Chrysotile asbestos can be selectively stained with fluorochrome Coriphosphine O. The fluorescent staining technique positively distinguishes chrysotile from amosite, crocidolite and from man-made mineral fibers, like glass wool. As ubiquitous urban particulates do not interfere, the staining method allows the presumptive identification of asbestos fibers by light (fluorescent) microscopy in presence of a large excess of non-asbestos particles or fibers. Sometimes a slight interference from antigorite, a parent mineral of asbestos occurs. Investigations are in progress to establish if the few fluorescent points observed for this mineral may in fact correspond to asbestos fibers, in which case a link between fluorochrome uptake and physiological behaviour might be further sought. The current practice of sampling asbestos in occupational air, where asbestos represents a significant fraction of the particulates, is by collecting dust on organic membranes, mostly Nucleopore. The dust deposit is counted using phase contrast microscopy. Under these conditions, when asbestos is relatively abundant and overall samples of a few hundred micrograms can be collected, gravimetric evaluation using X-ray diffraction techniques is also possible. © 1979.
