Introduction of a method to calculate cumulative age- and gender-specific lifetime attributable risk (LAR) of cancer in populations after a large-scale nuclear power plant accident.

Christopher Rääf,Mats Isaksson,Nikola Markovic,Martin Tondel,Robert Wålinder,Jed N Lampe

doi:10.1371/journal.pone.0228549

Abstract

The effect of age and gender in risk estimates related to long-term residence in areas contaminated by nuclear power plant fallout was evaluated by applying the lifetime attributable risk (LAR) concept to an existing exposure model that was previously used for cumulative effective dose estimates. In this study, we investigated the influence of age distribution on the number of cancer cases by applying five different age distributions from nuclear power–producing countries (India, Japan, South Korea, and the United States), and Egypt because of intentions to develop nuclear power. The model was also used to estimate the effective dose and gender-specific LAR as a function of time after fallout for the offspring of the population living in 137Cs fallout areas. The principal findings of this study are that the LAR of cancer incidence (excluding non-fatal skin cancers) over 70 y is about 4.5 times higher for newborn females (5.4% per MBq m-2 of initial 137Cs ground deposition) than the corresponding values for 30 y old women (1.2% per MBq m-2 137Cs deposition). The cumulative LAR for newborn males is more than 3 times higher (3.2% versus 1.0% per MBq m-2 137Cs deposition). The model predicts a generally higher LAR for women until 50 y of age, after which the gender difference converges. Furthermore, the detriment for newborns in the fallout areas initially decreases rapidly (about threefold during the first decade) and then decreases gradually with an approximate half-time of 10–12 y after the first decade. The age distribution of the exposed cohort has a decisive impact on the average risk estimates, and in our model, these are up to about 65% higher in countries with high birth rates compared to low birth rates. This trend implies larger average lifetime attributable risks in countries with a highly proportional younger population. In conclusion, the large dispersion (up to a factor of 4 between newborns and 30 y olds) in the lifetime detriment per unit ground deposition of 137Cs over gender and age in connection with accidental nuclear releases justifies the effort in developing risk models that account for the higher radiation sensitivity in younger populations.

Highlights

Conventional radiological risk assessments for stochastic radiation effects resulting from nuclear reactor accidents or other accidental releases of radionuclides entail the use of the effective dose from various exposure pathways (e.g., [1,2,3,4])
The CUMLARWB values differ greatly between newborns and 30 y olds, and the model predicts a time-integrated lifetime attributable risk that is more than 4.5 times higher for newborn girls than for 30 y old females, for those residing in the affected area more than 70 y
Compared to the commonly used risk-assessment model proposed by ICRP using average effective dose, the use of lifetime attributable risk, as elaborated by BEIR [7] and Environmental Protection Agency (EPA) [8], can enable radiological risk estimates from different nuclear power plant release scenarios that are more sensitive to the age and gender of individuals

Summary

Introduction

Conventional radiological risk assessments for stochastic radiation effects (predominantly radiation-induced cancer) resulting from nuclear reactor accidents or other accidental releases of radionuclides entail the use of the effective dose from various exposure pathways (e.g., [1,2,3,4]). The effective dose is suitable for comparing the risk that one or more representative fictive individuals develop cancer in various scenarios. It can be considered for use in an optimization tool in planned exposure situations as well as an input for managing mitigation measures in existing exposure situations and in radiological and nuclear emergencies. According to the ICRP [6], a coefficient of about 0.05 per Sv (representing roughly a 5% absolute risk of attaining a radiation-induced cancer per unit effective dose in the case of uniform whole-body irradiation) is used as an average for exposed members of the public, regardless of sex distribution

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