- Dose conversion coefficients (DCCs) - participants were asked to estimate the unweighted absorbed dose rates for both internal and external exposure assuming an activity concentration of 1 Bq kg^−1^ in the organism or surrounding media, respectively. A selection of freshwater and terrestrial geometries proposed by the ICRP for their Reference Animal and Plants (RAPs) were used for the exercises. Estimates were made for seven radionuclides 3H, 14C, 60Co, 90Sr, 137Cs, 238U and 241Am) chosen to cover a range of energies and radiation types. The results of this exercise are described fully by Vives i Batlle et al (2007).
- Transfer - participants were required to estimate the whole-body activity concentration of eighteen radionuclides, in seven terrestrial organisms (grass/herb, shrub, earthworm, herbivorous mammal, carnivorous mammal, rodent, bird egg) and twelve freshwater organisms (phytoplankton,zooplankton, macrophyte, benthic mollusc, small benthic crustacean, large benthic crustacean, pelagic fish, benthic fish, fish egg, amphibian, duck and mammal) assuming an activity concentration of 1 Bq per unit (kg, L or m3) of media (soil, water or air, respectively). The results of this exercise are evaluated in Beresford et al. (2008).
- Perch Lake - located on the AECL Chalk River Laboratories site (Ontario), Perch Lake has received chronic, low-level inputs of a number of radionuclides since the 1950s. Participants were supplied with 90Sr, 3H, 60Co and 137Cs activity concentrations in water and sediments for selected years to allow the comparison of predictions of whole-body activity concentrations in a range of biota, including different fish species, aquatic mammals, plants, aquatic reptiles, amphibians and a range of invertebrate species. Unweighted internal and external absorbed dose rates were also estimated. The Perch Lake scenario is reported by Yankovich et al. (2010).
- Chernobyl exclusion zone - participants were provided with soil activity concentrations (90Sr, 137Cs, 241Am and Pu-isotopes) and requested to make predictions of whole-body activity concentrations, and internal and external unweighted absorbed dose rates. Results were compared to available data for a range of biota types including: graminaceous vegetation; invertebrates; birds; a wide range of mammal species (from small rodents to deer and carnivorous species) and amphibians. Results from thermoluminescent dosimeters attached to small mammals were also available allowing a comparison with predicted external gamma dose rates. This scenario is reported by Beresford et al. (2010).
Recommendations of the BWG
Whilst the need for a system to protect the environment from ionising radiation is now generally recognised many aspects including the discussion of protection goals, agreement of benchmark values and parameterisation of models applied in the work described here are still under development.