Maximum permissible dose

Maximum Permissible Dose Equivalent (MPD)—The greatest dose equivalent that a person or specified part thereof shall be allowed to receive in a given period of time. 

Statements on Maximum Permissible Dose from Television Receivers and Maximum Permissible Dose to the Skin of the Whole Body, Am. J. Roentgenol., Radium Ther. and Nucl. Med. 84, 152 (1960) and Radiology 75, 122 (1960)... 

Statements on Maximum Permissible Dose from Television... 

At the Second International Congress of Radiology held in Stockholm in 1928, the International X-ray and Radium Protection Commission was established. At the fifth Congress held in London in 1950, the name of the Commission was changed to the International Commission on Radiological Protection, ICRP, and the term tolerance dose was changed to maximum permissible dose . The maximum permissible dose for radiation workers was determined as 0.3 R/week ( 3 mSv/week) or 0.2 R/day,... 

International Commission on Radiological Protection 0.3 R/week Maximum permissible dose (MPD)... 

The way in which the maximum permissible dose was understood to be at the time was that it should be the quantity of ionising radiation which is determined to not cause any somatic effects which might be detected at any moment of a person s lifetime, based on the present understandings on radiation . However, starting with the recommendation made in 1958, the hereditary effects began to be included. 

Since then, in 1%5, there was a new recommendation published, stating that the purpose of radiation protection is to prevent the early effects of radiation, as well as to limit the late effects to within an acceptable level . Based on these basic principles, the maximum permissible dose was limited to 5 rem/year (5 mSv/year) for the general public. 

Radiation is a major hazard and its stochastic effects should not be underestimated (Ballance et al., 1984). For instance, -particles emitted by have a maximum range of 6 m in air, but less in glass (0.38 cm). Perspex (Plexiglas, 0.64 cm) or water (0.84 cm). The maximum permissible occupational skin dose equivalent in the United States is 30000 mRem/year (7500 mRem/3 months) but six times lower for the lens of the eye. The dose equivalent rate at the surface of a glass container with P (such as Combi-v-vial ) can be close to 500 mRem/hmCi whereas it may be over 170000 mRem/hmCi outside a plastic syringe with a P solution (Zoon, 1987). Without precautions, the maximum permissible dose can thus be received in a matter of minutes or even seconds. In contrast, S does not penetrate the walls of typical containers or the dead layer of skin cells. The main hazard of S is due to inhalation. 

Although regulations allow an annual maximum permissible dose to radiation workers, one should make considerable efforts to adopt strict protective measures in working with radiations so as to reduce the radiation dose as low as reasonably achievable (ALARA). Under this concept, techniques, equipment, and procedures are critically evaluated and adopted to minimize the radiation dose to the worker. The NRC has set two goals for a radiation worker to achieve 10% of the occupational dose per quarter (Action level I) and 30% of the occupational dose per quarter (Action level II). If these limits are exceeded, corrective action must be taken or higher limits must be justified for a particular situation. The principles of radiation protection described later should be followed strictly to achieve ALARA compliance. 

Atrazine was not the only chemical to be banned - the sale and use of alachlor on soya was also prohibited. In addition, maximum permissible doses of several chemicals were reduced significantly (seeZanin etal., 1991). 

The International Commission on Radiological Protection (ICRP) recommends specific limits of dose, applicable to stated time intervals (a quarter, a year, and so forth) as guidance for protection of radiation workers these are called maximum permissible doses and are applicable to individuals exposed continuously or intermittently from time to time as their work requires (40). To assist the planning of nuclear designs and operations so as to minimize, appropriately, the low level exposure of members of the public which may ordinarily result from normal operations, dose limits for individual members of the public are recommended by ICRP which are one-tenth or less of the maximum permissible doses for radiation workers. Though these maximum permissible doses and dose limits have little to do directly with the control of major radiation emergencies (i.e., reactor accidents) they are quoted in brief in Table VII. 

According to current regulations, the maximum permissible dose of strontium-90 in the body of an adult is 1 fiG (lx 10 Ci). Using the relationship rate = kN, calculate the number of atoms of strontium-90 to which this dose corresponds. To what mass of strontium-90 does this correspond The half-life for strontium-90 is 28.8 yr. 

ICRP Publication 1 was adopted in 1958 and was available in the following year. This document gave background for a comprehensive protection system based on the knowledge that "Exposure to ionizing radiation can result in injuries that manifest themselves in an exposed individual and in his descendants these are called somatic and genetic injuries respectively". Essentially the recommended system comprised a dose limitation concept based on "maximum permissible doses" applied to different exposure categories. Probably the best known of diese recommendations is the formula D = 5(N-18), where D is the maximum allowable accumulated dose in rem units and N the age in years. 

The second was for medical uses such as crude drugs. Recently in the fad for health foods, many people ingested many kinds of foods containing germanium. Several people were poisoned to death since they had ingested these health foods for a long time, and had taken many times a maximum permissible dose. Thus, some companies were prosecuted for a violation of the Drugs, Cosmetics and... 

Most estimates of the thyroidal radiation dose consequent to exposure are based upon metabolic parameters determined for other radioiodines. For example, Colard et al. (1965) calculated thyroidal burdens from chronic (1 iiCi h ) absorption for a number of radioiodines, assuming a stable iodine intake of 100 //g d . In the case of I, such an exposure was estimated to lead to the deposition of 5700 /specific activity, however, one /iCi of represents 5.9 mg of iodine. Hence, the data of Colard et al. (1965) would require the deposition of 34 g of iodine (all as I) in the thyroid. This quantity corresponds to several thousand times the average value of 0.012 g iodine in the thyroid (ICRP, 1975). The intake per day for the maximum permissible dose is discussed in Section 4.7. 

The Atomic Energy Commission adopted the recommendations of the NCRP in formulating regulations for radiation protection in the civilian atomic-energy program. The AEC had used the NCRP s occupational maximum permissible doses in its own installations and operations since its establishment in 1947. 

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