Japan’s Nuclear Regulatory Authority has released guidelines following new research into the effects of exposure to nuclear radiation in humans.
The authority recommends that those living within a 30-km radius of a nuclear crisis of the magnitude of that at the Fukushima Daiichi nuclear power plant should be given iodine as quickly as possible. The authority’s research suggests that this should reduce by about 20% radiation that comes into contact with the thyroid gland while breathing, Fuji TV reported.
The guidelines also recommend that those living within 5 km of a disaster site be evacuated outside of the 30-km exclusion zone, where exposure to radioactive material is around 100 times lower. The authority added that the 30-km exclusion zone could be expanded in the case of adverse weather conditions.
Although the guidelines are the result of the authority’s latest research, the Nuclear Safety Commission recommended local authorities instruct evacuees leaving the exclusion zone to ingest stable iodine to protect against thyroid cancer back on March 16, 2011, according to the International Atomic Energy Agency (IAEA).
The recommendation was also made by the World Health Organization decades earlier. In a 1999 guideline, the WHO recommended the stockpiling of stable iodine. However, it added, “For adults over 40, the scientific evidence suggests that stable iodine prophylaxis not be recommended unless doses to the thyroid from inhalation are expected to exceed levels that would threaten thyroid function. This is because the risk of radiation induced thyroid carcinoma in this group is very low while, on the other hand, the risk of side effects increases with age.”