Radioactive cesium registering some 20,000 becquerels per kilogram has been found in worms 20 kilometers from the damaged Fukushima No. 1 nuclear plant.

The cesium was detected by a team including Motohiro Hasegawa, chief researcher in soil zoology at Japan’s Forestry and Forest Products Research Institute. Worms are a source of food for many wild animals, and it is feared that radiation could gradually accumulate in the bodies of animals throughout the food chain.

The research team’s findings will be announced at a meeting of the Ecological Society of Japan, to commence in the Shiga Prefecture city of Otsu on March 17.

Researchers dug up between 40 and 100 worms in national forests in the Fukushima Prefecture village of Kawauchi, which lies partly in the exclusion zone around the nuclear plant; the village of Otama, located 60 kilometers from the plant; and the town of Tadami, about 150 kilometers from the plant, between late August and late September last year.

The worms in Kawauchi registered 20,000 becquerels per kilogram of radiation. In Otama the level was around 1,000 becquerels per kilogram, while in Tadami 290 becquerels per kilogram was recorded.

Copyright © 2012 Mainichi Daily News
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Fukushima — Earthworms collected in Kawauchi, a village near the Fukushima No. 1 nuclear plant, have cesium levels averaging some 20,000 becquerels per kilogram, government researchers said.

The finding indicates the radioactive substance “may accumulate in other animals through the food chain,” Motohiro Hasegawa, senior researcher at the Forestry and Forest Products Research Institute, said Monday, noting earthworms are eaten by birds, boars and other wild animals.

Last August and September, Hasegawa and other researchers collected earthworms in Kawauchi, 20 km from the crippled power plant; Otama, 60 km from the plant; and Tadami, 150 km away.

The researchers analyzed average cesium levels in five earthworms gathered in each of the three locations. Worms from Otama were found to have 1,000 becquerels of cesium and those from Tadami had 300 becquerels, compared with the government's allowable limit of 500 becquerels for human exposure.

Fallen leaves exposed to fallout decompose in the soil before being consumed by earthworms, the researchers said, explaining how the cesium contamination spreads.

Cesium levels in the soil where earthworms were collected stood at some 1.38 million becquerels per square meter in Kawauchi, 80,000 to 120,000 becquerels in Otama and 20,000 becquerels in Tadami, they said.

Copyright © 2012 Japan Times Online
Reprinted for Fair Use Only.