The UK's food regulator yesterday published three reports showing that sheep at the farms in Cumbria, Scotland and Wales still contain levels of radioactivity above safety limits.
the Food Standards Agency (FSA) is responsible for ensuring food safety by preventing products with unacceptable levels of radioactivity from entering the supply chain.
In 1986, an accident at the Chernobyl nuclear power plant in what is now the Ukraine released large quantities of radioactivity into the atmosphere. Some of the radioactivity, predominantly radiocaesium-137, was deposited in some upland areas of the UK, where sheep farming is the primary land-use.
Due to the particular chemical and physical properties of the peaty soil types present in the areas, the radiocaesium is still able to pass easily from soil to grass. The radiocaesium then accumulates in the sheep that feeds on the grass.
The FSA has used the Food and Environment Protection Act 1985 (FEPA) since 1986 to impose restrictions on the movement and sale of sheep exceeding the limit in certain parts of Cumbria, North Wales, Scotland and Northern Ireland.
Only sheep that have less than the maximum limit of 1,000 becquerels (a measure of radioactivity) per kilogram of radiocaesium are allowed to enter the food chain under the emergency orders in the FEPA.
Initially the restricted areas were large, but have been reduced substantially as levels of radioactivity have fallen. All restrictions were lifted in Northern Ireland in 2000, the FSA stated.
In 1986, almost 9000 farms were under these restrictions in the UK. Since then, the levels of radioactivity have fallen in some of the affected areas and the number of farms still under restriction in Cumbria, Scotland and Wales now stands at 374.
A management system known as the "mark and release: scheme operates in the restricted areas. Under this scheme, a farmer wishing to move sheep out of a restricted area can have them monitored to determine the level of radiocaesium.
Any sheep that exceed the working action level are marked with a dye and are not released from restrictions. Those that pass are allowed to enter the foodchain.
Based on a new survey results, the reports propose that none of the farms still under restriction in Cumbria and Wales should have their restrictions lifted in the near future. In Scotland, the results led to one farm being released from restrictions in January 2006.
The FSA plans further surveys so farms can be released from restrictions when the levels of radioactivity in sheep are within safety limits.