To eat or not? Japan tests Fukushima fish daily to quell safety concerns

Researchers work out of a laboratory in the city of Tagajo in Miyagi Prefecture, first getting fish samples from the water about 5 km (3.1 miles) away from the wrecked Fukushima nuclear plant before collecting tritium through a series of combustion devices to measure the level of radiation.

The result is published on the website of Japan's fisheries agency every day except for days when setting up nets to catch fish is impossible due to bad weather. So far, the agency has not found fish that contained detectable levels of the radioactive isotope tritium.

"We are conducting the tests (on fish) and releasing the results properly so that it can help people feel assured," said Akira Matsumoto, a researcher at the Marine Ecology Research Institute.

The reputation of Japan's fishing industry has taken a hit since the release of the treated water, a move strongly opposed by neighbouring countries. China has currently suspended imports of all aquatic products originating from Japan.

Local wholesalers at a bustling fish market in Sendai city, located approximately 110 km (68.3 miles) north of the stricken nuclear plant, say they trust the test results and hope it can help build customer confidence over food safety.

"I don't want people to question whether we should eat the seafood which China has completely banned. That's why we post the daily testing results at the market to show that it's safe," said Katsufumi Ishimori, vice president of Sendai Suisan Company, a fish wholesaler.

The operator of the wrecked plant Tokyo Electric Power Company (TEPCO) filters most radioactive elements out of the water, but it dilutes tritium, an isotope of hydrogen, which is difficult to separate from water.

University of Portsmouth Professor Jim Smith said the test results were in line with what he would expect, although he cautioned that the concentration of tritium in the water being released was not yet at the maximum planned level.

Tritium is a radioactive form of hydrogen that occurs both naturally and as a byproduct of nuclear power plants. It appears most commonly in the form of "tritiated water", where a tritium atom replaces one of the two hydrogen atoms that bind with an oxygen atom to form water. This makes it very difficult to remove.

Smith, who has studied the impact of radiation on aquatic life around the site of the Chernobyl nuclear disaster, added that the tritiated water's similarity to ordinary water meant that it would not accumulate — or "biomagnify" — in the bodies of fish.

The release of the first 7,800 cubic metres of treated water, equivalent to about three Olympic pools, will take about 17 days. It is estimated it will take about 30 years to release it all.