NRPB-W40: Non-technical summary

Non-technical summary

Models are used to assess the radiation dose to man from radionuclides in the environment, whether from naturally-occurring radionuclides, authorised discharges or accidental releases. Some of these models use transfer factors (TFs), which are simply quotients of activities in the relevant media at equilibrium. For instance, the feed to milk TF is the activity concentration in milk divided by the daily intake. At equilibrium, this value will be constant. This review identified published research where such factors had been determined in order to arrive at average values for as many radionuclides as could be found; these were then compared with the current values used in the NRPB model FARMLAND, which is used to predict transfer along foodchains.

Nearly 300 individual references were reviewed, just over half of which were not suitable for one reason or another. Nearly 1000 records were obtained from the remainder. About 60% of these related to transfer to cows' milk, 16% to sheep or lamb meat, 5% each for beef and goat products, and the remainder for less than 5%. For many parameters, only a few datasets could be found, and opportunities for further research exist in those cases.

The average values calculated in the review were generally in good agreement with the default values currently used in the FARMLAND model for the important radionuclides and animals, and for most of the less important ones as well. For others, the current default values are higher than those reviewed. Whilst this would lead to higher estimates of dose than actually received, it is important that these over-estimates are not grossly excessive.

Last reviewed: 1 September 2009