A sample of men working in the British coal industry in the 1950s has been followed up and examined 22 years later. The relations between lung function and individual cumulative exposure to respirable dust have been studied in 1867 men who were still working in the industry at the time of follow up and 2192 men who had left. Levels of forced expired volume in one second (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio at follow up were found to be inversely related to exposure to respirable dust after allowing for other factors, even in men without pneumoconiosis. The magnitude of this estimated effect was equivalent to a loss of 228 ml FEV1 in response to an exposure of 300 gh/m3, a moderately high exposure for this group. Ex-miners aged under 65 had worse lung function than miners on average, suggesting that ill health had encouraged some of these men to leave the industry. Whereas a more severe response to dust exposure among ex-miners under 65 was suggested, this difference could easily have arisen by chance. The presence of symptoms of chronic bronchitis was associated with reduced levels of lung function, however, and, additionally, ex-miners under 65 with chronic bronchitis showed a more severe response of the FVC to dust exposure than miners without these symptoms. Among these ex-miners with chronic bronchitis a small group of men who had taken other jobs showed a much more severe effect of dust exposure on their lung function than the average, likely in heavily exposed men to contribute importantly to disability. Men in this group who had given up smoking showed an even more severe effect of dust exposure, equivalent to a loss of 940 ml FEV1 in response to an exposure of 300 gh/m3. These results indicate that exposure to respirable dust can occasionally cause severe respiratory impairment in the absence of progressive massive fibrosis. Dust exposure was related to a parallel reduction of FEV1 and FVC, implying that the pathology of dust induced lung damage differs from that induced by smoking. This pattern of abnormality was shown by some non-smokers, whereas smokers and ex-smokers apparently severely affected by dust showed a classic obstructive pattern of abnormality with pronounced reduction of the FEV1/FVC ratio. These studies were based on men still at work in the coal industry; and, since ill-health may influence some men to leave their work, it has not been clear whether Acoepted 17 June 1985 the quantitative dust/disease relation estimated applied to all miners generally, or whether some men who had left the industry had suffered greater response to dust exposure than had been observed in working miners.The first aim of the present study was to confirm the previous finding of a relation between exposure to respirable dust and level of lung function, using a more representative group of British miners, better measures of dust exposure and of smoking habits, and a wider range of lung function measurements than before. The second and main aim was to examine whether men who left t...

Objectives-To describe the radiographic changes in coalworkers exposed to unusual concentrations of respirable quartz during the 1970s, and to relate these to exposure measurements. Methods-Men who had worked at one Scottish colliery during the 1970s were invited to a health survey. Chest radiographs were taken from 547 subjects. Classifications of these films under the International Labour Organisation (ILO) 1980 scheme were related, by logistic regression, to existing data on individual men's exposures to respirable dust and quartz. Results-Taking the median of the three readers' results on profusion of small opacities, 203 men (38%) showed progression of at least one profusion category on the 12 point scale, from the various 1970s surveys to the follow up in 1990-1. A total of 158 men (29%) had a profusion of at least 1/0, and 47 (8.6%) of at least 2/1 at the follow up survey. Large opacities were recorded as present by at least two readers for 14 (2.6%) of the men. Profusion of small opacities was strongly related to exposures experienced in the 1970s, and more strongly for quartz than for the nonquartz fraction of the dust. Estimates of risk are presented over the range of quartz exposures experienced. Conclusions-The quartz exposures experienced by some men at this colliery have caused considerable progression of radiographic abnormalities since exposure ended. The data accumulated oVer opportunities for further more detailed analyses to inform debate on occupational limits for quartz exposures, both in collieries and in other industries where there is exposure to quartz in mixed dust. (Occup Environ Med 1998;55:52-58) Keywords: silica; silicosis; coalworkers; exposureresponse; quartzThere is a shortage of reliable information on the risks of silicosis after exposure to respirable quartz, particularly as a component of respirable mixed dust. Epidemiological exposureresponse studies so far [1][2][3][4][5][6][7] give widely disparate estimates of risk, almost certainly because of deficiencies in the exposure data, 8 much of which is poorly suited, or was never intended, for the reliable estimation of risks.Some members of a colliery population were exposed, during a period in the 1970s, to unusually high concentrations of freshly cut quartz in mixed coalmine dust. The population's exposures to quartz dust had been measured in unique detail, for a substantial proportion of the men's working lives, and throughout the period when the critical exposures occurred. Health status was monitored at regular intervals while the population was exposed.We report on the results of a follow up survey of the respiratory health of survivors from this population. We describe the radiographic abnormalities which have developed, some of them severe; derive exposure-response relations for the risks of developing the silicotic abnormalities; and calculate preliminary risk predictions. THE COLLIERYIn the early 1950s the National Coal Board began the pneumoconiosis field research (PFR) programme, which has been the princ...

No abstract

). Thorax, 31,[158][159][160][161][162][163][164][165][166]. Distribution of plasma cell and other ceils containing immunoglobulin in the respiratory tract of normal man and class of immunoglobulin contained therein. The anatomical distribution of plasma cells and other cells containing immunoglobulin in the respiratory tract, and the relative proportions of the immunoglobulin classes, have been estimated on necropsy tissues from nine adult human subjects without respiratory disease, five non-smokers and four smokers, none of whom had cough or sputum. Cell counts on multiple sections stained by immunofluorescent methods for the presence of immunoglobulin were carried out on the upper trachea, main bronchus, and lower lobe bronchus.Cells containing immunoglobulin were found mostly in the submucous glands but were also present in the lamina propria of the tracheal and bronchial epithelium. These cells were present in the greatest concentration in the main bronchus and were always present in the lobar bronchus and, in most subjects, in the upper trachea. The cells were not always present round small bronchi and bronchioles and were virtually absent from alveolar walls.Cells containing IgA were much more numerous than those containing other immunoglobulin classes in all subjects except one, in whom IgG and IgE cells were equally numerous. Two subjects appeared to be significantly different from the rest. One nonsmoking subject had a marked deficiency of IgA cells at all sampling sites, and one smoker had a marked excess of IgA cells. In spite of these two subjects there was no significant difference between smokers and non-smokers except in the lobar bronchus where the smokers had significantly more IgA cells than the non-smokers.

. (1975). Thorax, 30,[436][437][438][439][440]. Nocturnal and morning asthma: its relationship to plasma corticosteroids and response to cortisol inftusion. Nocturnal and early morning breathlessness is a common and important symptom in asthmatic patients. Six patients in whom these symptoms were a major clinical problem have been studied by serial measurements of peak expiratory flow rate (PEFR) and plasma corticosteroids over two 24-hour periods. Although PEFR and plasma corticosteroids are lowest during the night or early morning, preventing the nocturnal fall in plasma corticosteroids by cortisol infusion did not prevent the fall in PEFR in five out of the six patients. The circadian rhythm of corticosteroid secretion does not appear to be the main cause of nocturnal and early morning asthma.