Health minister Yoko Komiyama announced Friday that the
government will lower the allowable amount of radiation in food
products from 5 millisieverts per year to 1, but some experts are
puzzled.
Permanent limits for various categories of food will be set
based on recommendations submitted Thursday by the government's
food panel.
The current limit of 500 becquerels per kilogram of radiation
for meat, fish and vegetables is also expected to be lowered by
about one-fifth in April.
Citing findings from various studies, the food safety panel
concluded Thursday that a cumulative dose of 100 millisieverts or
more throughout one's lifetime poses significant health risks.
But experts question the focus solely on internal exposure from
food and drink, while ignoring external exposure from radioactive
materials, such as fallout on the ground, roofs and in ditches.
"I can't think of a reason why they decided to omit external
exposure as a factor in the proposal this time," said Dr. Eisuke
Matsui, who heads the Gifu Environmental Medicine Research
Institute.
The radiology expert noted that while consuming food
contaminated with radiation is a far bigger risk to human health
than being exposed to radiation from the environment, it does not
mean it can be disregarded.
"Think of the children in the cities of Fukushima or Minamisoma,
where there is a relatively high level of radiation in the
environment," Matsui said. "Any guideline on radiation should
consider the total exposure and not only the limit of contaminated
food one can consume."
According to the International Commission on Radiological
Protection, a cumulative dose of 100 millisieverts increases the
risk of dying from cancer by 0.5 percent. An organization of
scientists, the ICRP's recommendations serve as the basis for
radiation regulations of many developed countries, including
Japan.
The current limits for food and drink were set on a provisional
basis soon after the nuclear crisis broke out in March at the
troubled Fukushima nuclear power plant.
In July the same panel proposed in a preparatory report that 100
millisieverts be the combined limit of both internal and external
exposure to radiation.
Questioned by reporters about the decision to drop external
exposure from consideration, panel Chairwoman Naoko Koizumi offered
no clear explanation.
Members of the panel, consisting of independent experts,
asserted fallout across eastern parts of the country from the March
meltdowns at the Fukushima No. 1 nuclear plant did not dramatically
increase the risk from external exposure.
Koizumi also noted that other branches of the government should
conduct studies on the matter, not just the food safety panel.
There are few studies of the effects of low-level radiation for
extended periods, a key subject of debate among experts for
years.
One study cited by the panel to explain the 100-millisievert
regulation looked at cancer rates among survivors of one-time
exposure to high levels of radiation, such as in the nuclear
bombings of Hiroshima and Nagasaki in 1945.
Radiology expert Matsui argued that the government should make
certain of the facts before advancing policies.
"Personally, I think the cumulative 100-millisievert limit is
too high, whether it is only for internal exposure to radiation or
not. For children, I think it should be at least one-tenth of
that," he said.