Abstract
Abstract Chest roentgenograms and pulmonary function studies were completed on 83 silicotic sandblasters; 61 returned for longitudinal study, with follow-up ranging from 1 to 7 yr. Estimates of respirable free silica concentrations were based on extensive measurements of airborne dust and protective equipment used. Sixty-three percent exhibited X-ray evidence of disease progression between initial and latest films. Probability of progression increased as duration and level of past silica dust exposure increased and was higher among blacks than whites. Those with large opacities and/or certain symbols (ILO U/C classification) on initial X-ray had a higher probability of progression than those with only small opacities. Declines in pulmonary function were associated with average concentration of silica dust exposure. Those in the lowest category (≤ 1.25 mg m-3) experienced normal mean annual rates of decline (29 ml for FEV1 although 50% (5/10) had exhibited X-ray progression over the same period. Mean annual decline in FEV for the middle and upper (> 3.0 mg m-3) concentration categories were 87 and 166 ml, respectively; 59 and 100% of these categories, respectively, exhibited X-ray progression. Antibody prevalences and immunoglobulin levels were high but unrelated to disease state, X-ray progression or pulmonary function decline.
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