Effects of preconceptional irradiation on mortality and cancer incidence in the offspring of patients given injections of Thorotrast.
BACKGROUND
Findings from a British case-control study suggest that a preconceptional paternal external radiation dose of more than 100 mSv (10 rem) is significantly related to risk for leukemia and non-Hodgkin's lymphoma in offspring. The suggestion, however, has not been supported by experimental or other epidemiologic studies.


OBJECTIVE
The purpose of this study was to investigate if preconceptional irradiation of males and females from internally deposited radionuclides affects mortality and risk of developing cancer in their offspring.


METHODS
The offspring of 260 females (n = 143) and 320 males (n = 226) who lived longer than 1 year after receiving Thorotrast (a compound no longer in use) for cerebral arteriography were studied for mortality rate and the risk for developing cancer. Thorotrast was used as a contrast medium containing a 20% colloidal solution of thorium dioxide-Th 232, an alpha particle-emitting radionuclide, which is retained lifelong in nearly all organs. The offspring of the exposed patients were identified by manual linkage with the municipal population registers and followed-up for vital status by computerized linkage with the Danish National Central Population Registry and for incidence of cancer by computerized linkage with the Danish National Cancer Registry. The standardized mortality/morbidity ratios (SMRs) for death and for site-specific incidence of cancer in the offspring were calculated as ratios of the observed rates in the study population to the expected rates in the general population.


RESULTS
After a median follow-up of 40 years, four cases of cancer (breast [one], uterine cervix [one], melanoma of skin [one], and retinoblastoma [one]) versus 2.9 cases expected, developed among 143 children born to mothers who received injections of Thorotrast (SMR = 1.4; 95% confidence interval [CI] = 0.4-3.5), while six cases of cancer (one case each of cancer of lung, testis, thyroid, and Hodgkin's lymphoma and two cases of melanoma of skin), versus 4.5 expected, occurred among 226 children of exposed fathers (SMR = 1.3; 95% CI = 0.5-2.9). No case of leukemia or non-Hodgkin's lymphoma occurred in any of the offspring studied. Mortality was lower than expected both for children of exposed mothers (SMR = 0.7; 95% CI = 0.3-1.5) and of exposed fathers (SMR = 0.5; 95% CI = 0.2-1.0).


CONCLUSIONS
This study does not support the previously proposed association between parental exposure to radiation and the risk of childhood leukemia and lymphoma. Furthermore, since mortality from all causes was not increased in any offspring, our results do not support the belief that preconceptional parental low-dose exposure to alpha radiation increases the incidence of cancer or mortality in the offspring.
Andersson
M
M
Danish Cancer Society, Division for Cancer Epidemiology, University Hospital, Copenhagen.
Juel
K
K
Ishikawa
Y
Y
Storm
H H
HH
D000293:Adolescent; D000328:Adult; D000512:Alpha Particles / Q000009:adverse effects*; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D018811:Maternal Exposure / Q000009:adverse effects*; D009026:Mortality; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology*; D018812:Paternal Exposure / Q000009:adverse effects*; D013911:Thorium Dioxide / Q000009:adverse effects*; D013997:Time Factors
D013911:Thorium Dioxide