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PEDIATRICS is the official journal of the American Academy ofPediatrics. A monthly publication, it has been published continuously since 1948. PEDIATRICS is owned, published, and trademarked by the American Academy of Pediatrics, 141 Northwest Point Boulevard, Elk Grove Village, Illinois, 60007. Copyright © 1998 by the American Academy of Pediatrics. All rights reserved. Print ISSN: 0031-4005. Online ISSN: 1098-4275.
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AMERICAN ACADEMY OF PEDIATRICS
Committee on Environmental Health
Risk of Ionizing Radiation Exposure to Children: A Subject Review
ABSTRACT. Exposure of children to ionizing radiation most commonly is from the environment, chiefly through cosmic rays and radon, or from medical technology. Medical radiation exposure occurs during diagnosis, therapy, and dental radiography.More is known about the biological effects of exposure to ionizing radiation than to nonionizing radiation from microwaves, radiowaves, and the electrical fields of other electrical appliances. This review applies only to sources of ionizing radiation and does not include the potential risks of indoor radon. The effects on children of ionizing radiation have been studied from war activities andenvironmental accidents. Projections are made from that data to help pediatricians evaluate risk from radiation when ordering radiographs.
mia to be higher than that associated with childhood exposure.7
pidemiologic studies have shown that persons exposed to high levels of ionizing radiation have an increased risk of cancer, particularly leukemia, and later in life, breast andthyroid cancer.1 In addition, some epidemiologic studies have found that radiation exposure during childhood carries a higher risk of cancer than exposure at other ages.2,3 However, it should be noted that these reports studied exposures at relatively high doses (such as those seen at Hiroshima and Nagasaki in Japan). Therefore, the risks of developing cancer from childhood exposure to low levelsof radiation from diagnostic x-ray examinations are not well-quantified but are probably very small.4 The Figure shows the measurements used in determining radiation exposure.
Epidemiologic studies indicate that the risk of breast cancer is increased in women who were exposed to high levels of radiation during childhood. Breast cancer rates were higher among female atomic bombsurvivors who were 10 to 19 years of age when exposed to the bomb than among those who were older at that time.8,9 The excess relative risks found in this study were 2.42 per Sievert for women exposed between 10 and 19 years of age, 1.25 per Sievert (100 rem) for women aged 20 to 39 years at exposure, and 0.48 per Sievert for women aged 40 years and older at the time of the bomb. A higher occurrenceof breast cancer was also observed among women who were younger than 10 years at the time of the bomb—a surprising finding because it is an age at which they would have had very little breast tissue. The latent period for radiogenic breast cancer is a minimum of about 10 years. Radiation-related breast cancers have age distributions and histopathologic characteristics similar to those of breastcancer from other causes, known or unknown.5,8 Breasts should be shielded when possible when obtaining necessary diagnostic or therapeutic radiation.
Studies of atomic bomb survivors showed the risk of mortality from leukemia to be elevated at doses above 0.4 Gray (40 rad), with the excess relative risk ranging from 4.2 to 5.2 per Sievert (100 rem). The risk of leukemia was also...