Decreasing Prevalence of Pleural Calcifications Among Metsovites With Nonoccupational Asbestos Exposure: Discussion
Comparisons concerning the prevalence of PCs according to age group show that it was significantly lower in the present study for the age groups 30 to 39 years (p < 0.001), 40 to 49 years (p < 0.01), and 50 to 59 years (p < 0.01). The corresponding differences for the older groups (ie, those 60 to 69 and > 70 years) were not significant (p > 0.05). The youngest person with PCs in the present study was 42 years old vs 29 years old during the study from 1978 to 1982. It should be highlighted that no PCs were observed in the group that 30 to 39 years old in the present study, while in the former study 6 of 21 Metsovites of the same age had PCs. The overall prevalence of PCs, although lower now, is not significantly different from that of 1978 to 1982 (178 of 307 persons [58.0%] vs 129 of 214 persons [60.3%], respectively; p > 0.05). Nevertheless, in the old study most individuals (63.1%) were < 60 years old, while in the present study that age group constitutes the minority (63.1% vs 32.65, respectively; p < 0.001). Source
Pleural plaques are the most common manifestation of asbestos exposure. They are often calcified and are thus easier seen on CXRs, even those of poor quality.’ The surprisingly high prevalence of calcified pleural plaques was the striking finding that led us to discover the asbestos exposure of Metsovites 20 years ago.-2 CXRs were the only available screening test then, and not all of them were of good quality. Therefore, we could refer with certainty only to calcified plaques, and not to simple pleural plaques. As a consequence, the presence of PCs was used thereafter as the hallmark of asbestos exposure in this population, and this is what we used in the present study in which we compared the prevalence of PCs in Metsovites from 1978 to 1982 with that from 1998 to 2002.
The populations of the two studies had to be different. It is practically impossible to repeat now a general population study. The inhabitants of Metsovo think that their problem is solved since we have already proven the causative role of luto in their increased prevalence of PCs and mesothelioma. Now, Metsovites react to any type of publicity, because it gives a negative picture and can harm the tourism to the village, even though we reported long ago that there was no more asbestos exposure in Metsovo. This reaction remains a serious obstacle for new epidemiologic research in the area involving the general population. Therefore, we used the only available alternative, the evaluation of CXRs from the records of the Metsovo Health Center and the two Hospitals in Ioannina.