The relation of exposure to asbestos and smoking habit with pulmonary function tests and chest radiograph.

Environmental cum medical study was conducted in asbestos cement factory. The environment was evaluated for asbestos fiber by the methods recommended by BIS. Total 355 exposed and 312 suitably matched control workers were investigated by spirometer, Wright's peak flow meter and full sized postero-anterior chest radiograph. The levels of asbestos fiber were 2 to 3 times higher than TLV i.e. 2 f/ml in pipe cutting dept., crude fiber grinding inlet count was more than the ACGIH recommended limit i.e. 5 mpccf of air in pipe cutting dept. and silica mill. In the rest of the department, fiber level as well as dust particle count were below prescribed limit. The comparison of mean values of PFT parameters of workers with 16-20 years exposure history with control one was showing statistically significant decline in mean values of FVC only suggesting restrictive type of PFT impairment in this group of workers. But in workers with more than 20 years exposure, the mean values of all the parameters studied were reduced as compared to control one suggesting combined type of PFT impairment. When the mean values of PFT parameters of exposed smokers were compared with exposed non-smokers there was statistically no significant difference. This can be due to marginal contribution of smoking habit in impairment of PFT parameters of exposed smokers. The percentages of workers with parenchymal and pleural changes due to asbestos exposure were nearly two times more in more than 20 years exposure groups as compared to 11-20 years exposure groups. The parenchymal and pleural changes due to asbestos exposure were more common in exposed smokers as compared exposed non-smokers. However the detailed analysis revealed that if smoking contributes to the development of interstitial fibrosis, the contribution is a marginal one in comparison to the effect of asbestos dust exposure.

The correlation of chest radiograph and pulmonary function tests in asbestos miners and millers.

An environmental-cum-medical survey was carried out in asbestos mines and milling units at Pullivendalla, Cuddaph (A.P.) India. This was done in two mines and six milling units with 95% of the total work force being surveyed. Out of a total of 633 registered workers, 329 (52%, all males) were employed in mines while 135 (21.4%) workers of whom 114 (84%, all females) were employed in the milling units. All subjects underwent limited medical examination, spirometry and chest radiographs. The levels of asbestos fiber concentration was much below threshold limit value (TLV) in underground mines but several times higher than TLV in milling units. The percentage of workers with abnormal pulmonary function tests (PFT) and chest radiographs increased with duration of exposure in smokers as well as non-smokers. Restrictive pattern of lung functions (159 workers-16.27%) was more common than obstructive (33 workers-5.21%) and combined type (22 workers-3.4%). Similarly, the parenchymal changes (156 workers-24.6%) were more common than pleural (27 workers-4.3%). As most of the males were employed in mines, where the fiber levels were much below TLV, the number of male workers with normal PFT and chest radiographs were ten times (61.3%) more than male workers with both the parameters abnormal (6.3%). As most of the females (114 our of 120--95%) were employed in milling units, where the levels of fibers were several times higher than TLV, the number of females having both the parameters normal 29 (24.1%) or abnormal 35 (29.2%) were similar.

Humoral immunological profile of workers exposed to asbestos in asbestos mines.

Humoral immunological profile including immunoglobulins IgG, IgA, IgM, C-reactive protein, rheumatoid factor, antinuclear antibodies and circulating immune complexes were studied in a representative sample of 36 workers suffering from asbestosis (group A), 35 workers who are exposed to asbestos but not having evidence of asbestosis (group B) and 28 control workers (group C). Mean IgG and IgA levels were found to be significantly higher in the two exposed groups than in the controls. Circulating immune complexes of IgG, IgA and IgM class were detected in a significant percentage of cases in exposed groups than in controls. In groups A and B, the percentage of positive ANF cases was much higher than in the controls. The results suggest that immunological changes are associated with exposure to asbestos and these may play an important role in the pathogenesis of the disease process.