2013 Volume 9 Issue 3 Pages 206-220
Objective. The accidents at the Fukushima nuclear power plants following the Great East Japan Earthquake in 2011 resulted in a huge amount of emissions of radioactive substances. The public may have special concerns regarding these plants and radiation-related health risks. Advanced method of life cycle impact assessment evaluates potential human health impacts throughout of product life cycle. This study aimed at the development of method which reflect geographical conditions of Japan and climate conditions of 2011 March and applied this to evaluate increment of health impacts caused by the severe accident of nuclear power plants. Based on the preliminary result of evaluation using the existing characterization factor, we concentrated on the assessment of health impact of cancer caused by the I131 emission to the air.
Methods. LCIA methods generally provide site generic characterization factors (including country-specific factors) to give a priority to the application to LCA. We developed a method which includes fate, exposure, effect and damage analysis in order to improve the quality of assessment. The developed method considers the location (emission site), temporal conditions (2012/March/11th to 29th), population (density and age distribution) and weather conditions (precipitation, wind). The calculated result can be expressed as the increment of the risk of cancer and that of the damage on human, namely, loss of life expectancy.
Results. The incremental risk of cancer and the loss of life expectancy caused by the emission of I131 from Fukushima nuclear power plant were estimated. Both of them were evaluated for each grid cell (3km×3km). The incremental risk exceeded 10-4 in eastern Fukushima and Ibaraki prefecture and exceeded 10-5 in Kanto region including metropolitan area. The estimated human health damage varies with the slope of dose-response relationship, the maximum value is estimated around 30,000 years. The contribution of external exposures is comparatively higher than those of internal exposure such as inhalation and ingestion, because we took into account the indoor exposure of gamma radiation. Average health impact per capita in Fukushima prefecture was 2 days in the maximum. Potential damage on human health in Tokyo is also estimated high (more than 5,000 years) because of the higher population density as well as Fukushima and Ibaraki.
Conclusions. Estimated health impacts of I131 have a wide range varied from 5,000 to 30,000 years. Nevertheless, our model reflecting environmental, geographical and temporal conditions contributed to improve the quality of assessment and the result would be expected as the first study estimating potential of human health damage. The maximum value was the same digit number with the annual health impact (normalization value) of indoor air pollution (84,000 years) and noise (69,000 years) in Japan and it was less than these of urban air pollution and climate change. This study concentrated the damage caused by the emission of I131, the impact of Cs137 was out of scope, because of the difficulty of exposure in a long period of time. The inclusion of Cs137 in the assessment would be a next issue of this study.
