Review of the characterisation of hot particles released into the environment and pathways for intake of particles

Published data are reviewed on the physicochemical characteristics and biokinetic behaviour of radionuclides that may influence the calculation of radiation doses following their release into the environment after a nuclear accident or incident. Among the important parameters which can influence the assessment of dose coefficients (doses per unit intake), four main parameters can be measured: the particle size distribution of aerosols: the isotopic composition; the dissolution parameters such as in vitro dissolution rates or in vivo absorption parameters to blood, which are the most relevant in terms of inhalation; and the gastrointestinal absorption factor, f(1), for ingestion. Numerous data are available on the physicochemical properties of nuclear particles including isotopic and radioactive composition, observations from scanning electron microscopy, geometric diameter and particle size distribution. In contrast, very few data exist either on in vitro dissolution compared with solubility in biological systems or on the biokinetics of radionuclides in vivo. Some examples of in vivo experiments have been chosen as a methodological guide for future experiments and to demonstrate the importance of the effect of specific parameters, such as absorption characteristics on the assessment of dose coefficients.