Pulmonary retention on inhaled particles in man

Knowledge of a toxic material's behaviour relative to that of the inert particles in animals and the behaviour of the inert particles in man provide a basis for predicting how the toxic material will behave in man. A study was made of non-smoking volunteers who inhaled relatively inert 1 or 4 μm particles labelled with 85Sr or 88Y respectively and the pulmonary retention was followed for a year by external counting. The results have provided a sounder basis for modelling the pulmonary retention of relatively insoluble materials than was hitherto available and will quantify the range of retention times which occur for a given material as a result of particle size effects and inter-subject variation. The parameters which would now be chosen to represent pulmonary retention are different from those included in the ICRP lung model but, in view of the uncertainties in the relationship between dose and intake, the ICRP model gives adequate results within its specified range of application. (U.K.)