X-ray findings, lung function, and respiratory symptoms in black South African vermiculite workers.

Health effects have been documented among American vermiculite workers who mined and processed vermiculite contaminated with amphibole asbestos, viz., tremolite-actinolite. Workers mining and processing South Africa vermiculite (N = 172), which contains very little asbestos, underwent x-ray examination and lung function testing and completed a respiratory symptom questionnaire. The vermiculite workers were compared with other workers involved in the mining or refining of copper. Only two of the vermiculite workers showed evidence of small opacities of 1/0 or more (according to the ILO 1980 classification); lung function was comparable with the other groups of workers, and there was no excess of respiratory symptoms among the vermiculite workers. It is concluded that workers exposed to vermiculite that is minimally contaminated with asbestos are probably not at risk for pneumoconiosis, lung function impairment, or respiratory symptoms. It is likely that the health effects observed in other studies of vermiculite workers are the result of concomitant asbestos exposure. A risk of mesothelioma caused by the fiber content of the vermiculite cannot be excluded by this study.

[The forced expiration test from the pulmonary capacity usable in effort to the transit time]. / L'épreuve d'expiration forcée de la capacité pulmonaire utilisable à l'effort (CPUE) aux temps de transit.

Since Tiffeneau's days the forced expiration test used qualitatively and quantitatively has undergone numerous changes. FEV1 remains useful to diagnose bronchial obstruction, but other, more sensitive parameters have been introduced for epidemiological purposes. Following a review of the data provided by flow-volume curves, the authors discuss the pros and cons of its statistical analysis by the moment method, as expressed in the literature.

The timing of the forced vital capacity.

Based on analysis of more than 2,500 forced vital capacity (FVC) maneuvers, we examined 2 aspects of the standards for spirometry recommended by the 1977 Snowbird Workshop concerning the timing of the FVC maneuver. We compared the forced expiratory volume in one sec (FEV1) when timing was initiated by the back extrapolation method with FEV1 when timing was initiated by flow or volume threshold to determine whether the latter offered a reliable equivalent. Although the mean differences appear to be relatively small, because of variability in initiating expiratory effort, neither alternative is likely to offer a uniformly accurate numeric equivalent to backward extrapolation. We also measured the volume expired before the initiation of the timing as a per cent of FVC to determine whether 10 per cent was a reasonable limit to apply for acceptability of a test. Although 2 SD from the mean of 4.35 per cent were well within this limit, it appears that the technician's judgment of acceptability is sufficient in most cases.