§ Mr. Donald Thompson
[pursuant to his reply, 13 November 1987]: A total of 686 sheep from 29 flocks have now been monitored as part of the current intensive exercise in west Yorkshire. Confirmatory analysis has revealed that meat samples from three ewes taken from a flock grazing the moorland near Grassington have yielded levels of radiocaesium of 1222, 1295 and 980 becquerels/kilogram respectively. These results showed that two of the ewes were thus about the action level of 1000 bq/kg for lambs which does carry with it a very large safety margin and is not itself a safety level.
This further close monitoring of live sheep in the area will continue to determine, as seems possible, whether these higher levels are confined to this flock or a very small area.
The present special monitoring exercise in Yorkshire is being carried out in response to public concern that heavy rainfall in the area when the Chernobyl plume might have been passing overhead caused deposition of radioactive material. The present exercise is thus in the nature of a double check on the comprehensive national monitoring that we did last year which did not indicate any particularly high levels in Yorkshire but it is being done in the light of new information on rainfall which has recently been brought to our attention.
The results of the present exercise so far do not lead us to any different conclusion from that we had taken earlier that there is no risk to food supplies. The sheep for which we have the above results are breeding ewes. Lambs or other sheep likely to be going to slaughter have all been found to have levels of radioactivity well below the action level. These lambs or sheep have all been in the lower pastures. I understand that it is normal husbandry practice in this part of Yorkshire to finish lambs or sheep that may have been on the moorland on the lower pastures. This does suggest therefore that there has not been an earlier problem with radiocaesium in lambs that have gone for slaughter that has gone undetected. Together with the low results on vegetation I am thus satisfied that the general public in the area have not been exposed to undue levels of radioactivity in their diet.
The flock from which the three sheep were taken is being closely checked and arrangements are being made to ensure that any movements out of the flock are properly controlled.