dr. Terufumi Sasaki led intensive research into the Syndrome in the weeks and months following the Hiroshima bombings. Sasaki and his team were able to monitor the effects of radiation in patients of varying proximities to the blast itself, leading to the establishment of three recorded stages of the syndrome. Within 25–30 days of the explosion, the Red Cross surgeon noticed a sharp drop in white blood cell count and established this drop, along with symptoms of fever, as prognostic standards for Acute Radiation Syndrome. Actress
Midori Naka Midori Naka (Japanese: 仲みどり) (19 June 1909 – 24 August 1945) was a Japanese stage actress of the Shingeki style. She initially survived the atomic bombing of Hiroshima on 6 August 1945, but died 18 days later. She was the first pers ...
, who was present during the atomic bombing of Hiroshima, was the first incident of radiation poisoning to be extensively studied. Her death on August 24, 1945, was the first death ever to be officially certified as a result of radiation poisoning (or "atomic bomb disease"). The Atomic Bomb Casualty Commission and the
Radiation Effects Research Foundation The Radiation Effects Research Foundation (RERF) is a joint U.S.-Japan research organization responsible for studying the medical effects of radiation and associated diseases in humans for the welfare of the survivors and all humankind.Introduction ...
have been monitoring the health status of the survivors and their descendants since 1946. They have found that radiation exposure increases cancer risk, but also that the average lifespan of survivors was reduced by only a few months compared to those not exposed to radiation. No health effects of any sort have thus far been detected in children of the survivors.


Areas of interest

The interactions between organisms and electromagnetic fields (EMF) and ionizing radiation can be studied in a number of ways: *
Radiation physics Health physics, also referred to as the science of radiation protection, is the profession devoted to protecting people and their environment from potential radiation hazards, while making it possible to enjoy the beneficial uses of radiation. He ...
* Radiation chemistry *
Molecular A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bio ...
and
cell biology Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living an ...
*
Molecular genetics Molecular genetics is a sub-field of biology that addresses how differences in the structures or expression of DNA molecules manifests as variation among organisms. Molecular genetics often applies an "investigative approach" to determine the ...
* Cell death and
apoptosis Apoptosis (from grc, ἀπόπτωσις, apóptōsis, 'falling off') is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes ( morphology) and death. These changes in ...
* High and low-level electromagnetic radiation and health * Specific absorption rates of organisms * Radiation poisoning * Radiation oncology (
radiation therapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Rad ...
in
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
) * Bioelectromagnetics *
Electric field An electric field (sometimes E-field) is the physical field that surrounds electrically charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. It also refers to the physical field ...
and
Magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...
- their general nature. *
Electrophysiology Electrophysiology (from Greek , ''ēlektron'', "amber" etymology of "electron"">Electron#Etymology">etymology of "electron" , ''physis'', "nature, origin"; and , ''-logia'') is the branch of physiology that studies the electrical properties of bi ...
- the scientific study of the electrical properties of biological cells and tissues. *
Biomagnetism Biomagnetism is the phenomenon of magnetic fields ''produced'' by living organisms; it is a subset of bioelectromagnetism. In contrast, organisms' use of magnetism in navigation is magnetoception and the study of the magnetic fields' ''effects'' ...
- the magnetic properties of living systems (see, for example, the research of David Cohen using
SQUID True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fittin ...
imaging) and Magnetobiology - the study of effect of magnets upon living systems. See also Electromagnetic radiation and health * Bioelectromagnetism - the electromagnetic properties of living systems and Bioelectromagnetics - the study of the effect of electromagnetic fields on living systems. *
Electrotherapy Electrotherapy is the use of electrical energy as a medical treatment. In medicine, the term ''electrotherapy'' can apply to a variety of treatments, including the use of electrical devices such as deep brain stimulators for neurological dis ...
*
Radiation therapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Rad ...
* Radiogenomics *
Transcranial magnetic stimulation Transcranial magnetic stimulation (TMS) is a noninvasive form of brain stimulation in which a changing magnetic field is used to induce an electric current at a specific area of the brain through electromagnetic induction. An electric pulse gener ...
- a powerful electric current produces a transient, spatially focussed magnetic field that can penetrate the scalp and skull of a subject and induce electrical activity in the neurons on the surface of the brain. *
Magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio wave ...
- a very powerful magnetic field is used to obtain a 3D image of the density of water molecules of the brain, revealing different anatomical structures. A related technique,
functional magnetic resonance imaging Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area o ...
, reveals the pattern of blood flow in the brain and can show which parts of the brain are involved in a particular task. *
Embryogenesis An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...
,
Ontogeny Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the s ...
and
Developmental biology Developmental biology is the study of the process by which animals and plants grow and develop. Developmental biology also encompasses the biology of regeneration, asexual reproduction, metamorphosis, and the growth and differentiation of st ...
- a discipline that has given rise to many scientific field theories. *
Bioenergetics Bioenergetics is a field in biochemistry and cell biology that concerns energy flow through living systems. This is an active area of biological research that includes the study of the transformation of energy in living organisms and the study of ...
- the study of energy exchange on the molecular level of living systems. *
Biological psychiatry Biological psychiatry or biopsychiatry is an approach to psychiatry that aims to understand mental disorder in terms of the biological function of the nervous system. It is interdisciplinary in its approach and draws on sciences such as neuroscie ...
,
Neurology Neurology (from el, νεῦρον (neûron), "string, nerve" and the suffix -logia, "study of") is the branch of medicine dealing with the diagnosis and treatment of all categories of conditions and disease involving the brain, the spinal ...
,
Psychoneuroimmunology Psychoneuroimmunology (PNI), also referred to as psychoendoneuroimmunology (PENI) or psychoneuroendocrinoimmunology (PNEI), is the study of the interaction between psychological processes and the nervous and immune systems of the human body. It is ...
The activity of biological and astronomical systems inevitably generates magnetic and electrical fields, which can be measured with sensitive instruments and which have at times been suggested as a basis for "
esoteric Western esotericism, also known as esotericism, esoterism, and sometimes the Western mystery tradition, is a term scholars use to categorise a wide range of loosely related ideas and movements that developed within Western society. These ideas ...
" ideas of energy.


Radiation sources for experimental radiobiology

Radiobiology experiments typically make use of a radiation source which could be: * An isotopic source, typically 137Cs or 60Co. * A
particle accelerator A particle accelerator is a machine that uses electromagnetic fields to propel charged particles to very high speeds and energies, and to contain them in well-defined beams. Large accelerators are used for fundamental research in particle ...
generating high energy
protons A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron m ...
,
electrons The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have n ...
or charged ions. Biological samples can be irradiated using either a broad, uniform beam, or using a microbeam, focused down to cellular or subcellular sizes. * A
UV lamp Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30  PHz) to 400 nm (750  THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...
.


See also

*
Biological effects of radiation on the epigenome Ionizing radiation can cause biological effects which are passed on to offspring through the epigenome. The effects of radiation on cells has been found to be dependent on the dosage of the radiation, the location of the cell in regards to tissue ...
* Cell survival curve *
Health threat from cosmic rays Health threats from cosmic rays are the dangers posed by cosmic rays to astronauts on interplanetary missions or any missions that venture through the Van-Allen Belts or outside the Earth's magnetosphere. They are one of the greatest barriers s ...
*
NASA Space Radiation Laboratory The NASA Space Radiation Laboratory (NSRL, previously called Booster Applications Facility), is a heavy ion beamline research facility; part of the Collider-Accelerator Department of Brookhaven National Laboratory, located in Upton, New York on Lo ...
* Radioactivity in biology *
Radiology Radiology ( ) is the medical discipline that uses medical imaging to diagnose diseases and guide their treatment, within the bodies of humans and other animals. It began with radiography (which is why its name has a root referring to radiat ...
* Radiophobia *
Radiosensitivity Radiosensitivity is the relative susceptibility of cells, tissues, organs or organisms to the harmful effect of ionizing radiation. Cells types affected Cells are least sensitive when in the S phase, then the G1 phase, then the G2 phase, and ...


References


Sources

* ICRP, 2007
The 2007 Recommendations of the International Commission on Radiological Protection
ICRP Publication 103. Ann. ICRP 37 (2-4).


Further reading

*Eric Hall, ''Radiobiology for the Radiologist''. 2006. Lippincott *G.Gordon Steel, "Basic Clinical Radiobiology". 2002. Hodder Arnold. *The Institute for Radiation Biology at the Helmholtz-Center for Environmental Healt

{{Authority control Radiobiology, * Medical physics