Three sheep were vaccinated with two doses of 3 Krad-irradiated cryopreserved Schistosoma bovis schistosomula containing 20,000 and 17,000 organisms respectively, injected intramusculary 23 days apart after storage in liquid nitrogen for between 9 and 46 days. A challenge of 5360 S. bovis cercariae was administered percutaneously approximately four weeks after the last vaccine dose to these animals and to three controls. Post-challenge the vaccinated animals gained significantly more weight (27%v.9%), produceed fewer eggs in their facces, showed a smaller reduction in PCV values (–18%v, –27%) and were over-all in better condition than control animals . At perfusion 49·1% fewer adult worms were found in the vaccinated sheep than in controls. The tissue egg burdens were similar in both groups. Histopathologically both groups were similar except that fewer and smaller egg lesions were observed in the livers of vaccinated animals.

Authorised discharges of radionuclides into sewers can result in contamination of the sludge, and so provide a pathway by which radionuclides can enter the foodchain. Specific data on the uptake of radionuclides from sludge amended land into crops is scarce. A study has been undertaken to generate data on tritium uptake by crops grown in soil amended with tritium contaminated sewage sludge using a range of soil types and crops common to the UK. The study was performed over two years. The concentration of tritium in soil fell throughout the study. It was therefore not possible to quantify individual soil to crop transfer in terms of conventional concentration ratios. Instead, an aggregated transfer quotient was estimated relating the concentration in the edible part of the crop in Bq kg-1 to the original amount of activity applied to the soil in Bq m-2. The values obtained were broadly similar at for all crop and soil types studied, being about 2 10-4 m2 kg-1. The observed values depend on factors such as temperature and rainfall, and so they should not be used in generalised radiological assessments. They are however indicative of the small amounts of tritium transferred to crops from amended soil.

Following the confirmation that Mr Litvinenko had received a large dose of 210Po, the Health Protection Agency began to prepare for public health monitoring of potentially contaminated people. Alpha counting of urine was the only practicable means of monitoring exposure. As the incident developed it became apparent that the number of samples would be likely to exceed the HPA's capacity. Therefore other UK laboratories were contacted and several agreed to assist. To validate the analyses each potential collaborator analysed a cross check sample that was the remainder from 24 hour samples that had already been measured at the HPA. The results were in good agreement. In the first four weeks of the programme, about 600 samples were collected and all were analysed using the resources in the UK. Later, the quality assurance exercise was extended to include laboratories in the UK and abroad that could potentially become involved in the analysis of samples arising from the incident. The factors underlying the success of the programme are set out. These included having a well founded Quality Assurance system in place during normal circumstances and having pre-existing links at the appropriate working level with other laboratories in the UK and abroad.