Distribution and characteristics of amphibole asbestos fibres, measured with the light microscope, in the left lung of an insulation worker
Occupational and Environmental Medicine
ABSTRACr Concentrations of uncoated and coated amphibole fibres were measured postmortem in samples taken from the periphery of both upper and lower lobes of the left lung of an insulation worker. Similar measurements were made on a more limited range of samples from elsewhere in the lung and on a hilar lymph node. The mean concentration of uncoated fibres in the upper lobe was twice that in the lower. Significant differences were observed in the mean concentration of uncoated fibres in
... d fibres in different regions of the periphery, the diaphragmatic region having the lowest value. Variations in the concentrations of both uncoated and coated fibres in the costal region of the lower lobe may have been related to the effect of rib structures on ventilation. Concentrations of fibrous and non-fibrous dust were well correlated in the peripheral samples. The length distributions of uncoated and coated fibres were also measured and differences detected in fibres from the various regions of the lung. This work emphasises the care required in sampling lung tissue in order to obtain representative material for the determination of fibre concentration. Although many workers have measured concentrations of asbestos fibres in samples of human lung postmortem, few studies have been performed of variations in the concentrations and characteristics of asbestos fibres within a single lung. Sebastien et all compared the concentrations of fibres in the central and peripheral regions of upper and lower lobes of lungs using both optical and transmission electron microscopy. For asbestos workers with heavy exposure, they found that fibre concentrations were greater in the upper lobe but the difference was not apparent in a second group with less exposure to asbestos. In the latter an accumulation of asbestos fibres, especially of chrysotile, was shown in peripheral areas. In a more recent paper Sebastien et a12 compared the concentrations of amphibole and chrysotile fibres in samples of tissue from the parietal pleura and parenchyma of a series of lung samples using transmission electron microscopy. This study showed that there was no correlation between the concentrations of fibres in the two regions but confirmed their earlier observation that the proportion of chrysotile fibres was greater at the periphery of the lung.