Effects of chronic amorphous silica exposure on sequential pulmonary function
Wilson, R.K.; Stevens, P.M.; Lovejoy, H.B.; Bell, Z.G.; Richie, R.C.
Journal of Occupational Medicine. Official Publication of the Industrial Medical Association 21(6): 399-402
1979
ISSN/ISBN: 0096-1736 PMID: 224156 Document Number: 149207
To assess clinical effects of precipitated amorphous silica (PAS), serial spirograms, respiratory questionnaires and chest radiographs of 165 workers exposed for a mean of 8.6 yr were reviewed. Monthly exposure was graded on a 1 to 4 scale and a cumulative exposure index (CEI) calculated for each worker from the sum of measured exposure. A mean exposure index (MEI) was calculated by dividing the CEI by total months exposed. Sputum production and dyspnea were inversely correlated with CEI, while cough and dyspnea correlated with mean pack-years of smoking but not PAS exposure. Linear regression analysis of yearly change of all pulmonary function variables showed no correlation with either the dose of PAS (CEI) or total years of exposure. Among 44 workers with a mean exposure time of 18 yr (range 10-35 yr), yearly decline for FVC were similar to the overall group. Of 143 workers with serial radiographs and exposure to only PAS, none had radiographic pneumoconiosis. Respiratory symptoms in PAS workers could be correlated with smoking but not with PAS exposure, while serial pulmonary function values and chest radiographs were not adversely affected by long-term exposure.