EDITORIAL: Government needs to set clear overall radiation safety standards

The Food Safety Commission of the Cabinet Office has proposed a safety standard for lifetime exposure to radiation. A lifetime dose of 100 millisieverts or more is likely to result in adverse health effects like increased cancer risk, according to the panel's proposed protection standard concerning exposure to radiation released from the Fukushima No. 1 nuclear power plant.

The standard represents an upper limit on a lifetime dose covering internal exposure, mainly from radioactive materials taken into the body through eating contaminated foods, and external exposure from outside sources of radiation.

The figure includes neither the average background radiation of 1.5 millisierverts a year Japanese receive from natural sources nor the 2.3 millisieverts from medical equipment like X-ray machines.

The term "lifetime exposure" has a heavy connotation. Many people are probably wondering how it is possible to measure a person's lifetime exposure to radiation from various sources inside and outside the body. It is also puzzling that the standard has been set by the Food Safety Commission.

The commission was actually asked by the Ministry of Health, Labor and Welfare to determine a safety threshold for lifetime exposure to radiation from materials included in foodstuffs.

After radioactive contamination was discovered in vegetables and water following the disastrous accident at the Fukushima plant, the health ministry set provisional safety standards concerning radioactive elements in foods in March. The ministry then asked the panel to determine the appropriateness of the benchmarks.

But a working group of the commission found little scientific literature focusing solely on the health effects of radioactive materials contained in foods. The group reached the conclusion that it is impossible to make separate assessments for the health risks of internal and external exposure.

The 100-millisievert limit set by the panel is based on an assessment by the International Commission on Radiological Protection. According to the ICRP, there is solid scientific evidence indicating that exposure to radiation above this level carries a cancer risk.

The working group also concluded that special attention should be paid to the fact that children and fetuses are more vulnerable to radiation than adults, although it has not offered any specific figure.

The government plans to formalize the proposed radiation protection standard after soliciting opinions from the public.

But the health ministry has no idea how it can formulate safety standards for food based on this figure.

The ministry should not be blamed for that.

In fact, there is no section within the government that is dealing with issues related to health hazards posed by a combination of external and internal exposure to radiation.

The health ministry is responsible only for issues related to internal exposure due to contaminated foods, while the Ministry of Education, Culture, Sports, Science and Technology is in charge of problems of external exposure from sources like contaminated schoolyards.

This is because of the strictly compartmentalized structure of the government.

The government should first develop basic policies for assessing and reducing the effects of radiation exposure due to all kinds of sources, including those in the environment and foods. Then, ministries and agencies can come up with specific measures to tackle the challenge.

The ICRP's standards for radiation exposure in emergencies are based on the notion that higher-than-normal levels should be accepted in such situations and then efforts should be made to control overall exposure.

The government should take the implications of the Food Safety Commission's proposal seriously and map out its overarching policy concerning the issue as soon as possible.

--The Asahi Shimbun, Aug. 13