Environmental Medicine Integrating a Missing Element into Medical Education (1995) / Chapter Skim
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Case Study 37: Ionizing Radiation
Case Study 37: Ionizing Radiation
Pages 639-673
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From page 639... ...
See page 35 for more information about continuing medical education credits and continuing education units. Guest Technical Editor: Niel Wald, MD Peer Reviewers: John Ambre, MD, PhD; Charles Becker, MD; Jonathan Borak, MD; Joseph Cannella, MD; Alan Ducatman, MD; Alan Hall, MD; Richard J
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From page 640... ...
A member of the highway patrol, who was first on scene and noticed the radioactivity placard on the truck, contacted a health physicist from the regional office of the Department of Energy. The health physicist found that the driver of the truck and his assistant are externally contaminated with the radioactive material, which is emitting beta and gamma radiation.
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From page 641... ...
The purpose of this document is to help clinicians answer patients' questions about the early and long-term effects of radiation exposure, the risks of radiation in diagnostic and therapeutic medical procedures, and the potential dangers of radiation to the fetus and future generations. Events just before the turn of the century, which included Roentgen's discovery of X rays and Becquerel's recognition of natural radioactivity, allowed us to understand how radiation is produced and how it interacts with matter.
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From page 642... ...
, followed in order by beta particles and electrons. X radiation and gamma radiation interact with matter by transferring energy to electrons.
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From page 643... ...
Biologic effectiveness rem DOSe of any form of ionizing radiation that produces the same biological effect as 1 roentgen; 1 rem -1 red x Radiation Weighting Factor (RWF) , where the value of RWF depends on the type of radiation as follows: X radiation = 1.0 gamma radiation = 1.0 beta =1 .0 alpha = 20 neutrons = 5 to 20, depending on their energy A new System Internationals (Sl)
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From page 644... ...
If the radioactive material in the case study had been an alpha-emitterinstead of a beta and gamma emitter, would the biologic effects be greater? Explain.
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From page 645... ...
or in areas in Czechoslovakia, have increased internal radiation exposure due to inhalation of radon, as well as increased external radiation exposure due to uranium in the soil.
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From page 646... ...
The current deposits of radioactive waste generated by production and use of atomic weapons and nuclear power reactors will remain a potential exposure hazard for ~ o,ooo years or more. Radiation exposure incurred for medical reasons can contribute the greatest dose from artificial sources.
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From page 647... ...
In contrast to environmental exposures, medical procedures usually restrict radiation to local areas. However, during the course of exposing only a small fraction of the body, relatively large doses may be delivered to the bone marrow, which, in comparison to other parts of the body, is very sensitive to radiation.
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From page 648... ...
. Radiation exposure of the U.S.
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From page 649... ...
, making incremental incidences due to radiation exposure difficult to detect; (3) radiation-induced cancer cannot be distinguished from cancer due to other causes (although investigators using new molecular biology techniques are attempting to make this distinction possible)
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From page 650... ...
Accidental releases of radioactive materials may also occur during transport of radionuclides or at sites storing them. Currently, low-level radioactive waste can be accepted at two commercial storage sites: Barnwell, South Carolina, and Hanford, Washington.
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From page 651... ...
Can, Additiona/ information for the case study: The radioactive material has been identified as an aqueous solution of potassium iodide, which was prepared from iodide-131. The cargo was being delivered to a repository for storage of low-level radioactive waste.
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From page 652... ...
The latent period between radiation exposure and clinical recognition of leukemia ranged from 2 to is years. Rapidly dividing cells are the most sensitive to ionizing radiation.
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From page 653... ...
The latency period for solid tumors due to radiation exposure is generally one or more decades. Interestingly, an increase in pancreatic cancer, the fourth leading type of fatal cancer in the United States, was not observed in atomic bomb survivors and has been observed inconsistently in other irradiated human populations (i.e., no clear relationship to dose or time after exposure could be identified)
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From page 654... ...
Genetic Effects In nonhuman forms of life, the developmental and genetic effects of O Genetic effects due to ionizing ionizing radiation are well documented. Radiation exposure in these radiation are well documented life forms results in congenital abnormalities and mutations that are in animals and other non transmitted to immediate and remote offspring.
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From page 655... ...
He says he did not come in contact with the radioactive material (5) Is the boy a hazard to those with whom he has come in contact since the accident?
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From page 656... ...
Depending on the exposure dose, these subsyndromes (i.e., hematopoietic, gastrointestinal, and neurovascular) , which make up the acute radiation syndrome, may be discrete or overlapping (Table 6)
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From page 657... ...
Acute radiation doses exceeding 600 rem to the abdomen or whole body usually result in significant damage and reproductive impairment of rapidly proliferating crypt stem cells, thus producing the gastrointestinal tract subsyndrome. The existing mucosa is shed, preventing normal absorption and causing the gut to leak electrolytes and blood.
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From page 658... ...
If the immediate signs and symptoms after a local radiation exposure include erythema of skin and severe pain, the local absorbed dose is probably in excess of 1000 reds. Evidence of transepithelial injury and dry desquamation may follow.
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From page 659... ...
A useful and sensitive biomarker for dose estimation in acute whole-body radiation exposures, as well as to predict the long-term health risks in large populations exposed to low levels of radiation, is the chromosome aberration assay. Radiation induces several nonspecific but characteristic chromosomal abnormalities, particularly bicentric chromosomes.
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From page 660... ...
Details of sample preparation and the names of laboratories able to perform cytogenetic assays for radiation exposure can be obtained from REAC/TS (telephone: [615]
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From page 661... ...
O The psychologic effects of actual or potential radiation exposure are often overlooked. Early Considerations Decontamination If radioactive materials are present in a workplace, it is important to have decontamination materials available and a written plan for their utilization.
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From page 662... ...
Local Radiation Injury Radiation exposures that produce only erythema (300-1 coo red) can be treated as first-degree burns.
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From page 663... ...
i Continue Random | | Sibling/Parent l I Platelets I I Single patched Donor | E rnergency Observation Surgery Folbw-up Surgery | Burn Care | I - Thermal | I - Radiation I l r , | Folbw-up l fiery | * Whole-body exposures greater than 4 Gy may require bone marrow transplantation or administration of colony-stimulating factors or other hematopoietic growth factors that stimulate proliferation of hematopoietic stem cells.
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From page 664... ...
The town switched to an alternate source of drinking water. Two weeks later, the state public health department declared the river water safe, and the town resumed using the river as its source of drinking water.
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From 1gSO to 1g60, attention centered on genetic effects of radiation exposure, and recommendations were proposed to limit exposure to the equivalent of s rem/year, which applied to both the general public and workers. Because any amount of radiation exposure poses some risk, all standards now employ a philosophy that radiation exposures should be limited to levels that are as low as reasonably achievable (ALARA)
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From page 666... ...
annual equivalent dose limit to skin, hands, and feet ICRP, 1991 0.1 rem (1 mSv) annual effective dose limit, and, if needed, higher values provided that the annual average over 5 years does not exceed 0.1 rem 1.5 rem (15 mSv)
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From page 667... ...
Parental radiation exposure and childrents health: are there effects on the second generation? In: Wilkinson GS, ed.
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From page 668... ...
Wald N Acute radiation injuries and their medical management.
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From page 669... ...
Albuquerque Operations Office (505) 844-4667 PO Box 5400 Albuquerque, NM 87115 Region 5 (Illinois, Indiana, lows, Michigan, Minnesota, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin)
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From page 670... ...
For example, it is not known whether the boy contacted the material and subsequently ingested radioactive material through hand-to-mouth activity, which would result in an internal contamination hazard. An external radiation hazard could exist if the boy contacted the material and is carrying radionuclides on his skin.
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From page 671... ...
lodide-131 is not an alpha-emitter; however, if the radioactive material was emitting alpha particles and the material was ingested, the biologic effectiveness would be greater. The RWF for alpha particles is 20, which indicates a given dose of alpha radiation is twenty times more biologically effective than the same dose of beta or gamma radiation.
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From page 672... ...
If the boy did not contact the radioactive material, he presumably received less radiation than the driver and his assistant, and therefore, would be at much less risk. A small proportion of persons exposed to radiation will develop cancer as a result; if exposed persons do develop cancer, it may never be certain whether the cancer was the result of radiation exposure or other causes.
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From page 673... ...
. No immediate clinical symptoms have been associated with the amount of radiation these patients were likely to have received by ingesting orcontacting the contaminated water, and the additional long-term risk of cancer at these radiation levels is negligible.
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