Internal Exposure - Responses Immediately after a Nuclear Hazard -

As causes of internal exposure, both inhalation and ingestion of foods need to be taken into consideration. For example, when calculating exposure doses for children engaging in outdoor activities at places with high ambient doses, doses due to internal exposure account for only around 2% to 3% and exposure doses are mostly due to radiation from outside of the body. Therefore, people do not have to be too nervous about exposure through inhalation and proper daily hygienic control (taking a bath, getting a haircut, washing hands, cleaning, and doing the laundry, etc.) is effective in reducing internal exposure to some extent.

In the meantime, regarding the possibility of internal exposure caused by ingestion of foods, attention needs to be paid to wild foods or other foods whose safety cannot be confirmed. In particular, special attention is required for ferns and mushrooms, which have a property to concentrate cesium.

Unlike ambient dose rates, internal exposure doses cannot be easily checked personally, so it is recommendable to refer to measurement results, etc. released by relevant ministries and agencies. Data on radioactivity concentrations in foods is released by the Ministry of Health, Labour and Welfare and the Ministry of Agriculture, Forestry and Fisheries.

• Included in this reference material on March 31, 2013
• Updated on March 31, 2015