Wednesday, March 16, 2011
HOW RADIATION COULD CONTAMINATE JAPAN'S FOOD: LESSONS FROM CHERNOBYL
With the ongoing disaster in Japan on my mind, I spent some time today trying to find out about how radioactivity could affect Japan's agriculture and how long contamination could last. I looked to UN and other research done on the Chernobyl incident for answers, although hopefully, the amounts of radioactive materials released will not be as bad in the case of Japan. At present we simply don't know. Here are some potential lessons from Chernobyl for Japan's food production and consumption that emerge from these studies.
In the early months after the Chernobyl disaster in the Ukraine, food contaminated in areas with high radiation exposure was mainly due to radioiodine. It turned up in high levels in plants and grass and plant eating animals and their products (such as milk, including goat and sheep milk) and in fish in certain waters, with special risks for children and pregnant women. But iodine-131 is short lived. After a couple of months, most of it decayed. After that the main hazard for food crops was the uptake by root vegetables of radioisotopes from the soil (where rain had deposited it), especially the dangerous caesium.
What I found interesting in the Chernobyl case was that apparently the levels of radiocaesium in food crops and in animal feed were not just affected by how much of it floated around in an area and landed on the soil, but by factors such as the type of soil and type of agriculture and livestock management practices that area people used.
Problems persisted longer in the extensive type of agriculture system (think "traditional" or "subsistence") where the soil is not ploughed much, there is a lot of organic content, and where animals graze in open "natural" pastures. The Chernobyl case suggests that forest foods and animals grazing in forest and mountainous areas can retain high levels of radiocaesium for decades.
In sum, as I understand the findings (and I hope I have got it right) in the short term (about two months) the main food hazard in agriculture areas after radioactivity is radioiodine in fresh fruits and vegetables (e.g. leafy greens) growing above ground, and in milk and dairy products from area cattle. For the next couple of years or so after that, caesium contamination of root vegetables would be the main risk to avoid, particularly on organic farms and where traditional farming practices are still used. Over the still longer term , caesium contamination in milk, meat and forest products (wild mushrooms, berries and game) could continue to be risks.