Ionizing Radiation Ebooks Catalog
An important physical cause of toxic effects is a variety of forms of radiation. Ionizing radiation possesses enough energy to strip an electron from an atom. This can result in the formation of damaging free radicals or directly damage bonds in biochemical substances. The most sensitive system in living things is the DNA, since damage to a single molecule can transform a cell to malignancy. It is not necessary for a radioactive emission to damage a DNA molecule directly. The most abundant molecule in living things is water. Water can form free radicals when irradiated, and these in turn can produce toxic effects, including genotoxicity. Ionizing radiation may be electromagnetic (g-rays, x-rays, ultraviolet rays) or particulate. The major particulate forms of radiation are a and p, but they may include neutrons, other subatomic particles, or larger particles such as various atomic nuclei found in cosmic rays. Of primary interest here the a, p, and g emissions from the decay of...
Figure 12 Bivalve mounted on a rack positioned in front of an industrial proximity sensor. A steel washer is attached to the free-moving valve of the mussel. When the mussel moves the small electromagnetic field emitted by the proximity sensor is disturbed and based on that disturbance researchers can tell the position of the valve, that is, is it open or closed. Figure 12 Bivalve mounted on a rack positioned in front of an industrial proximity sensor. A steel washer is attached to the free-moving valve of the mussel. When the mussel moves the small electromagnetic field emitted by the proximity sensor is disturbed and based on that disturbance researchers can tell the position of the valve, that is, is it open or closed.
Where E is energy, m mass and c the velocity of electromagnetic radiation in vacuum ( 3x 10s m s '). The transformation from matter into energy and vice versa is only of interest for nuclear processes and does not need be applied to ecosystems on earth. We might therefore break the proposition down into two more useful propositions, when applied in ecology
Exposure-response functions generally increase mono-tonically and are nonlinear. Some evidence exists for certain stressors (e.g., ionizing radiation) that actually result in a positive response for very low magnitudes of exposure. This uncommon phenomenon of hormesis remains the exception to the usual sigmoid-shaped function. Depending on the nature of the stressor, the functions can exhibit a threshold magnitude of exposure required before any ecological response is observed. This value is termed a lowest observed effects concentration or LOEC. The LOEC can be used as an endpoint for comparison with exposure estimates in assessing risk. Another exposure value often used as an endpoint is the concentration (or dose) that produces 50 of the maximum response. For example, the concentration that results in 50 mortality during a prescribed period of exposure (e.g., 48, 96 h) defines the LC50 (lethal concentration that produces 50 mortality). An EC50 defines an exposure that results in a...
Ionization The formation of ions by the addition or removal of electrons from atoms, molecules, or radicals. It is a major route for the transfer of energy from electromagnetic radiation to matter. See also electromagnetic energy ionizing radiation. ionizing radiation Radiation that causes atoms or molecules to lose electrons, so forming ions. There are two main
A fascinating example for a highly specialized microorganism is Deinococcus radiodurans that contains four to ten copies of its genome in a cell and in addition has a highly efficient DNA-repair system that enables it to reassemble its genome even if it was considerably destroyed. This organism is not only very stable against desiccation and UV light but also against ionizing radiation.
Once installed, metal products cause few problems, but there can be a release of metal ions from external surfaces when washed by rain, which drain into the soil and ground water lead and copper cause the most problems, while zinc can be a problem if used in large quantities. Using a lot of metal in a building can also increase electromagnetic fields inside it.
Surface products based on non-mineral materials usually present no problems in the indoor climate. Some of the additives can entail a risk of unhealthy dust and fumes. If steel reinforcement is used, the electromagnetic fields in a building can increase. Many products can be reused if they are easy to dismantle. They are usually inert and can, if nothing else, be used as fill material. An exception is gypsum products that can degrade to polluting sulphur compounds.
Environmentally induced mutations (i.e., due to chemical exposure, ionizing radiation, or UV) can affect survival, metabolism, growth, reproduction, propensity to develop cancer, or behavior in offspring or other descendants at any life stage. If these mutations are expressed in a dominant fashion, their effects may be always apparent when a mutant allele is present. If they are recessive mutations, the mutant phenotype is apparent only in the homozygous state. Exposure to mutagenic agents may increase the mutation rate of populations, that is, the number of new mutations per generation.
The absorption of energy by atoms followed by emission of electromagnetic radiation. Phosphorescence is a type of luminescence, and is distinguished from fluorescence by the fact that the emitted radiation continues for some time after the source of excitation has been removed. In phosphorescence the excited atoms have relatively long lifetimes before they make transitions to lower energy states. However, there is no defined time distinguishing phosphorescence from fluorescence.
The EM methods use a transmitter coil to generate an electromagnetic field that induces eddy currents in the ground below the instrument. A receiver coil measures secondary electromagnetic fields created by the eddy currents and produces an output voltage that can be related to variations in subsurface conductivity as shown in Figure 9.14.1. Variations in subsurface conductivity may be caused by changes in the basic soil or rock types, thickness of the soil and rock layers, moisture content, fluid conductivity, and depth to the water table.
Environmental engineers often use the GPR methods to locate buried objects, map the depth to shallow water tables, and delineate soil horizons. The principles involved in GPR technology are similar to those in seismic refraction, except that in GPR, electromagnetic energy is used instead of acoustic energy, and the resulting image is relatively easy to interpret.
Furthermore, we are mainly concerned here with environmental pollutants. The field of toxicology also deals with other toxins, such as pharmaceuticals, food additives, and those that occur naturally. Of particular interest are xenobiotics. Various forms of radiation, if capable of depositing enough energy to break chemical bonds, can also produce toxic effects. Radiation with sufficient energy is called ionizing radiation or just high-energy radiation. Examples include ultraviolet, x-ray, and gamma radiation from the electromagnetic spectrum, and high-energy particles such as alpha or beta radiation (helium nuclei and electrons, respectively) from radioactive decay.
Ultraviolet light from the sun is a form of ionizing radiation that can cause skin cancer, or melanoma. The basal cells and melanocytes are vulnerable to UV. It is feared that the destruction of stratospheric ozone by substances such as chlorofluorocarbons will result in increased UV radiation at the ground level, leading to increased melanoma. Such an increase has already been observed in Australia, which has also experienced declines in stratospheric ozone. Physical agents Microwaves Ionizing radiation High temperatures
Toxicity is a relative measure of the ability of an agent to cause a harmful effect on a living organism. All substances have toxic properties. Even water is an irritant to the skin, and oxygen is toxic to humans at a high enough partial pressure and duration of exposure. On the other hand, some substances that are common industrial toxins are beneficial or even necessary to life at lower doses. This is particularly true with some of the metals, such as chromium or nickel. Even ionizing radiation can fit this category. Ultraviolet radiation from the sun converts 7-dehydrocholesterol in the skin into a form of vitamin D, a necessary nutrient. Figure 19.1 compares the type of response of necessary compounds with those that are not. Curve (a) represents the case in which the substance is a required nutrient curve (b) is the case for a substance that is not required. For case (a) there is a deficiency of the compound below the concentration C1, whereas it is toxic above C2. Concentration...
In addition to solar radiation reflected back to space, our planet also loses the energy via thermal emission. The emission from the Earth's surface corresponds to the emission of a blackbody at 288 K. Because the thermal emission strongly depends on temperature and Earth's temperatures are much smaller than those of the Sun, electromagnetic radiation emitted by the Earth's surface-atmosphere system occurs at the longer wavelengths, with its maximum at about 10 versus 0.5 mm for the Sun. About 99 of the radiant energy emitted by the Earth's surface and atmosphere is found in the band of 4-100 mm. This radiation is called terrestrial radiation. Other commonly used names are longwave radiation and thermal IR radiation. Emission at wavelengths larger than 100 mm is very small and practically irrelevant for the global energy budget, although it is actively used in various remote sensing applications.
Seaweeds can concentrate radioiodine with great rapidity and fish absorb a variety of radioactive substances. In addition radioactive substances can bioaccumulate in marine animals in a similar way to heavy metals. The effects on marine organisms are not fully understood but may include genetic disturbances and increased mortality both in young stages and in adults. Interestingly, many marine invertebrates can withstand radiation doses that would kill people. Some deep-water marine shrimps, exposed to doses of natural radiation sufficient to debilitate people, remain unharmed. A variety of cancers in humans, such as childhood leukaemia, is linked to radiation exposure.
Much of the inexactitude of the above reproductive toxicity assessment scheme stems from the manner in which the laboratory exposures of the test species radically differ from the actual exposures of receptors in the wild. By way of example, nearly all the laboratory studies with mammals are conducted with mice or rats, but the mammalian species that are of concern in ERAs are the larger, higher-trophic-level, and wider-ranging species, such as fox, deer, raccoon, and coyote. Aside from this key species difference, the form of the chemical tested with is rarely the one that the receptor in the wild encounters. Even in the rare case of the chemical form being the same, the chemical in the outdoors has been subjected to numerous environmental factors over the decades since the site became contaminated (temperature extremes, precipitation, photoincident light, ionizing radiation, etc.), and these have likely served to significantly alter the chemical's toxicity. The laboratory studies...
Form of direct radiation, inhalation of respirable plutonium-containing dust particles and aerosols, and deposition on the skin (Figure 1). In the lung, the size distribution of plutonium-containing particles is directly related to the radiological dose received, the retention rates, and the distribution to target organs. Furthermore, plutonium solubility in lung tissue after inhalation affects the exposure time, with less-soluble compounds (e.g., Pu-239 dioxide) being retained longer than the more soluble forms (e.g., Pu-239 nitrate). Soluble compounds, however, are more available for absorption into the cytoplasm of a cell. This decreases the distance between the ionizing radiation and sensitive cellular structures such as DNA, which results in an increased chance of mutations. With dermal contact, the penetration of plutonium through the tissue is generally slight, which limits the exposure to cells near the site of contact and reduces systemic effects. cMyers DK (1989) The general...
The Sun is a typical G2 star in the universe powered by nuclear reactions, mainly the nuclear fusion of hydrogen atoms to form helium. Because the Sun is the closest star to our planet with a mean distance of about 1.496 x 1011 m, it is the major external source of energy for the Earth. In its absence, the Earth would be a cold and lifeless planet. Solar radiation, or electromagnetic radiation emitted by the Sun, corresponds to a blackbody emission temperature of about 5780 K. According to the Stefan-Boltzmann law, the radiant energy emitted by the blackbody at temperature T is As a matter of convention, the electromagnetic spectrum is subdivided into discrete spectral bands with assigned names. The approximate wavelength boundaries and commonly used names are given in Table 1. Spanning the ultraviolet (UV), visible, and near-infrared (near-IR) bands, the region between about 0.01 and 4 mm contains practically all solar energy that is of relevance to the Earth's radiation balance....
Finally, some organisms may undergo a phenomenon known as adaptive mutagenesis. In this process, environmental stressors cause an increase in endogenous or spontaneous mutations, presumably by endogenous inhibition of repair and mismatch detection. This is thought to be an adaptive mechanism whereby bacteria create de novo genetic variation, because some of the new variants may survive the stress better than others. It is not known if adaptive mutation occurs in eukaryotes, or genotoxic stressors can also induce adaptive mutations. However, a similar process occurs in cancer cells, which gradually accumulate more and more mutations after initiation of the tumor - a process called genomic instability. Latent genomic instability can also occur in radiation-exposed cells, which may spontaneously develop high numbers of mutations long after radiation exposure and initial repair of the damage to DNA.
As it propagates through the atmosphere, solar radiation undergoes scattering and absorption by gases, aerosol, and clouds. The fraction of solar radiation that survives and reaches the surface is partly reflected back to the atmosphere. The remainder is absorbed by the surface. The scattered (or diffused) radiation can undergo many acts of scattering and reflection until it is either reflected back to the space or absorbed by the Earth's surface-atmosphere system. Absorption of solar radiation, a process by which the energy transported by electromagnetic waves is converted to other forms, is the sole significant source ofheat that ultimately supports the climate and life on our planet. Unlike absorption, scattering is a process that conserves the radiant energy but redirects the energy from the incident wave in all directions.
Detection, identification, and quantification of the specific radionuclide responsible for the presence of ionizing radiation is very often required. Identification of the radionu-clide facilitates the design of systems to safely and economically handle radioactive materials. Many different types of instruments, ranging in price from several thousand to several hundred thousand dollars, are available. Field measuring devices are often used to detect and approximate the amount of radiation present. Identification and quantification is usually performed in a controlled laboratory area, equipped to minimize background interference and gross contamination, and to ensure personnel safety.
Quite a lot ofdata have been accumulated on the influence of weak electromagnetic fields on the information exchange between living cells. Cosmic rays could in certain way influence the information exchange that is conducted by means of weak electromagnetic fields between cells of a living organism, and therefore alter functioning of the multi-cell structures.
Mechanisms of plutonium toxicity may be attributed to its chemical and or radioactive properties, although to date, no thorough distinction between the two has been made because the chemical toxicity is thought to be unimportant relative to the radiological toxicity. The toxicologically relevant decay products of plutonium isotopes are alpha emissions. This highly ionizing radiation usually causes the greatest effects in the immediate vicinity of plutonium contamination due to the short penetration distance of alpha particles. Depending on the exposure scenario, the resulting effects of the ionizing radiation include cytotoxicity and tissue necrosis (at higher doses) or genotoxicity (at lower doses), with cancer being the best documented in animal studies. In inhalation studies conducted with beagles, in order of frequency, bone, lung, and liver tumors were identified and determined to be the cause of death in many cases, with liver tumors being the least likely to result in death....
Now imagine that this system is irradiated with electromagnetic radiation such that there is a net absorption of the radiation by at least one component of the system (this is what happens during photosynthesis). The electromagnetic radiation that is absorbed will induce additional transitions between components as well as the previous radiation-independent transitions. Therefore, there is a new set of fractions and transition probabilities, fj and t'j which include both the radiation-independent and radiation-dependent transitions. Now, using our old friend proof by contradiction from Chapter 2, it can be shown that there are some pairs of components i and j for which the following does not hold Therefore in a system closed to material inputs and outputs, the absorption of photons (energy) by one component necessarily leads to at least one cycle around several components. The absorption of photons is, of course, what photosynthesis does. Eventually this electromagnetic energy must be...
Light is the visible part of the spectrum of electromagnetic radiation emanating from the sun. Electromagnetic energy occurs in indivisible units, called quanta, that travel along sinusoidal trajectories, at a velocity (in air) of c 3 x 108 m s-1. The wavelengths of the quanta define their properties - those with wavelengths (X) between 400 and 700 nm (400 - 700 x 10-9 m) correspond with the visible wavelengths we call light (and within which waveband the quanta are called photons). The waveband of photosynthetically active radiation (PAR) coincides almost exactly with that of light. The white light of the visible spectrum is the aggregate of the flux of photons of differing wavelengths, ranging from the shorter (blue) to the longer (red) parts of the spectrum.
The first studies of the effects of ionizing radiation and radioactive particles dealt with individual organisms and were conducted under controlled laboratory conditions. Effects were generally measured as the LD50 or ED50, doses of radiation that respectively either kills or produces a specific effect in 50 of the subjects tested. When applied outside of the laboratory under natural environmental conditions however, these measures are replaced by the ecological LD50 or ED50, which are generally lower than their corresponding laboratory-based measures of radiation effects. Radiation-induced effects which might not kill an organism outright under As ecological studies and theory began to deal more extensively with higher and more complex levels of biological organization such as populations, communities, and ecosystems, radiation effects studies have also begun to deal with these levels above that of the single organism. Rather than simply exposing individual organisms to a single...
Ionizing radiation using x-ray and gamma-ray beams with even higher energy levels than that of UV irradiation, can also be used in water, wastewater, and sludge disinfection. These ionizing mechanisms displace electrons during beam bombardment (i.e., at which point they are said to ionize), and in the presence of oxygen these displaced electrons elec-trochemically form a type of free radical (called hydroxyl radicals) that is highly toxic to microbial cells. Free radicals are highly reactive, having essentially no activation energy for their reaction. Given the acutely reactive nature of these radicals, they readily attack and destroy hydrogen bonds, double bonds, and ring structures essential to the metabolic utility of various cellular molecules. Yet another operative mechanism, and perhaps the key factor behind disinfection with ionizing irradiation, is that of a polymerizing impact (e.g., DNA thymine dimerization) whereby the biochemical effectiveness of complex molecules is...
The sources of the variation in traits within a population are random mutations in the genetic code, and sorting and recombination of genetic material that occurs during meiosis, a type of cell reproduction. Only a minority of genetic changes may confer an advantage on an individual. In fact, most changes are probably fatal and are not passed on to future generations. Mutations are caused by errors in the biochemical processes of reproduction in which the genetic material is copied for progeny, or by damage from chemical or physical agents such as ionizing radiation.
Electromagnetic radiation includes both radioactivity and low frequency radiation, and both can affect biological processes. Some materials emit small doses of radioactive radon gas. Materials that are good conductors can increasethe low intensity magnetic fields in buildings. Whilst radioactivity is carcinogenic, low frequency radiation is thought by many to be able to cause illness and fatigue.
In the heaviest atoms there is often a large inner tension. They may thereby emit radiation into their surroundings. There are three different forms of radiation alpha, beta and gamma radiation. Gamma radiation is pure electromagnetic radiation. It can penetrate most materials in the same way as X-rays. Alpha and beta radiation are caused by the atom breaking down, reducing the size of the nucleus. Radium (Ra) with the atomic number 88, will decay by radiation through a number of stages and finally become lead (Pb) with the atomic number 82. This process takes thousands of years.
Ial produced by crushing or grinding or resuspended from settled dusts is generally made up of particles with diameters larger than 1 m. On the other hand, particulate material produced by condensation or gas-phase chemical reactions is comprised of many small particles, all much smaller than 1 m in diameter. Figure 5.15.1 illustrates typical particle diameters for a variety of substances, including particulates such as beach sand and pollens. For comparison, this figure also includes the size range for types of electromagnetic radiation, estimates of gas molecule diameters, size ranges for fogs, mists and raindrops, and ranges for inspirable particles.
Dose equivalent (HT) The dose of ionizing radiation absorbed by an organism multiplied by a factor that takes into account the difference in the biological effects of different kinds of radioactive particle having the same energy. It is expressed in sieverts (Sv). 1 sievert is the radiation dose delivered in one hour at a distance of one centimeter from a point source of 1 mg of radium enclosed in platinum 0.5 mm thick. For beta-particles, gamma-rays, and x-rays this factor is 1, but for alpha-particles it is 20. See also dosage.
150 years that this topic has been mentioned in forest literature. Ouis (2003) reviews the range of non-destructive techniques which can be used to detect decay in standing trees. Some employ vibro-acoustical techniques using either vibrations at frequencies within the acoustical bandwidth or sound waves at acoustical or ultrasonic frequencies. The second class of techniques uses methods based on electromagnetic radiation such as radar. Modern destructive testing methods in which only a small sample is extracted from the tree trunk are also of value.
Electromagnetic energy (electromagnetic radiation) Energy propagated by vibrating electric and magnetic fields. It can be thought of as being in the form of waves or as streams of photons (units of light). The energy carried depends on the frequency. The frequency and wavelength are related by the equation where c is the speed of light, X the wavelength, and v the frequency. The electromagnetic spectrum ranges from low-frequency radio waves to high-frequency gamma rays. electromagnetic radiation See electromagnetic energy. electromagnetic sense A sense used by some fish (particularly cartilaginous species) to detect subtle changes in magnetic impulse, which they use to locate prey. Some insects, e.g. fire ants, are also attracted to the electromagnetic fields produced by underground cables, which they subsequently attack. electromagnetic spectrum See electromagnetic energy.
Energy has several forms, some of which are convertible they include chemical energy (energy stored in chemical compounds), electromagnetic energy, potential energy (the capability of doing work), kinetic energy (movement), mechanical energy, radiant energy (light), and thermal energy (heat). Energy is measured in joules.
Metal structures can affect the indoor climate by picking up vagrant electrical currents from electrical installations and distributing them around the building. This can result in changes or increases in the electromagnetic fields in the building, which can affect health by inducing sickness and fatigue. When dumping metals, a certain level of seepage of metal ions to the soil and ground water must be assumed.
Anoxygenic photosynthesis uses energy from sunlight to couple the reduction of C in CO2 to the anaerobic oxidation of S in S0 or H2S. If one is accustomed to thinking of S oxidation in a strictly aerobic sense, then anaerobic S oxidation appears contradictory. Anoxygenic photosynthesis would have been compatible with the anoxic (O2-free) conditions of the earth's primordial atmosphere. It could have been mediated by anaerobic organisms like present-day photosynthetic sulfur bacteria and is believed to have preceded oxygenic photosynthesis (Staley and Orians, 1992). Dominance of anoxygenic photosynthesis would have favored anaerobic respiration or fermentative pathways for obtaining energy from the products of photosynthesis. Consequently one might expect, and certainly one finds, a wide representation of anaerobic microorganisms in soil environments. Many elements can cycle under entirely anaerobic conditions due to the syntrophic relationships among photolithotrophs and anaerobic...
Kinds particulate (e.g. alpha and beta radiation, neutrons, positrons) and electromagnetic (e.g. gamma radiation and x-rays). Alpha particles are made up of two neutrons and two protons and carry a 2+ charge. They do not penetrate tissues well, but produce intense tissue ionization. Beta particles are electrons or positrons, carrying only a single negative charge. They can penetrate several millimeters into tissues, but induce only moderate ionization. Gamma rays and x-rays do not carry a charge, and have no mass, so can penetrate deeper into tissues, creating moderate ion-ization. Gamma rays have higher energy than x-rays. The deleterious effects of ionizing radiation on living tissues is related to the high water content of tissues. The radiation generates highly reactive H and OH radicals that can damage DNA and proteins. See also radical.
Production of metals is polluting and energy intensive. For the people using a building, metals are mainly neutral, even though a large amount of metal is assumed to strengthen the building's internal electromagnetic fields. Metal ions may also be released into the soil around buildings from weather exposed products. This can cause an environmental problem, depending on the amount and type of metal in question lead and copper are the most troublesome. Metal can normally be recycled when it becomes waste, but this may be complicated by additives and coatings.
Light Electromagnetic radiation in the visible spectrum, i.e. with wavelengths ranging from 400 nm (extreme violet) to 770 nm (extreme red). The wavelength of light is the distance from one peak of the electromagnetic wave to the next. The spectrum of light is the span of wavelengths visible to the human eye. White light contains light of all wavelengths. Objects appear colored because they reflect certain wavelengths of light, but not others. While light may be considered as waves of electromagnetic energy, it may also be viewed as discrete packets of energy that carry the electromagnetic field, called photons. A photon has no charge or mass. Its energy depends on the wavelength of the light, shorter wavelengths having higher energy. All photons travel at the speed of light, about 299,492 kps per second. When light is reflected or refracted by certain substances, it is separated into two or more components, such that the wave action of each is concentrated in a different plane. This...
Types of Carcinogens The knowledge that carcinogens act by different mechanisms led to a distinction in two types of carcinogens. The first type are called genotoxic carcinogens, which act either themselves or via metabolites to either damage DNA directly or impair the processes of repair or transcription. This is initiation, as defined above, and the chemicals are called initiators. Examples include nitrosamines, epoxides, and metals such as cadmium, chromium, or nickel. The direct-acting genotoxins are often electro-philic compounds that bind to DNA, similar to the action of mutagens. Others must be biotransformed to be genotoxic and are called precarcinogens. Most genotoxic environmental pollutants are in this category, including chlorinated hydrocarbons, aromatics such as benzene, and PAHs. The mechanism for carcinogenic metals, such as arsenic, chromium, and nickel, is not understood. They are thought to impair DNA replication or transcription by complexing with the DNA or...
Biota may be exposed to ionizing radiation from the environment from both external and internal exposure from radionuclides taken into the organism. For example, terrestrial organisms are exposed externally to radiation from the nearby soil, and aquatic organisms are exposed externally from the radioactivity in the water. Bottom dwellers or benthic organisms are exposed externally by the radioactivity in sediment and both terrestrial and aquatic organisms are exposed internally by radionuclides taken up by the organism. Therefore, in evaluating exposure it is necessary to obtain or estimate the levels of radioactivity in the abiotic and biotic components of the ecosystem. In some cases, there may be measured data available however, often models are necessary to provide an estimate of radioactivity in various compartments.
As previously noted, ionizing radiation is ubiquitous and all living things are, and have always been, exposed to naturally occurring radiation and radioactivity. Moreover, natural background levels of radiation vary widely from place to place levels of radioactivity in soils, sediments, or pathways of exposure may result in elevated intake of natural radionuclides by biota. In this respect, it is important to understand that there may be practical difficulties in establishing protection criteria for radiation which is ubiquitous in the natural environment in comparison to many chemicals that are not naturally occurring. ERAs are expected to continue evolving in light of recent developmental work (such as the ERICA project), the forthcoming update of the UNSCEAR report on effects of ionizing radiation on nonhuman biota, and further developments by ICRP in this area of emerging expertise. Moreover, the IAEA coordination group on the radiological protection of the environment provides a...
Within a building, stairs have practically no side effects. Exceptions that can lead to polluting emissions are impregnated wood stairs, and some paints used both on iron and wooden products. Steel stairs and reinforced brick and concrete stairs can increase the electromagnetic fields in a house.
Exposure is defined only for electromagnetic radiation such as g-rays. The SI unit is based on the number of charges of one sign produced by complete absorption in air. The unit is coulombs per kilogram of air. The older unit of exposure is the roentgen (R) For tissues this conversion is approximate and may vary with type of tissue and g energy. Exposure and dose have frequently been confused with each other, partly because in the units of roentgens and rads they are numerically similar. Exposure refers only to ionization that would occur in air due to electromagnetic radiation such as g- or x-rays. It is the radiation that would be measured by an external dosimeter, such as a film badge clipped to the shirt of a worker. However, it only indirectly indicates how much radiation has been absorbed by the worker. Dose applies to energy absorbed by any material and due to any type of radiation.
The ICRP occupational guideline for radiation protection (1990) limit the dosage received to an average of 20 mSv (2 rem) per year over five years, with a maximum of 100 mSv in any one year. A dosage of 20 mSv with a fatal cancer occupational risk factor of 4 per sievert corresponds to an 8 x 10 4 risk. The NCRP (1993) has defined a negligible individual dose (NID) below which efforts to reduce radiation exposure further are unwarranted. The NID was selected to be 0.01 mSv (1 mrem) per year. This corresponds to 5 x 10-7 added risk of fatal cancer per year.
Ble level for occupational radiation exposure is five rems per year to the whole body. It is believed that this level can be absorbed for a working lifetime without any sign of biological damage. Background radiation is measured in millirems (0.001 rem). The average person is exposed to ionizing radiation from many sources. The environment, and even the human body, contains naturally occurring radioactive materials. Cosmic radiation contributes additional exposure. The use of x-rays and radioisotopes in medicine and den-
Electromagnetic Radiation Electromagnetic radiation is characterized by its wavelength A, or alternatively by its frequency v. The two variables are related by A x v c, with c being the speed of light (c 3 x 108 km s in vacuum). Climatically relevant are mainly the following wavelength ranges (1) ultraviolet radiation, corresponding to wavelengths of less than 400 nm (2) visible light, ranging from 400 nm (blue light) to 750 nm (red light) and (3) infrared radiation, referring to wavelengths longer than 750 nm. Radiation with shorter wavelengths is generally referred to as more energetic. The peak of emission of solar radiation is about 550 nm (green light), while the Earth with its much lower emission temperature has its peak emission at about 11 mm (infrared). The peak of emission is described by Wien's law (Apeak 0.2898 x 10- mK TR). Since these peak wavelengths and the associated distributions are well separated, electromagnetic radiation in climatology is generally classified...
The electromagnetic spectrum (EMS) includes wavelengths of EM radiation ranging from short-wavelength (high-frequency) gamma rays to long-wavelength (low-frequency) radio waves. We focus on the region of the spectrum starting in the ultraviolet and continuing through the microwave wavelengths. Optical sensors are used to measure ultraviolet, visible, and infrared wavelengths, and microwave sensors are used for the microwave portion of the EMS. Radiance at the sensor is a measure of the electromagnetic radiation hitting the sensor's detector Radiance at the sensor is a measure of the electromagnetic radiation hitting the sensor's detector
Radiation measurement for the purpose of protection from exposure requires proper measuring devices and proper measurement techniques. Equipment and units of measure for health protection are designed in terms of absorbed radiation dose. This absorbed dose is defined as the energy imparted to matter by ionizing radiation per unit mass of irradiated material at a given location. This unit of ab sorbed dose is called a rad. The dose equivalent is a quantity used in radiation protection to express all radiation exposure on a common scale. The unit of dose equivalent is the rem. Rads of y and 5 radiation are normally equivalent to rems, and are used interchangeably. The sievert (Sv) is the equivalent SI unit and is equal to 100 rems.
AUnited States National Council on Radiation Protection and Measurements (1991) Effectys of ionizing radiation on aquatic organisms. NCRP Report No. ICQ. international Atomic Energy Agency (1992) Effects of ionizing radiation on plants and animals at levels implied by current radiation protection standards. Technical Reports Series No. 332. Vienna IAEA. dUnited Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) (1996) Effects of Radiation on the Environment. Annex to Sources and Effects of Ionizing Radiation (Report to the General Assembly, with one Annex), Scientific Committee on the Effects of Atomic Radiation. New York United Nations. h Advisory Committee on Radiological Protection (2002) Protection of Non-Human Biota from Ionizing Radiation. Canadian Nuclear Safety Commission (CNSC), INFO-0703, March. Framework for Assessment of Environment Impact (FASSET) (2003) Deliverable 3 Dosimetric models and data for assessing radiation exposures to biota (Prohl G,...
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