Lifetime exposure to more than 100 millisieverts of radiation presents a significant risk of cancer, according to a preliminary finding of the Food Safety Commission reached at a meeting July 21.
Lifetime exposure to more than 100 millisieverts of radiation presents a significant risk of cancer, according to a preliminary finding of the Food Safety Commission reached at a meeting July 21.
The calculation includes radiation from food and external exposure.
The committee, established under the Cabinet Office, has been tasked by the Ministry of Health, Labor and Welfare to assess the effects of exposure on human health over a lifetime.
The committee will make its final decision as early as next week and will present it to the ministry.
On March 17, the ministry set provisional benchmarks, backed by the Food Sanitation Law, to restrict distribution of food contaminated by the Fukushima No. 1 nuclear power plant crisis.
Some studies contend that children and fetuses are more vulnerable to radiation than adults. The panel issued a statement saying the 100-millisieverts level may not apply to all people of different ages.
According to the International Commission on Radiological Protection (ICRP), exposure to 100 millisieverts raises the risk of developing cancer by 0.5 percent.
However, some ministry officials are skeptical that an exact exposure reference point would be of value because most people would find it difficult to take precautions over such a broad time frame.
The Food Safety Commission initially attempted to perform the assessment only for exposure through ingestion. But the committee found that very few relevant studies conducted overseas, including the paper on which the ICRP based its recommendation, discussed exposure through ingestion and external exposure separately.
This led the committee to incorporate both types of exposure to create a lifetime exposure standard.
Natural radiation exposure, which is about 1.5 millisieverts annually in Japan, is not included in the calculation.