Diachronic study of pleural plaques in rural population with environmental exposure to asbestos.

Background: The progress of pleural plaques in persons exposed to environmental asbestos in Almopia, Greece were studied prospectively.

Methods: During a 15-year period, 198 individuals, in whom pleural plaques had been observed during the period 1988-1990 were followed. Respiratory function was initially evaluated in 23. All were inhabitants of seven villages of Northern Greece, where rocks with high concentration in asbestos fibers were used for whitewashing until 1935.

Results: Out of this population, 126 survived and underwent chest X-ray in 2003 while respiratory function was retested in 18. New radiological findings were compared to previous ones using digital technology. Furthermore, the cause of death of the remaining 72 was recorded. Deterioration of X-ray findings was observed in all survivors. Not only did the surface area of previous plaques increase (8.66 +/- 12.6 cm2, mean value +/- SD) but new ones also appeared. Total lung capacity decreased from 95.6 +/- 14.8 in 1998 to 76.5 +/- 9.3% predicted in 2003. It was found that out of 72 deaths, 11 people died of malignant lung neoplasm, and 4 of mesothelioma.

Conclusions: Radiological appearance of pleural plaques and respiratory function of people previously exposed to asbestos environmental pollution worsens over the years. Prevalence of mesothelioma was found to be higher than expected.