In Utero Exposure To Ionising Radiation And Cancer Risk In The Southern Urals, Russian Federation

Isabelle DELTOUR, IARC, France
KRESTININA L. 2 , TSAREVA Y. 3 , TOLSTYKH E. 2 , VOSTROTIN V. 3 , SCHONFELD S. 1 , SOKOLNIKOV M. 3 , AKLEYEV A. 2 , SCHÜZ J. 1

1 Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France
2 Urals Research Center for Radiation Medicine, Chelyabinsk, Russian Federation
3 Southern Urals Biophysics Institute, Ozyorsk, Russian Federation

Background: Limited evidence is available on whether in utero exposure to low-dose ionizing radiation increases the risk of cancer over the lifetime.
We report on the analyses of two in utero exposed population cohorts from the Southern Urals (Russian Federation).

Methods: The respective cohorts comprised 8466 offspring of female workers of a large nuclear facility (the Mayak Production Association) and 11,470 offspring of women living in areas along the Techa River contaminated by nuclear accidents and nuclear waste from the same facility, with detailed dosimetry. Excess relative risk (ERR) and relative risks (RR) models were used to estimate the hematological and solid cancer risks over the lifetime associated with in utero exposure, adjusted for post-natal exposure, age, sex and ethnicity.

Results: The combined cohort totaled 700,504 person-years at risk over the period of hematological malignancies incidence follow-up, yielding 58 incident cases. The adjusted risk of hematological malignancies was increased in subjects who received elevated in utero doses (ERR: 1.27; 95% confidence interval [CI]: -0.20 to 4.71, for doses above 80 mGy), and the risk increased consistently per 100 mGy of continuous exposure in utero (ERR: 0.77; 95% CI: 0.02 to 2.56).
During the 554,411 person-years at risk in the solid cancer analyses, 369 cases were observed, showing a RR of 0.72 (95% CI = 0.39 to 1.22) for in utero doses above 80 mGy.

Conclusions: The results suggest a positive association between in utero exposure to ionizing radiation and risk of hematological malignancies up to age 60, but the small number of outcomes precludes firm conclusions. There was no evidence of an association between solid cancer risk and in utero radiation exposure in the current data. Continuation of cancer follow-up in this unique combined cohort is important given the relatively young age of cohort members with respect to cancer.