PARENT SESSION
3:45 PM to 5:15 PM
Monday, April 22, 2002
Mini-Symposium 6
Biology, Physics, Chemistry
Room: Nevada 8-9-10
, Co-Chair: Siemann, Dietmar¹; LaVerne, Jay²¹University of Florida, Gainesville, FL²Notre Dame, Notre Dame, IN

(MS06-8) Cancer risks associated with prolonged low dose r-irradiation.

Hwang, Sulun^*,1, Lin, Yiping¹, chang, Wushou¹, Hsieh, Wan¹, Guo, How², ¹ Institute of Public Health, National Yang Ming University Medical School, Taipei, Taiwan² Department of Environmental and Occupational Health, Tainan, Taiwan

ABSTRACT-
To assess cancer risk associated with long-term low dose radiation exposure, we conducted a cohort study on the residents and school children who had stayed in the radio-contaminated buildings with Co-60 in the steel rebar in Taiwan. 2,296 male and 2,493 female subjects from 2 to 98 years of age (mean+1 s.d as 29+ 16.15 years old) and received at least 1 mSv per year during 1983 to 2000 were registered. Their exposures were estimated by a Taiwan Cumulative Dosimetry Program (TCD) and were up to 100 mSv per year . These subjects were matched in the National Cancer Registry Program of Taiwan from 1983 to 2000, while 107 cancer cases were identified and confirmed with pathological diagnosis. The cancer risk was determined by the standardized incidence rate (SIR) adjusted for age and sex, as compared with the reference population in Taiwan. Statistically significant increases in the risks of uterine cancers (SIR=8.33, p<0.05), thyroid cancers (SIR=4.52, p<0.05), lymphoma (SIR=4.14, p=<0.05), breast cancers (SIR=2.89, p<0.05), and cervix cancers (SIR=2.37, p<0.05) were observed and with at least 5 cases of each. No significant increase in the risks of leukemia was observed (SIR=2.06, p=0.2). By employing the minimum latency periods of two years for lymphoma and leukemia and five years for solid cancers to obtain more conservative risk estimates, statistically significant increases in the risks of uterine cancers (SIR=8.33, p<0.05), thyroid cancers (SIR=3.95, p<0.05), lymphoma (SIR=4.14, p<0.05), breast cancers (SIR=2.7, p<0.05), and cervix cancers (SIR=2.11, p<0.05) were again observed, also with no significant increase in the risks for leukemia (SIR=1.65, p=0.45). In this preliminary observation, several cancers are surprisingly observed significantly increased in the exposed population with prolonged low dose-rate environmental irradiation. Further follow-up will be warranted in the future (supported by the National Science Council, Taiwan and NHRI, Taiwan).

KEYWORDS: radiation, cancer, low dose, epidemiology