Abstract

The relations of lung function and chest radiographic appearances with exposure to inspirable dust were examined in 634 workers in five wool textile mills in west Yorkshire, randomly selected to represent fully the range of current exposures to wool mill dust. Most of these workers could be categorised into three large sex and ethnic groups; European men, Asian men, and Asian women. Exposures to inspirable dust had been measured at a previous survey and time spent in current job, and in the industry were used as surrogates for lifetime cumulative exposures. Chest radiographs were interpreted on the International Labour Office (ILO) scale by three medically qualified readers, and the results combined. Profusions of small opacities of 0/1 on the ILO scale, or greater, were present in only 6% of the population, and were not positively associated with current exposure to wool mill dust, or duration of exposure. In general, statistically significant relations between exposure and lung function indices were not found, with the exception of an inverse relation between the forced expiratory volume/forced vital capacity ratio and dust concentration in European women. A suggestive but not statistically significant inverse relation between FVC and current dust concentration was seen in Asian men. Substantial differences were found between mills in mean values of lung function variables after adjustment for other factors but these were not apparently related to the differences in dust concentrations between these mills. Dyeworkers and wool scourers (mostly European men in relatively dust free jobs) on average experienced an FEV1 251 ml lower than other workers when age, height, smoking habits, and occupational factors had been taken into account. Twenty four per cent of the workforce responded to intracutaneous application of one or more common allergens (weal diameter at least 4 mm), only 12 (7.9%) of these responding to wool extracts. Atopic subjects did not appear to have an increased susceptibility to the effects of inspirable wool dust on lung function. These studies suggest that exposure to wool mill dust may cause functional impairment in some workers but there is little indication from these data of frequent or severe dust related functional deficits. More detailed estimates of cumulative dust exposure by reconstruction of exposure histories might clarify associations between exposure to dust and lung function. These chest radiographic findings provide no evidence that exposure to wool mill dust is related to lung fibrosis.