Problems associated with the quantitative estimation of asbestos.

This Research Project is concerned with the application of X ray diffraction techniques to the Union Internationale Contre le Cancer (U.I.C.C.) standard reference samples of asbestos, (1) The experimental techniques adopted are based upon methods employed by Crable (2) and Crable and Knott (3). However, in the present work the samples examined have consisted of fibres in the respirable range (i.e. of lengths from 0.2mum to 200mum). The investigations were divided into three sections: 1) A study of the X ray diffraction patterns of the asbestos samples using both X ray diffractometer and powder camera. 2) An examination into the possible application of the two U.I.C.C. standard reference samples, Crocidolite and Anthophyllite, as internal standards in X ray analytical methods. 3) The examination of the X ray diffraction pattern of the dust collected from an asbestos worker's lungs and the use of the U.I.C.C. standards as internal and external standards. Experimental evidence is produced to show that absorption effects control the maximum Crocidolite content of the samples which can be used in X ray analysis. This is supported by theoretical considerations. The main conclusions which can be drawn from the work are that within specified limits, X ray diffraction techniques can allow quantitative analysis of asbestos in dust samples, and that the use of Anthophyllite and Crocidolite as internal or external standards in lung dust samples presents problems, which are not evident from the results obtained from the experiments on the U.I.C.C. samples. The work shows the need for further refinements of the X ray diffraction technique and the examination of many more lung samples.