Implications of the dosimetric model for the respiratory system on limits for intakes of radionuclides by workers (ICRP Publication 30)

A number of problems with the ICRP Dosimetric Model for the Respiratory System are discussed:- the assumption that the nasopharyngeal (N-P) region can be ignored, despite considerable evidence of significant retention in the N-P region and of pathological effects, treatment of the tracheobronchial tree (T-B), the pulmonary (P) region and the pulmonary lymph nodes (PLN) as one combined organ for calculating dose, the lack of deposition estimates for very small particles ( <0.1 μm dia.) and the use of a probit scale for percentage deposition, use of the aerodynamic equivalent diameter of particles beyond the range of applicability of the model and the desirability of defining an appropriate 'equivalent deposition diameter' suitable for the whole range of particle sizes of interest, treatment of components of inhaled mixtures as if they are independent in regard to both deposition and clearance characteristics, limitations of the currently used rigid solubility classifications (D, W or Y) of inorganic compounds in estimating retention and disposition of deposited particles. (author)