Radiation hazard symbol.

Ionizing radiation hazard symbol (recently introduced). ^[1]

Ionizing radiation consists of highly-energetic particles or waves that can detach (ionize) at least one electron from an atom or molecule. Particle radiation is the radiation of Energy by means of fast-moving Subatomic particles. Electromagnetic radiation takes the form of self-propagating Waves in a Vacuum or in Matter. Ionization is the physical process of converting an Atom or Molecule into an Ion by adding or removing charged particles such as Electrons History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by Ionizing ability depends on the energy of individual particles or waves, and not on their number. A large flood of particles or waves will not, in the most common situations, cause ionization if the individual particles or waves are not by themselves ionizing.

Examples of ionizing radiation are energetic beta particles, neutrons, and alpha particles. Beta particles are high-energy high-speed Electrons or Positrons emitted by certain types of Radioactive nuclei such as Potassium -40 This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. Alpha particles (named after and denoted by the first letter in the Greek alphabet, α consist of two Protons and two Neutrons bound together into a The ability of light waves (photons) to ionize an atom or molecule varies across the electromagnetic spectrum. In Physics, the photon is the Elementary particle responsible for electromagnetic phenomena The electromagnetic (EM spectrum is the range of all possible Electromagnetic radiation frequencies X-rays and gamma rays can ionize almost any molecule or atom; far ultraviolet light can ionize many atoms and molecules; near ultraviolet and visible light are ionizing to very few molecules; microwaves and radio waves are non-ionizing radiation. X-radiation (composed of X-rays) is a form of Electromagnetic radiation. Gamma rays (denoted as &gamma) are a form of Electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays Microwaves are electromagnetic waves with Wavelengths ranging from 1 mm to 1 m or frequencies between 0 Radio waves are electromagnetic waves occurring on the Radio frequency portion of the Electromagnetic spectrum. Non-ionizing radiation (or esp in British English, non-ionising radiation) refers to any type of Electromagnetic radiation that does not carry enough Visible light is so ubiquitous that molecules that are ionized by it often react nearly spontaneously unless protected by materials that block the visible spectrum. Photosensitivity is the amount to which an object reacts upon receiving Photons especially Visible light. Examples include photographic film and some molecules involved in photosynthesis. Photosynthesis is a Metabolic pathway that converts Light Energy into Chemical energy.

Ionizing radiation has many practical uses in medicine, research, construction, and other areas, but presents a health hazard if used improperly. If enough ionizations occur in a biological system, they can be destructive, by such means as causing DNA damage in individual cells. DNA repair refers to a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its Genome. Extensive doses of ionizing radiation have been shown to have a mutating effect on the victim's descendants. In biology mutations are changes to the Nucleotide sequence of the Genetic material of an organism Both helpful and harmful aspects of ionizing radiation are discussed below.

Types of radiation

Alpha (α) radiation consists of Helium-4 (⁴He) nuclei and is stopped by a sheet of paper. Helium-4 ( or) is a non- Radioactive and light Isotope of Helium. Helium-4 ( or) is a non- Radioactive and light Isotope of Helium. Beta (β) radiation, consisting of electrons, is halted by an aluminium plate. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J Gamma (γ) radiation, consisting of energetic photons, is eventually absorbed as it penetrates a dense material. In Physics, the photon is the Elementary particle responsible for electromagnetic phenomena

Ionizing radiation is produced by radioactive decay, nuclear fission and nuclear fusion, by extremely hot objects (e. Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. Nuclear fission is the splitting of the nucleus of an atom into parts (lighter nuclei) often producing Free neutrons and other smaller nuclei which may In Physics and Nuclear chemistry, nuclear fusion is the process by which multiple- like charged atomic nuclei join together to form a heavier nucleus g. , the Sun produces far-ultraviolet light), and by particle accelerators that may produce, for example, fast electrons or protons or bremsstrahlung or synchrotron radiation. Bremsstrahlung ( pronounced, from German de ''bremsen'' "to brake" and de ''Strahlung'' "radiation" i This article concerns the physical phenomenon of synchrotron radiation

In order for a particle to be ionizing, it must both have a high enough energy and interact with the atoms of a target. Photons interact strongly with charged particles, so photons of sufficiently high energy also are ionizing. The energy at which this begins to happen with photons (light) is in the ultraviolet region of the electromagnetic spectrum; sunburn is one of the effects of ionization. Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays A sunburn is a burn to living tissue such as Skin produced by overexposure to Ultraviolet (UV radiation commonly from the Sun 's rays Charged particles such as electrons, positrons, and alpha particles also interact strongly with electrons of an atom or molecule. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J The positrons or antielectron is the Antiparticle or the Antimatter counterpart of the Electron. Alpha particles (named after and denoted by the first letter in the Greek alphabet, α consist of two Protons and two Neutrons bound together into a Neutrons, on the other hand, do not interact strongly with electrons, and so they cannot directly cause ionization by this mechanism. This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. However, fast neutrons will interact with the protons in hydrogen (in the manner of a billiard ball hitting another, sending it away with all of the first ball's energy of motion), and this mechanism produces proton radiation (fast protons). These protons are ionizing because of their strong interaction with electrons in matter. A neutron can also interact with an atomic nucleus, depending on the nucleus and the neutron's velocity; these reactions happen with fast neutrons and slow neutrons, depending on the situation. The neutron temperature, also called the neutron energy, indicates a free neutron's Kinetic energy, usually given in Electron volts The term The neutron temperature, also called the neutron energy, indicates a free neutron's Kinetic energy, usually given in Electron volts The term Neutron interactions in this manner often produce radioactive nuclei, which produce ionizing radiation when they decay. Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation.

In the picture at left, gamma rays are represented by wavy lines, charged particles and neutrons by straight lines. The little circles show where ionization processes occur.

An ionization event normally produces a positive atomic ion and an electron. High-energy beta particles may produce bremsstrahlung when passing through matter, or secondary electrons (δ-electrons); both can ionize in turn. Bremsstrahlung ( pronounced, from German de ''bremsen'' "to brake" and de ''Strahlung'' "radiation" i

Unlike alpha or beta particles (see particle radiation), gamma rays do not ionize all along their path, but rather interact with matter in one of three ways: the photoelectric effect, the Compton effect, and pair production. Particle radiation is the radiation of Energy by means of fast-moving Subatomic particles. Introduction When a Metallic surface is exposed to Electromagnetic radiation above a certain threshold Frequency, the light is absorbed and Electrons The Compton shift formula Klein-Nishina formulaCompton used a combination of three fundamental formulas representing the various aspects of classical and modern physics combining See also Electron-positron annihilation Meitner–Hupfeld effect Pair instability supernova By way of example, the figure shows Compton effect: two Compton scatterings that happen sequentially. In every scattering event, the gamma ray transfers energy to an electron, and it continues on its path in a different direction and with reduced energy.

In the same figure, the neutron collides with a proton of the target material, and then becomes a fast recoil proton that ionizes in turn. At the end of its path, the neutron is captured by a nucleus in an (n,γ)-reaction that leads to a neutron capture photon. Neutron capture is a kind of Nuclear reaction in which an Atomic nucleus collides with one or more Neutrons and they merge to form a heavier nucleus

The negatively-charged electrons and positively charged ions created by ionizing radiation may cause damage in living tissue. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge If the dose is sufficient, the effect may be seen almost immediately, in the form of radiation poisoning. Radiation poisoning, also called " radiation sickness " or a " creeping dose " is a form of damage to organ tissue due to excessive exposure to Lower doses may cause cancer or other long-term problems. Cancer (medical term Malignant Neoplasm) is a class of Diseases in which a group of cells display uncontrolled The effect of the very low doses encountered in normal circumstances (from both natural and artificial sources, like cosmic rays, medical X-rays and nuclear power plants) is a subject of current debate. A 2005 report released by the National Research Council (the BEIR VII report, summarized in [2]) indicated that the overall cancer risk associated with background sources of radiation was relatively low. Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar.

Radioactive materials usually release alpha particles, which are the nuclei of helium, beta particles, which are quickly moving electrons or positrons, or gamma rays. Alpha particles (named after and denoted by the first letter in the Greek alphabet, α consist of two Protons and two Neutrons bound together into a Helium ( He) is a colorless odorless tasteless non-toxic Inert Monatomic Chemical Beta particles are high-energy high-speed Electrons or Positrons emitted by certain types of Radioactive nuclei such as Potassium -40 The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J The positrons or antielectron is the Antiparticle or the Antimatter counterpart of the Electron. Gamma rays (denoted as &gamma) are a form of Electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions Alpha and beta particles can often be stopped by a piece of paper or a sheet of aluminium, respectively. Paper is thin material mainly used for writing upon printing upon or packaging WikipediaManual of Style#National varieties of English --> Aluminium foil (known They cause most damage when they are emitted inside the human body. Gamma rays are less ionizing than either alpha or beta particles, and protection against gammas requires thicker shielding. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge The damage they produce is similar to that caused by X-rays, and include burns and also cancer, through mutations. X-radiation (composed of X-rays) is a form of Electromagnetic radiation. Cancer (medical term Malignant Neoplasm) is a class of Diseases in which a group of cells display uncontrolled In biology mutations are changes to the Nucleotide sequence of the Genetic material of an organism Human biology resists germline mutation by either correcting the changes in the DNA or inducing apoptosis in the mutated cell. Human biology is an Interdisciplinary Academic field of Biology, Biological anthropology, Nutrition and Medicine which A Germline Mutation is any detectable and heritable variation in the lineage of germ cells. Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known

Non-ionizing radiation is thought to be essentially harmless below the levels that cause heating. Ionizing radiation is dangerous in direct exposure, although the degree of danger is a subject of debate. Humans and animals can also be exposed to ionizing radiation internally: if radioactive isotopes are present in the environment, they may be taken into the body. For example, radioactive iodine is treated as normal iodine by the body and used by the thyroid; its accumulation there often leads to thyroid cancer. Iodine (ˈaɪədaɪn ˈaɪədɪn or /ˈaɪədiːn/ from ιώδης iodes "violet" is a Chemical element that has the symbol I and Atomic The thyroid is one of the largest Endocrine glands in the body Cancer (medical term Malignant Neoplasm) is a class of Diseases in which a group of cells display uncontrolled Some radioactive elements also bioaccumulate. Bioaccumulation occurs when an organism absorbs a toxic substance at a rate greater than that at ftudruinsubstance is lost

Uses of ionizing radiation

Ionizing radiation has many uses, such as to kill cancerous cells. However, although ionizing radiation has many applications, overuse can be hazardous to human health. For example, at one time, assistants in shoe shops used X-rays to check a child's shoe size, but this practice was halted when it was discovered that ionizing radiation was dangerous. Shoe-fitting Fluoroscopes were X-ray machines installed in Shoe stores from the early 20th century up until about 1960 in the United States by

Technical uses of ionizing radiation

Since ionizing radiations can penetrate matter, they are used for a variety of measuring methods.

Radiography by means of gamma or X rays

This is a method used in industrial production. The piece to be radiographed is placed between the source and a photographic film in a cassette. After a certain exposure time, the film is developed and it shows internal defects of the material if there are any.

Gauges

Gauges use the exponential absorption law of gamma rays

• Level indicators: Source and detector are placed at opposite sides of a container, indicating the presence or absence of material in the horizontal radiation path. Beta or gamma sources are used, depending on the thickness and the density of the material to be measured. The method is used for containers of liquids or of grainy substances
• Thickness gauges: if the material is of constant density, the signal measured by the radiation detector depends on the thickness of the material. This is useful for continuous production, like of paper, rubber, etc.

Applications using ionization of gases by radiation

• To avoid the build-up of static electricity in production of paper, plastics, synthetic textiles, etc. , a ribbon-shaped source of the alpha emitter ²⁴¹Am can be placed close to the material at the end of the production line. The source ionizes the air to remove electric charges on the material.
• Smoke detector: Two ionisation chambers are placed next to each other. A smoke detector is a device that detects Smoke and issues an Alarm. Both contain a small source of ²⁴¹Am that gives rise to a small constant current. One is closed and serves for comparison, the other is open to ambient air; it has a gridded electrode. When smoke enters the open chamber, the current is disrupted as the smoke particles attach to the charged ions and restore them to a neutral electrical state. This reduces the current in the open chamber. When the current drops below a certain threshold, the alarm is triggered.
• Radioactive tracers for industry: Since radioactive isotopes behave, chemically, mostly like the inactive element, the behavior of a certain chemical substance can be followed by tracing the radioactivity. A radioactive tracer, also called a radioactive label, is a substance containing a Radioisotope (which is an isotope that has an unstable nucleus and that stabalizes Examples:
  • Adding a gamma tracer to a gas or liquid in a closed system makes it possible to find a hole in a tube.
  • Adding a tracer to the surface of the component of a motor makes it possible to measure wear by measuring the activity of the lubricating oil.

Biological and medical applications of ionizing radiation

In biology, radiation is mainly used for sterilization, and enhancing mutations. Foundations of modern biology There are five unifying principles Sterilization (or sterilisation, see spelling differences) refers to any process that effectively kills or eliminates transmissible agents (such as Fungi In biology mutations are changes to the Nucleotide sequence of the Genetic material of an organism For example, mutations may be induced by radiation to produce new or improved species. A very promising field is the sterile insect technique, where male insects are sterilized and liberated in the chosen field, so that they have no descendants, and the population is reduced. Sterile insect technique is a method of Biological control, whereby millions of sterile Insects are released

Radiation is also useful in sterilizing medical hardware or food. Food irradiation is the process of exposing food to Ionizing radiation in order to destroy Microorganisms Bacteria, Viruses or Insects The advantage for medical hardware is that the object may be sealed in plastic before sterilization. For food, there are strict regulations to prevent the occurrence of induced radioactivity. Induced radioactivity is when a previously stable material has been made Radioactive by exposure to specific Radiation. The growth of a seedling may be enhanced by radiation, but excessive radiation will hinder growth.

Electrons, x rays, gamma rays or atomic ions may be used in radiation therapy to treat malignant tumors (cancer). An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Radiation therapy (or radiotherapy) is the medical use of Ionizing radiation as part of Cancer treatment to control Malignant Cancer (medical term Malignant Neoplasm) is a class of Diseases in which a group of cells display uncontrolled

Tracer methods are used in nuclear medicine in a way analogous to the technical uses mentioned above. Nuclear medicine is a branch of Medicine and Medical imaging that uses the nuclear properties of matter in diagnosis and therapy

Natural background radiation

Natural background radiation comes from four primary sources: cosmic radiation, solar radiation, external terrestrial sources, and radon. Background radiation is the Ionizing radiation emitted from a variety of natural and artificial Radiation sources Radon (ˈreɪdɒn is the Chemical element that has the symbol Rn and Atomic number 86

Cosmic radiation

For more details on cosmic radiation, see Cosmic ray. For the 1962 Bruce Conner film see Cosmic Ray (film Cosmic rays are energetic particles originating from space that impinge on

The Earth, and all living things on it, are constantly bombarded by radiation from outside our solar system. This cosmic radiation consists of positively-charged ions from protons to iron nuclei. The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 The nucleus of an Atom is the very dense region consisting of Nucleons ( Protons and Neutrons, at the center of an atom The energy of this radiation can far exceed that which humans can create even in the largest particle accelerators. This radiation interacts in the atmosphere to create secondary radiation that rains down, including x-rays, muons, protons, alpha particles, pions, electrons, and neutrons. X-radiation (composed of X-rays) is a form of Electromagnetic radiation. The muon (from the letter mu (μ--used to represent it is an Elementary particle with negative Electric charge and a spin of 1/2 Alpha particles (named after and denoted by the first letter in the Greek alphabet, α consist of two Protons and two Neutrons bound together into a In Particle physics, pion (short for pi meson) is the collective name for three Subatomic particles, and. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron.

The dose from cosmic radiation is largely from muons, neutrons, and electrons, with a dose rate that varies in different parts of the world and based largely on the geomagnetic field, altitude, and solar cycle. The cosmic-radiation dose rate on airplanes is so high that, according to the United Nations UNSCEAR 2000 Report (see links at bottom), airline workers receive more dose on average than any other worker, including those in nuclear power plants.

Solar radiation

While most of the Sun's output consists of light (solar radiation), particle radiation is also produced and varies with the solar cycle. The solar cycle, or the solar magnetic activity cycle, is the main source of periodic variation of all solar phenomena driving variations in Space weather. These particles are mostly protons with relatively low energies (10-100 keV). The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive Their average composition is similar to that of the Sun itself. This represents significantly lower energy particles than come from cosmic rays. Solar particles vary widely in their intensity and spectrum, increasing in strength after some solar events such as solar flares. A solar flare is a violent explosion in a star's (like the Sun 's atmosphere releasing as much Energy as 6 × 1025 Joules Solar flares Further, an increase in the intensity of solar cosmic rays is often followed by a decrease in the galactic cosmic rays, called a Forbush decrease after their discoverer, the physicist Scott Forbush. A Forbush decrease is a rapid decrease in the observed Galactic cosmic ray intensity following a Coronal mass ejection (CME These decreases are due to the solar wind which carries the Sun's magnetic field out further to shield the earth more thoroughly from cosmic radiation. The solar wind is a Stream of charged particles&mdasha plasma &mdashthat are ejected from the upper atmosphere of the Sun.

The ionizing component of solar radiation is negligible relative to other forms of radiation on Earth's surface.

External terrestrial sources

Most materials on Earth contain some radioactive atoms, even if in small quantities. Most of the terrestrial non-radon-dose one receives from these sources is from gamma-ray emitters in the walls and floors when inside a house, or rocks and soil when outside. The major radionuclides of concern for terrestrial radiation are potassium, uranium, and thorium. A radionuclide is an Atom with an unstable nucleus, which is a nucleus characterized by excess energy which is available to be imparted either to a newly-created Potassium (pəˈtæsiəm is a Chemical element. It has the symbol K (kalium from qalīy Atomic number 19 and Atomic mass 39 Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the Thorium (ˈθɔːriəm is a Chemical element with the symbol Th and Atomic number 90 Each of these sources has been decreasing in activity since the birth of the Earth so that our present dose from potassium-40 is about ½ what it would have been at the dawn of life on Earth.

Radon

Radon-222 is produced by the decay of radium-226 which is present wherever uranium is found. Radon (ˈreɪdɒn is the Chemical element that has the symbol Rn and Atomic number 86 Radium (ˈreɪdiəm is a radioactive Chemical element which has the symbol Ra and Atomic number 88 Since radon is a gas, it seeps out of uranium-containing soils found across most of the world and may accumulate in well-sealed homes. It is often the single largest contributor to an individual's background radiation dose and is certainly the most variable from location to location. Radon gas could be the second largest cause of lung cancer in America, after smoking. Smoking is a practice where a substance most commonly Tobacco, is burned and the Smoke tasted or inhaled ^[2]

Human-made radiation sources

Natural and artificial radiation sources are similar in their effects on matter. Above the background level of radiation exposure, the U. S. Nuclear Regulatory Commission (NRC) requires that its licensees limit human-made radiation exposure for individual members of the public to 100 mrem (1 mSv) per year, and limit occupational radiation exposure to adults working with radioactive material to 5,000 mrem (50 mSv) per year. Nuclear Regulatory Commission (or NRC) is a United States government agency that was established by the Energy Reorganization Act in 1974 and was first The Röntgen ( roentgen) equivalent in man or rem (symbol rem) The sievert (symbol Sv is the SI derived unit of dose equivalent.

The average exposure for Americans is about 360 mrem (3. 6 mSv) per year, 81 percent of which comes from natural sources of radiation. The remaining 19 percent results from exposure to human-made radiation sources such as medical X-rays, most of which is deposited in people who have CAT scans. Computed tomography (CT is a Medical imaging method employing Tomography. This compares with the average dose received by people in the UK of about 2. 2 mSv. As already mentioned, an important source of natural radiation is radon gas, which seeps continuously from bedrock but can, because of its high density, accumulate in poorly ventilated houses. Radon (ˈreɪdɒn is the Chemical element that has the symbol Rn and Atomic number 86

The background rate for radiation varies considerably with location, being as low as 1. 5 mSv/a (1. 5 mSv per year) in some areas and over 100 mSv/a in others. People in some parts of Ramsar, a city in northern Iran, receive an annual absorbed dose from background radiation that is up to 260 mSv/a. Ramsar (in Persian: رامسر is a town in the Mazandaran province of Iran, on the coast of the Caspian Sea. For a topic outline on this subject see List of basic Iran topics. Despite having lived for many generations in these high background areas, inhabitants of Ramsar show no significant cytogenetic differences compared to people in normal background areas. This has led to the suggestion that high but steady levels of radiation are easier for humans to sustain than sudden radiation bursts.

Some human-made radiation sources affect the body through direct radiation, while others take the form of radioactive contamination and irradiate the body from within. Radioactive contamination is the uncontrolled distribution of radioactive material in a given environment Irradiation is the process by which an item is exposed to Radiation.

Medical procedures, such as diagnostic X-rays, nuclear medicine, and radiation therapy are by far the most significant source of human-made radiation exposure to the general public. X-radiation (composed of X-rays) is a form of Electromagnetic radiation. Nuclear medicine is a branch of Medicine and Medical imaging that uses the nuclear properties of matter in diagnosis and therapy Radiation therapy (or radiotherapy) is the medical use of Ionizing radiation as part of Cancer treatment to control Malignant Some of the major radionuclides used are I-131, Tc-99, Co-60, Ir-192, and Cs-137. A radionuclide is an Atom with an unstable nucleus, which is a nucleus characterized by excess energy which is available to be imparted either to a newly-created Iodine (ˈaɪədaɪn ˈaɪədɪn or /ˈaɪədiːn/ from ιώδης iodes "violet" is a Chemical element that has the symbol I and Atomic Technetium (tɛkˈniːʃɪəm is the lightest Chemical element with no Stable isotope. Cobalt (ˈkoʊbɒlt is a hard lustrous silver-grey Metal, a Chemical element with symbol Co. Iridium (ɪˈrɪdiəm is a Chemical element that has the symbol Ir and Atomic number 77 Caesium or cesium (ˈsiːziəm is the Chemical element with the symbol Cs and Atomic number 55 These are rarely released into the environment. The public also is exposed to radiation from consumer products, such as tobacco (polonium-210), building materials, combustible fuels (gas, coal, etc. Tobacco is an Agricultural product recognized as an addictive drug processed from the fresh Leaves of plants in the genus Nicotiana. Polonium (pəˈloʊniəm is a Chemical element with the symbol Po and Atomic number 84 discovered in 1898 by Marie and Pierre Curie ), ophthalmic glass, televisions, luminous watches and dials (tritium), airport X-ray systems, smoke detectors (americium), road construction materials, electron tubes, fluorescent lamp starters, and lantern mantles (thorium). Glass in the common sense refers to a Hard, Brittle, transparent Solid, such as that used for Windows many Television ( TV) is a widely used Telecommunication medium for sending ( Broadcasting) and receiving moving Images, either monochromatic A watch is a timepiece that is made to be worn on a person The term now usually refers to a wristwatch, which is worn on the wrist with a strap or Bracelet. Tritium (ˈtɹɪtiəm symbol or, also known as Hydrogen-3) is a radioactive Isotope of Hydrogen. X-radiation (composed of X-rays) is a form of Electromagnetic radiation. A smoke detector is a device that detects Smoke and issues an Alarm. Americium (ˌæməˈrɪsiəm is a Synthetic element that has the symbol Am and Atomic number 95 A fluorescent lamp or fluorescent tube is a Gas-discharge lamp that uses Electricity to excite mercury Vapor. A lantern is a Portable Lighting device used to illuminate broad areas Thorium (ˈθɔːriəm is a Chemical element with the symbol Th and Atomic number 90

Of lesser magnitude, members of the public are exposed to radiation from the nuclear fuel cycle, which includes the entire sequence from mining and milling of uranium to the disposal of the spent fuel. Nuclear fuel is any material that can be consumed to derive Nuclear energy, by analogy to chemical Fuel that is burned to derive energy Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the The effects of such exposure have not been reliably measured due to the extremely low doses involved. Estimates of exposure are low enough that proponents of nuclear power liken them to the mutagenic power of wearing trousers for two extra minutes per year (because heat causes mutation). Opponents use a cancer per dose model to assert that such activities cause several hundred cases of cancer per year.

In a nuclear war, gamma rays from fallout of nuclear weapons would probably cause the largest number of casualties. Gamma rays (denoted as &gamma) are a form of Electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions Fallout is the residual radiation hazard from a Nuclear explosion, so named because it "falls out" of the atmosphere into which it is spread during the explosion A nuclear weapon is an explosive device that derives its destructive force from Nuclear reactions either fission or a combination of fission and fusion. Immediately downwind of targets, doses would exceed 300 Gy per hour. The gray (symbol Gy is the SI unit of absorbed radiation dose. As a reference, 4. 5 Gy (around 15,000 times the average annual background rate) is fatal to half of a normal population, without medical treatment.

Occupationally exposed individuals are exposed according to the sources with which they work. The radiation exposure of these individuals is carefully monitored with the use of pocket-pen-sized instruments called dosimeters. A dosimeter is any device used to measure an individual's exposure to a hazardous environment particularly when the hazard is cumulative over long intervals of Time

Some of the radionuclides of concern include cobalt-60, caesium-137, americium-241, and iodine-131. Cobalt (ˈkoʊbɒlt is a hard lustrous silver-grey Metal, a Chemical element with symbol Co. Caesium or cesium (ˈsiːziəm is the Chemical element with the symbol Cs and Atomic number 55 Americium (ˌæməˈrɪsiəm is a Synthetic element that has the symbol Am and Atomic number 95 Iodine (ˈaɪədaɪn ˈaɪədɪn or /ˈaɪədiːn/ from ιώδης iodes "violet" is a Chemical element that has the symbol I and Atomic Examples of industries where occupational exposure is a concern include:

• Airline crew (the most exposed population)
• Fuel cycle
• Industrial radiography
• Nuclear medicine and medical radiology departments (including nuclear oncology)
• Nuclear power plants (during maintenance work near the reactor core)
• Research laboratories (government, university and private)

Biological effects of ionizing radiation

The biological effects of radiation are thought of in terms of their effects on living cells. The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called For low levels of radiation, the biological effects are so small they may not be detected in epidemiological studies. The body repairs many types of radiation and chemical damage. Biological effects of radiation on living cells may result in a variety of outcomes, including:

1. Cells experience DNA damage and are able to detect and repair the damage.
2. Cells experience DNA damage and are unable to repair the damage. These cells may go through the process of programmed cell death, or apoptosis, thus eliminating the potential genetic damage from the larger tissue.
3. Cells experience a nonlethal DNA mutation that is passed on to subsequent cell divisions. This mutation may contribute to the formation of a cancer.

Other observations at the tissue level are more complicated. These include:

1. In some cases, a small radiation dose reduces the impact of a subsequent, larger radiation dose. This has been termed an 'adaptive response' and is related to hypothetical mechanisms of hormesis. Radiation hormesis (also called Radiation homeostasis) is the Hypothesis that chronic low doses of Ionizing radiation are beneficial stimulating repair

Hormesis

Main article: Radiation hormesis

Radiation hormesis is the unproven theory that a low level of ionizing radiation (i. Radiation hormesis (also called Radiation homeostasis) is the Hypothesis that chronic low doses of Ionizing radiation are beneficial stimulating repair e. near the level of Earth's natural background radiation) helps "immunize" cells against DNA damage from other causes (such as free radicals or larger doses of ionizing radiation), and decreases the risk of cancer. The theory proposes that such low levels activate the body's DNA repair mechanisms, causing higher levels of cellular DNA-repair proteins to be present in the body, improving the body's ability to repair DNA damage. This assertion is very difficult to prove (using, for example, statistical cancer studies) because the effects of very low ionizing radiation levels are too small to be statistically measured amid the "noise" of normal cancer rates.

Therefore, the idea of radiation hormesis is considered unproven by regulatory bodies, which generally use the standard "linear, no threshold" (LNT) model, which states that risk of cancer is directly proportional to the dose level of ionizing radiation. The linear no-threshold model ( LNT) is a model of the damage caused by Ionizing radiation which presupposes that the response is Linear (i The LNT model is safer for regulatory purposes because it assumes worst-case damage due to ionizing radiation; therefore, if regulations are based on it, workers might be over-protected, but they will never be under-protected.

At high ionizing radiation levels, such as the acute doses received near the Hiroshima and Nagasaki bomb blasts, the risk of cancer does increase roughly linearly with dose, which is the origin of the LNT model. Thus, there is a consensus that the LNT method should continue to be used because it is safer from a regulatory perspective and because the effects of very low radiation doses are too small to be measured statistically. See the National Academies Press book. ^[3].

Chronic radiation exposure

Exposure to ionizing radiation over an extended period of time is called chronic exposure. The natural background radiation is chronic exposure, but a normal level is difficult to determine due to variations. Geographic location and occupation often affect chronic exposure.

Acute radiation exposure

Acute radiation exposure is an exposure to ionizing radiation which occurs during a short period of time. There are routine brief exposures, and the boundary at which it becomes significant is difficult to identify. Extreme examples include

• Instantaneous flashes from nuclear explosions.
• Exposures of minutes to hours during handling of highly radioactive sources.
• Laboratory and manufacturing accidents.
• Intentional and accidental high medical doses.

The effects of acute events are more easily studied than those of chronic exposure. Chronic exposure is reactant.

Radiation levels

The associations between ionizing radiation exposure and the development of cancer are mostly based on populations exposed to relatively high levels of ionizing radiation, such as Japanese atomic bomb survivors, and recipients of selected diagnostic or therapeutic medical procedures. Cancer (medical term Malignant Neoplasm) is a class of Diseases in which a group of cells display uncontrolled

Cancers associated with high dose exposure include leukemia, thyroid, breast, bladder, colon, liver, lung, esophagus, ovarian, multiple myeloma, and stomach cancers. Leukemia or leukaemia (Greek leukos λευκός, "white" aima αίμα, "blood" is a Cancer of the Blood United States Department of Health and Human Services literature also suggests a possible association between ionizing radiation exposure and prostate, nasal cavity/sinuses, pharyngeal and laryngeal, and pancreatic cancer. The United States Department of Health and Human Services ( HHS) is a Cabinet department of the United States government with the goal of protecting

The period of time between radiation exposure and the detection of cancer is known as the latent period. Incubation period is the Time elapsed between exposure to a Pathogenic Organism, or Chemical or radiation, and when Symptoms Those cancers that may develop as a result of radiation exposure are indistinguishable from those that occur naturally or as a result of exposure to other chemical carcinogens. The term carcinogen refers to any substance Radionuclide or radiation that is an agent directly involved in the promotion of Cancer or in the fatation of its propagation Furthermore, National Cancer Institute literature indicates that other chemical and physical hazards and lifestyle factors, such as smoking, alcohol consumption, and diet, significantly contribute to many of these same diseases. The National Cancer Institute (NCI is part of the United States Federal government's National Institutes of Health. In Chemistry, an alcohol is any Organic compound in which a Hydroxyl group ( - O[[hydrogen H]]) is bound to a Carbon

Although radiation may cause cancer at high doses and high dose rates, public health data regarding lower levels of exposure, below about 1,000 mrem (10 mSv), are harder to interpret. Public health is "the science and art of preventing disease prolonging life and promoting health through the organised efforts and informed choices of society organisations To assess the health impacts of lower radiation doses, researchers rely on models of the process by which radiation causes cancer; several models have emerged which predict differing levels of risk.

Studies of occupational workers exposed to chronic low levels of radiation, above normal background, have provided mixed evidence regarding cancer and transgenerational effects. Cancer results, although uncertain, are consistent with estimates of risk based on atomic bomb survivors and suggest that these workers do face a small increase in the probability of developing leukemia and other cancers. One of the most recent and extensive studies of workers was published by Cardis et al. in 2005 [3].

The linear dose-response model suggests that any increase in dose, no matter how small, results in an incremental increase in risk. The linear no-threshold model (LNT) hypothesis is accepted by the Nuclear Regulatory Commission (NRC) and the EPA and its validity has been reaffirmed by a National Academy of Sciences Committee. The linear no-threshold model ( LNT) is a model of the damage caused by Ionizing radiation which presupposes that the response is Linear (i Nuclear Regulatory Commission (or NRC) is a United States government agency that was established by the Energy Reorganization Act in 1974 and was first (See the BEIR VII report, summarized in [4]. ) Under this model, about 1% of a population would develop cancer in their lifetime as a result of ionizing radiation from background levels of natural and man-made sources.

Ionizing radiation damages tissue by causing ionization, which disrupts molecules directly and also produces highly reactive free radicals, which attack nearby cells. In Chemistry, radicals (often referred to as free radicals) are atoms molecules or ions with Unpaired electrons on an otherwise Open shell The net effect is that biological molecules suffer local disruption; this may exceed the body's capacity to repair the damage and may also cause mutations in cells currently undergoing replication.

Two widely studied instances of large-scale exposure to high doses of ionizing radiation are: atomic bomb survivors in 1945; and emergency workers responding to the 1986 Chernobyl accident. A nuclear weapon is an explosive device that derives its destructive force from Nuclear reactions either fission or a combination of fission and fusion. Year 1945 ( MCMXLV) was a Common year starting on Monday (link will display the full calendar Year 1986 ( MCMLXXXVI) was a Common year starting on Wednesday (link displays 1986 Gregorian calendar) The Chernobyl disaster was a nuclear reactor accident in the Chernobyl Nuclear Power Plant in the Soviet Union.

Approximately 134 plant workers and fire fighters engaged at the Chernobyl power plant received high radiation doses (70,000 to 1,340,000 mrem or 700 to 13,400 mSv) and suffered from acute radiation sickness. Of these, 28 died from their radiation injuries.

Longer term effects of the Chernobyl accident have also been studied. There is a clear link (see the UNSCEAR 2000 Report, Volume 2: Effects) between the Chernobyl accident and the unusually large number, approximately 1,800, of thyroid cancers reported in contaminated areas, mostly in children. These were fatal in some cases. Other health effects of the Chernobyl accident are subject to current debate.

Ionizing radiation level examples

Recognized effects of acute radiation exposure are described in the article on radiation poisoning. Radiation poisoning, also called " radiation sickness " or a " creeping dose " is a form of damage to organ tissue due to excessive exposure to The exact units of measurement vary, but light radiation sickness begins at about 50–100 rad (0. The rad is a largely obsolete unit of absorbed Radiation dose with symbol rad. 5–1 gray (Gy), 0. The gray (symbol Gy is the SI unit of absorbed radiation dose. 5–1 Sv, 50–100 rem, 50,000–100,000 mrem). The sievert (symbol Sv is the SI derived unit of dose equivalent. The Röntgen ( roentgen) equivalent in man or rem (symbol rem)

Although the SI unit of radiation dose equivalent is the sievert, chronic radiation levels and standards are still often given in millirems, 1/1000th of a rem (1 mrem = 0. 01 mSv).

The following table includes some short-term dosages for comparison purposes.

Monitoring and controlling exposure to ionizing radiation

Radiation has always been present in the environment and in our bodies. The human body cannot sense ionizing radiation, but a range of instruments exists which are capable of detecting even very low levels of radiation from natural and man-made sources.

Dosimeters measure an absolute dose received over a period of time. A dosimeter is any device used to measure an individual's exposure to a hazardous environment particularly when the hazard is cumulative over long intervals of Time Ion-chamber dosimeters resemble pens, and can be clipped to one's clothing. Film-badge dosimeters enclose a piece of photographic film, which will become exposed as radiation passes through it. This article is mainly concerned with Still photography film For Motion picture film please see Film stock. Ion-chamber dosimeters must be periodically recharged, and the result logged. Film-badge dosimeters must be developed as photographic emulsion so the exposures can be counted and logged; once developed, they are discarded.

Geiger counters and scintillation counters measure the dose rate of ionizing radiation directly. A Geiger counter, also called a Geiger-Müller counter, is a type of Particle detector that measures Ionizing radiation. A scintillation counter measures Ionizing radiation. The Sensor, called a Scintillator, consists of a transparent Crystal, usually phosphor

There are four standard ways to limit exposure:

Time: For people who are exposed to radiation in addition to natural background radiation, limiting or minimizing the exposure time will reduce the dose from the radiation source.

Distance: Radiation intensity decreases sharply with distance, according to an inverse square law. In Physics, an inverse-square law is any Physical law stating that some physical Quantity or strength is inversely proportional

Shielding: Barriers of lead, concrete, or water give effective protection from radiation formed of energetic particles such as gamma rays and neutrons. Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly Concrete is a construction material composed of Cement (commonly Portland cement) as well as other cementitious materials such as Fly ash and Slag Gamma rays (denoted as &gamma) are a form of Electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. Some radioactive materials are stored or handled underwater or by remote control in rooms constructed of thick concrete or lined with lead. A remote control is an electronic device used for the remote operation of a Machine. There are special plastic shields which stop beta particles and air will stop alpha particles. Plastic is the general common term for a wide range of synthetic or semisynthetic organic solid materials suitable for the manufacture of industrial products Shielding can be designed using halving thicknesses, the thickness of material that reduces the radiation by half. Halving thicknesses for gamma rays are discussed in the article gamma rays. Gamma rays (denoted as &gamma) are a form of Electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions

Containment: Radioactive materials are confined in the smallest possible space and kept out of the environment. Radioactive isotopes for medical use, for example, are dispensed in closed handling facilities, while nuclear reactors operate within closed systems with multiple barriers which keep the radioactive materials contained. A radionuclide is an Atom with an unstable nucleus, which is a nucleus characterized by excess energy which is available to be imparted either to a newly-created This article is a subarticle of Nuclear power. A nuclear reactor is a device in which Nuclear chain reactions are initiated controlled Rooms have a reduced air pressure so that any leaks occur into the room and not out of it.

In a nuclear war, an effective fallout shelter reduces human exposure at least 1,000 times. A fallout shelter is an enclosed space specially designed to protect occupants from radioactive debris or fallout resulting from a Nuclear explosion. Most people can accept doses as high as 1 Gy, distributed over several months, although with increased risk of cancer later in life. Other civil defense measures can help reduce exposure of populations by reducing ingestion of isotopes and occupational exposure during war time. Civil defense or civil defence (see spelling differences) is an effort to prepare Civilians for Military attack One of these available measures could be the use of potassium iodide (KI) tablets which effectively block the uptake of dangerous radioactive iodine into the human thyroid gland. Potassium iodide is an Inorganic compound with formula K[[iodide I]] The thyroid is one of the largest Endocrine glands in the body

See also

References

External links

• The Nuclear Regulatory Commission regulates most commercial radiation sources and non-medical exposures in the US:
• Biological Effects of Low Level Exposures: Radiation Hormesis
• Health Risks from Exposure to Low Levels of Ionizing Radiation: BEIR VII Phase 2
• NLM Hazardous Substances Databank – Ionizing Radiation
• RISC-RAD is a European research project on assessment of low dose cancer risk
• UNSCEAR 2000 Report, Volume 1: Sources
• UNSCEAR 2000 Report, Volume 2: Effects
• Beginners Guide to Ionising Radiation Measurement
• Quantities, units and their relationships
• Plans for homemade ionizing radiation meter
• List of common household radioactive items
• WikiMindMap