§ Mr. BoswellTo ask the Minister of Agriculture, Fisheries and Food what further assessment he has made of the effectiveness of the mark and release scheme in preventing radioactive sheep from entering the food chain; and if he will make a statement.
§ Mr. Donald ThompsonThe mark and release scheme permits sheep that have been live-monitored to leave the restricted areas. Those above 1,000 Bq/kg are marked with a distinctive paint mark to ensure that they are not slaughtered until restrictions on them are lifted. Sheep were marked blue between 28 September 1987 and 10 January 1988. Restrictions on blue-marked sheep were lifted on 1 June 1988.
Radioactivity levels in sheep fall at a rapid and steady rate once they have left the restricted area. The biological half life of the caesium in sheep grazing clean pasture is 10 days. Farmers outside the restricted area were therefore able to have blue-marked sheep remonitored and if they were no longer above the action level they were released from restriction by attaching a distinctive ear tag. It was not necessary to await a change of colour for such remonitoring to take place. 5,500 blue-marked sheep were remonitored; 33 were found to he above the action level in late 1987. These were subsequently remonitored and levels had fallen as expected. No blue-marked sheep have been found above the action level since January and the Ministry is entirely satisfied that no blue-marked sheep above the action level entered the food chain.