Abstract
A procedure of quantitative chemical analysis on a crysotile fiber under electron microscopy was developed, and was successfully adopted to a study on its changing chemical composition in situ during its long lasting residence in the rat lung.
Lungs were obtained from the rats, which were sacrificed at 4 and 28 months after an intratracheal insuffiation of 10 mg of the crysotile. Routine paraffin sec-tions from those lungs were treated by means of carbon extraction technique and were submitted to analytical electron microscopy. Every single fiber identified under transmission EM was determined for the chemical composition by an simultaneous application of the X-ray microanalysis of energy dispersing type.
It was found that magnesium ion leached far faster than silica out of crysotile fibril during their residence in the lung tissue. It was also suggested that, in calculating the ratio of magnesium content to silica in the single fiber, rough estimation may also be possible on its past retention period in the lung tissue.
Preliminary determinations on the experimentally degradated crysotile in the test tube were also described. Results obtained from the X-ray Fluorescence Spec-trometry and the X-ray microanalysis of energy dispersive type were compared and discussed on possible application of the latter method to the crysotile fiber in vivo.
