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radiation

A woman shops for fruit at a Japanese department store in Hong Kong March 21, 2011.

Imagine a world in which you scan farmers' market purchases through a radiation detector to know whether they are safe to eat and your milk comes not only pasteurized but specially processed to break down radioactive compounds.

You purge mushrooms from your diet because they act like sponges for nuclear detritus, swear off game animals (they might consume mushrooms and other wild forage) and avoid digging too deep when planting your garden - one too many feet down and you'll be planting tomatoes in contaminated soil you deliberately buried there because, well, that's what the experts say to do when nuclear waste rains down on land people need to use to grow food.

These remain the odd realities of daily life for some people who live in the widespread areas affected by the 1986 Chernobyl disaster, history's worst nuclear accident.

It is impossible, at this point, to forecast whether people living in the vicinity of the Tokyo Electric Power Co.'s troubled reactors in northern Japan will face anything comparable.

The future of agriculture in the vegetable-growing region hangs in limbo while the government scrambles to secure a more precise reading on how widespread radioactive contamination is and what elements are present. Iodine-131 and cesium-137 are feared to have been released. While both can cause cancer if ingested - most likely after having settled, dust-like, on food crops - iodine-131 breaks down over the span of several weeks. Cesium-137 has a half life of 30 years, meaning it could take decades to dissipate.

Leafy vegetables, forage crops and the livestock that consume them are the most likely points for the radioactive elements to enter the food chain. On Saturday, Japanese government officials announced they had discovered higher-than-normal radioactivity in spinach and milk products at farms up to 145 kilometres from the power plants.

The announcement was paired with pleas for consumers to stay calm and assurances that ingesting small amounts of food containing higher levels of radioactive material will not lead to a heightened risk of developing cancer. However, on Monday, Japan moved to block more tainted food from reaching consumers. Shipments of spinach and rapeseed have been frozen in Fukushima prefecture as well as neighbouring Ibaraki, Tochigi and Gunma. Sales of raw milk have also been banned.

While Japan imports most of its food - the country is the largest food importer in the world - nearly 80 per cent of vegetables sold in the country are grown domestically. Fukushima is known for its vegetable production - spinach, asparagus, radishes, tomatoes and cucumbers.

Fred Mettler, a professor emeritus of radiology at the University of New Mexico who investigated the health effects of Chernobyl, said a number of agricultural "countermeasures" have been taken in the region affected by the 1986 accident to ensure production is safe.

"A lot of plants grow in the top few inches of soil, so they have, in some places, done deep plowing to push cesium down under where roots don't get at it very much," he said.

In cases where the soil has a high clay content, the clay will hold onto the cesium and prevent it from seeping into plant roots. Sandy soils, though, can trade cesium back and forth with plants for years.

To prevent livestock from ingesting contaminated grass and plants, animals can be kept indoors and fed clean feed produced in a non-affected region. While milk produced by affected animals is not safe to drink, it can be processed into safe products.

"One can turn it into cheese and just wait," Dr. Mettler said. "The iodine will go away."

Ward Whicker, a retired radioecologist who spent his career at Colorado State University studying risk levels related to radioactivity in the environment, said levels of cesium will determine whether there is a need to establish an agricultural no-go zone in Japan.

He noted that international guidelines on how much exposure to radioactivity is acceptable are extremely conservative.

"These numbers are based on trying to achieve a very low risk in developing cancer in the human population. We're talking generally about risks that are less than one in 10,000 of getting cancer in your lifetime," Dr. Whicker said.

"Typical guidelines for the amount of a given radionuclide in food are usually set up with the assumption the person would consume the material every day for a year."

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