isa 7 Effects of ionizing radiation in children Wataru W. Sutow, M.D.,* and Robert A. Conard, M.D.** HOUSTON, TEXAS, AND UPTON, N. Y, gested that young children might be more susceptible than adults to the carcinogenic action of radiation. Other data, however, show that leukemogenesis also may be associated with diagnostic radiation in the adult’® and that the incidences of radiation-induced REVIEW of recent literature was undertaken to obtain a perspective of radiation effects on humanbeings, particularly the effects on children. Although numerous re- ports indicate the occurrence of specific deleterious effects after high doses of radiation, documentation of damage in man following chronic exposure to low doses and low dose rates is meager. The question of differential sensitivity in lung tumors among asbestos and coal gas workers, of bladder tumors in chemical workers, and of leukemia among radiationtreated males with spondylitis in England increased with increasing age.*! Lack of knowledge regarding the basic mechanisms in radiation carcinogenesis (and spontaneous relation to age is particularly relevant to pediatric considerations. The publications suggesting that fetal irradiation at diagnostic roentgenographic dose levels may be asso- cancer), in addition to the difficulties in- ciated subsequently with increased leukemogenesis and carcinogenesis" * * have emphasized the need to obtain more data on human beings. The occurrence of thyroid cancer after irradiation of the thymus during in- herent in the interpretation of epidemiologic data, warns against uncritical acceptance of conclusions seemingly shown.11"14 Considerable data have accumulated describing the effects of radiation on adult human beings. However, less is known about the age dependence of such effects, particularly in regard to children. It is believed that the young are somewhat moresensitive to radiation than are adults and this is generally found to be true in studies on animals and from limited experience with irradiated human beings. In this paper, the somatic and genetic effects of radiation in the human being will be reviewed with special attention to what is known about the relative sensitivity of children. Also, the fancy* * % 7 and the age pattern of leukemia in the Japanese A-bomb data* ® have sugFrom The University of Texas M. D. Anderson Hospital and Tumor Institute, Pediatric Section, Department of Medicine, Houston, Texas, and the Medical Division, Brookhaven National Laboratory, Upton, Long Island, N. ¥. This work was supported in part by Public Health Service Research Career Award No, CA-2501-2 and by the U.S. Atomte Energy Commission. *Address, The University of Texas M. D. Anderson Hospital and Tumor Institute, 6723 Bertner Drive, Heuston, Texas. **Address, Medical Division, Brookhaven National Laboratory, Upton, Leng Island, N. Y¥ current attitudes toward the hazards of low- level radiation in children will be examined. ai n £ fae i Ph) es 4 658 2 OAT ene meet mae i IB aETTSTn ater THIS