nuclear-news

Seikatsu Club, a mail-order food delivery co-op, maintains an online database that includes more than 700,000 results of radiation tests on food items. Page views have fallen to about one-tenth of their peak in 2012, said Hiroshi Tsuchida, a quality management division chief with the co-op, but there are people who still visit the site almost daily.

“For such members, we are continuing testing and disclosing all the data on our website,” Tsuchida told The Japan Times. “In Ukraine, there are screening devices at markets where people check food even today, nearly 30 years since the (start of the Chernobyl) nuclear disaster. I believe we should do the same.”

Despite the lingering fears, however, overall contamination levels of farm produce and seafood from Fukushima and neighboring prefectures have declined significantly……..

But concern remains over fish, wild vegetables and wild game. Between April 1 last year and March 1, around 292,000 such samples were tested for radioactive cesium and 502, or 0.17 percent, exceeded the safe threshold, the health ministry said. In fiscal 2012, that ratio stood at 0.85 percent.

Wild vegetables, wild game, mushrooms, freshwater fish and bottom-dwelling ocean fish made up most of the contaminated food that exceeded the threshold over the past year, and was thus banned from shipment.

In February, wild boar meat from Fukushima Prefecture was found to contain 15,000 becquerels of cesium per kilogram, the highest figure since last April 1.

Highly contaminated wild game was also found in Miyagi, Iwate, Ibaraki, Tochigi, Gunma, Niigata and Saitama prefectures, including wild boar meat from Miyagi that contained 1,300 becquerels of cesium per kilogram and deer meat from Saitama that contained 530 becquerels of cesium per kilogram, according to government data.

As for mushrooms and wild vegetables, samples from 11 prefectures, including Fukushima, Yamanashi, Nagano and Shizuoka, exceeded the threshold between April 1 last year and March 1, according to the data.

The threshold of 100 becquerels per kilogram is intended to curb the total internal exposure to cesium from food to less than 1 millisievert per year.

Cumulative exposure of 100 millisieverts would increase the chance of death by cancer by 0.5 percent, according to the International Commission on Radiological Protection…….

The decline in contamination has been very slow among bottom fish, including karei flat fish and ainame greenling caught off Fukushima. The same is true of freshwater fish, including iwana, caught from rivers, lakes and ponds in Fukushima, Miyagi, Tochigi, Gunma and Chiba prefectures.

Toyoji Kaneko, a professor of aquatic bioscience at the University of Tokyo, said that in a pond, for example, radioactive cesium that accumulated in the water and soil and pond-bed would have no outlet and thus would tend to remain there. The fish would ingest the isotope, expel it and ingest it all over again, he said.

To reduce radioactive contamination, some suggest removing the highly contaminated surface soil at the bottom of ponds, lakes and river mouths. But the removal process would only stir up more radioactive substances in the water and dirt, Kaneko said, and there would be no way to dispose of such residue. A realistic option would be to leave the sites alone and wait for the cesium to decay, he said.

Jota Kanda, a professor of chemical oceanography at Tokyo University of Marine Science and Technology, said that in the case of bottom fish, the route of their contamination has yet to be established. Some experts believe the bottom fish become contaminated by eating radioactive matter on the seabed, while others note that such fish have a slow biological half-life, which is usually around 50 days for a marine fish……..

At the latest announcement by Tepco that radioactive rainwater has been running into the ocean since last spring has devastated local fishermen, further damaging the image of fish from Fukushima…….http://www.japantimes.co.jp/news/2015/03/12/national/produce-worries-easing-fish-wild-foods-still-problem-wake-fukushima-meltdowns/#.VQYTsdKUcnk