The generation and evaluation of UICC asbestos clouds in animal exposure chambers

When carrying out animal inhalation experiments using UICC asbestos it was found necessary to modify the dust cloud generation technique described by Timbrell, to obtain a stable, well-dispersed cloud at concentrations from 1 to 10 mg/m3. The MRE gravimetric dust sampler type 113A recommended by Timbrell as a routine monitoring instrument, was found to undersample at high chrysotile concentrations, and an alternative system was developed using a vertical elutriator.

Fibre number counts of the clouds were obtained and correlated with mass concentrations. A Royco particle counter model 225 and Sibata digital dust indicator model AP.3 were tested, and their usefulness at the prevailing high concentrations assessed. Fibre length distributions for clouds of UICC chrysotile A, amosite and crocidolite asbestos are reported.