When Greenpeace opened a 2kg bag containing topsoil at a Tokyo press club recently, a Geiger counter pointing accusingly at the earth screamed vigorously.
To highlight the radiation danger that schools close to the stricken nuclear plants at Fukushima may now be facing, the environmental pressure group had brought the soil from one of their playgrounds.
The Japanese government, however, is having none of it. It insists the schools beyond the evacuation zone are safe and are to remain open, especially now many have scraped the topsoil from their dirt-crowned playgrounds.
However, outside activities are still not an option as children are advised by officials to cover up and stay inside as much as possible.
Greenpeace is not alone in considering radiation levels just outside the evacuation zone too high for children.
Physicians for Social Responsibility, an American non-governmental organisation and anti-nuclear campaign group, has condemned as "unconscionable" the Japanese government's safety standards on radiation levels at schools in Fukushima prefecture.
"Children are much more vulnerable than adults to the effects of radiation," it claims.
When a top adviser to the government on radiation levels suddenly quit a few weeks ago, he added his doubts to this growing chorus. "I just cannot tolerate requiring such figures for infants, toddlers and primary-school pupils," he tearfully told journalists at another press conference, referring to official ruling on safe radiation levels.
Teachers and officials at local level say they are now at the centre of this tug-of-war.
"If we measure radiation and find they are under official guidelines for radiation levels in schools then we simply have to reopen," said one school governor in Fukushima. "Parents want the schools moved."
Given the central government's previous track record over the safety of the Fukushima plants themselves, many parents remain sceptical.
Notwithstanding concerns over radiation, just getting education back to normal in the Fukushima region is going to be a hard slog.
In all, 169 public schools in the disaster zone have been closed or forced to relocate temporarily. Of that total, about 85 per cent have been able to restart ad-hoc lessons by borrowing classrooms at other schools or moving to schools that had closed before the earthquake. Class numbers are, of course, smaller now because so many children died in the disaster, but others, too, have quit school and moved elsewhere.
Japan's education ministry says about 10,000 children have moved from Fukushima prefecture following the 11 March earthquake and the ensuing crisis at the Fukushima Daiichi nuclear power plant.
The dread felt in the region is summed up in a letter "addressed to the world" from mother and Fukushima city resident Tomoko Hatsuzawa: "We live 60 kilometres (37 miles) from the plant and our homes have been contaminated beyond levels seen at Chernobyl. The Caesium-137 they are finding in the soil will be here for 30 years. But the government will not help us. They tell us to stay put. They tell our kids to put on masks and hats and keep going to school."