Further studies of progressive massive fibrosis (PMF) among miners andex-miners.

The occurrence of progressive massive fibrosis (PMF) in coalminers has been shown to be related to age, dust exposure, physique and category of coalworkers’ simple pneumoconiosis (CW); and higher attack rates in ex-miners than miners have been explained by differences in CWP category, age and dust exposure. As part of a study of PMF of various radiographic types, occurrence of PMF in 4772 men over an approximately 10-year period (1960s–1970s) has been investigated further. The further work used new epidemiological readings of the 1960s radiographs by four of the IOM’s panel of experienced non-medically trained readers. It also used new readings of PMF, by two medically qualified readers, of all films for men for whom large opacities had been identified previously. The associations of PMF with CWP, age, physique and dust exposure were confirmed. The risks of PMF were again found to be higher in ex-miners than in miners, but the differences were not fully explained by differences in CWP category, age and dust exposure. A relationship between quartz exposure and PMF development was found in the readings of one reader, but this was not apparent using the readings of the second. Finally, higher risks of PMF were also apparent among men whose CW had progressed in the 10 years prior to the study period, suggesting a possible indirect effect of quartz exposure.