Irregularly shaped small shadows on chest radiographs, dust exposure, and lung function in coalworkers' pneumoconiosis.

Abstract

The predominant shapes of small opacities on the chest radiographs of 895 British coalminers have been studied. The aims were to determine whether irregular (as distinct from rounded) small opacities can be identified reproducibly, whether their occurrence is related to dust exposure, and whether they are associated with excess prevalence of respiratory symptoms or impairments of lung function. Six of the doctors responsible for regular radiological surveys of all British coalminers each classified all 895 radiographs twice and independently, using the International Labour Organisation's 1980 classification system. The majority view was that 39 films showed predominantly irregular small opacities, 131 showed predominantly small rounded opacities, and 587 showed no small opacities. Readers' opinions varied about the presence and shapes of shadows on the other 138 films. In general, consistency between readers (and within readers on repeated viewings) was satisfactory. The occurrence and profusion of irregular shadows were related significantly both to the men's ages and additionally to their cumulative exposure to respirable coalmine dust as determined from 15 years' dust monitoring close to where the miners had worked. For any given level of exposure, the average level of profusion of the small irregular opacities was less than the corresponding profusion of small rounded opacities. The prevalence rates of chronic cough and phlegm, and of breathlessness, were higher in those with small irregular opacities than in those with no small opacities (category 0/0), but the differences were not statistically significant after adjustment for other factors including smoking habits. The presence of irregular (but not rounded) small shadows was associated with an impairment in respiratory function averaging about 190 ml deficits in both FEVy and FVC. These deficits were not explicable in terms of the men's ages, body sizes, and smoking habits and they were in addition to the lung function losses attributable to the miners' dust exposure as such. It is concluded that the presence and profusion of small irregular opacities should be taken into consideration when assessing the severity of coalworkers' simple pneumoconiosis.The International Labour Organisation's (ILO) ever, also occur on the chest radiographs of coalclassification of the chest radiographic appearances of miners,4 and the frequency of their occurrence has pneumoconiosis distinguishes between small opacities been related -to years worked underground,5 6 sugthat are rounded in shape and those that are irregu-gesting that they, in addition to rounded opacities, lar.1 Present estimates of the risk of coalworkers' sim-might result from dust exposure. Irregular opacities ple pneumoconiosis in relation to respirable dust may also have different clinical implications from exposure are based on studies in which the criterion those of rounded opacities, in that the former have for pneumoconiosis has been the presence of small been related to reduced lung function67 and to...

Prevalence of pneumoconiosis and its relationship to dust exposure in a cohort of U.S. Bituminous coal miners and ex‐miners

“…Even after taking the standard error for this figure of about 0.8% into account, there is an apparent discrepancy with the figure of 5% predicted in the present report. However, the 5% prediction agrees well with a prevalence predicted for men age 60 years with zero dust exposure obtainable from interpolation of Figure 2 of Collins et al [1988]. This indicates a 5% prevalence for category 0/1 or greater small irregular opacities (where, in fact, most [90%] of the x-rays were classified as 1/0 or greater).…”

Radiographic outcomes among South African coal miners

“…This is in contrast to the findings in some recent studies, which have shown associations between simple pneumoconiosis and various respiratory symptoms, while controlling for dust exposure and smoking (Collins et al 1988;Wang et al 1999).…”

“…The association of simple CWP with decrements in pulmonary function, symptoms, and disability is less clear and more controversial, with several early studies reporting no significant association between CWP and respiratory impairment (Cochrane and Higgins 1961;Morgan et al 1972;Hankinson et al 1975). In contrast, later studies have shown significant relationships between CWP (and specific opacity types) and lung function outcomes (Collins et al 1988;Zhicheng 1986;Wang et al 1999).…”

Lung function decrease in relation to pneumoconiosis and exposure to quartz‐containing dust in construction workers

“…In coal miners [Amandus et al, 1976] the presence of irregular opacities was associated with impairment in respiratory function. Deficits of about 190 ml in both FEV 1 and FVC were observed [Collins et al, 1988], in addition to the lung function losses attributable to the miners dust exposure. We found no association between respiratory symptoms and radiographic abnormalities among the construction workers.…”