Iida, who is 35, forbids her children from entering the sea or into forests. She agonises over which foods to buy. But no matter what she does, she can’t completely protect her children from radiation. It even lurks in their urine.

“Maybe he’s being exposed through the school lunch,” she says, puzzling over why her nine-year-old son’s urine showed two-and-a-half times the concentration of caesium that hers did, when she takes such care shopping. “Or maybe it’s from the soil outside where he plays. Or is it because children have a faster metabolism, so he flushes more out? We don’t know.”

Iida is a public relations officer at Tarachine, a citizens’ lab in Fukushima, Japan, that tests for radioactive contamination released from the 2011 accident at the Fukushima Daiichi nuclear plant. Agricultural produce grown in the area is subject to government and supermarket testing, but Tarachine wants to provide people with an option to test anything, from foraged mushrooms to dust from their home. Iida tests anything unknown before feeding it to her four children. Recently, she threw out some rice she received as a present after finding its level of contamination – although 80 times lower than the government limit – unacceptably high. “My husband considered eating it ourselves, but it’s too much to cook two batches of rice for every meal. In the end we fed it to some seagulls.”

Tarachine is one of several citizen labs founded in the wake of the Tōhoku earthquake and tsunami on March 11, 2011, which obliterated a swathe of the country’s northwest coast and killed more than 18,000 people. The wave knocked out cooling systems at the Fukushima Daiichi nuclear plant, triggering a meltdown in three of the reactor cores and hydrogen explosions that sprayed radionuclides across the Fukushima prefecture. More than 160,000 people were forced to evacuate. A government decontamination programme has allowed evacuation orders to be lifted in many municipalities, but one zone is still off limits, with only short visits permitted.

Driven by a desire to find out precisely how much radiation there was in the environment and where, a group of volunteers launched Tarachine in Iwaki, a coastal city that escaped the worst of the radioactive plume and was not evacuated, through a crowdfunding campaign in November 2011. It is now registered as a non-profit organisation, and runs on donations.

In a windowless room controlled for temperature and humidity and dotted with screens showing graphs, two women sort and label samples, either collected by staff or sent in by the public: soil from back gardens, candied grasshoppers, seawater. In the beginning, mothers sent in litres of breastmilk. Tarachine initially charged a tenth of what a university lab would charge to make the testing accessible to as many people as possible; last year, they made it free.

To test for caesium-137, the main long-term contaminant released from the plant, staff finely chop samples and put them inside a gamma counter, a cylindrical grey machine that looks like a centrifuge. Tarachine’s machines are more accurate than the more commonly accessible measuring tools: at some public monitoring posts, shoppers can simply place their produce on top of a device to get a reading, but this can be heavily skewed by background radiation (waving a Geiger counter over food won’t give an accurate reading for the same reason). Tarachine tries to get as precise readings as possible; the lab’s machines give results to one decimal place, and they try to block out excess background radiation by placing bottles of water around the machines.

Measuring for strontium, a type of less penetrative beta radiation, is even more complicated: the food has to first be roasted to ash before being mixed with an acid and sifted. The whole process takes two to three days. Tarachine received training and advice from university radiation labs around the country, but the volunteers had to experiment with everyday food items that scientists had never tested. “There was no recipe like ‘Roast the leaf for two hours at so-and-so Celsius’, you know?” says Iida. “If it’s too burnt it’s no good. We also had to experiment with types of acid and how much of the acid to add.”

Japanese government standards for radiation are some of the most stringent in the world: the upper limit of radioactive caesium in food such as meat and vegetables is 100 becquerels per kilogram, compared with 1,250 in the European Union and 1,200 in the US (the becquerel unit measures how much ionizing radiation is released due to radioactive decay). Many supermarkets adhere to a tighter limit, proudly advertising that their produce contains less than 40 becquerels, or as few as 10. Tarachine aims for just 1 becquerel.

“How I think about it is, how much radiation was there in local rice before the accident? It was about 0.01 becquerel. So that’s what I want the standard to be,” says Iida. Continue reading →