Dust Exposure Indices at the Earliest Appearance of Pneumoconiosis.
Moore-E; Martin-JR; Edwards-AC; Anderson-HA; MacLaughlin-EA
NIOSH 1990 Sep:672-677
A study was made of indices for dust exposure in workers with newly diagnosed pneumoconiosis, and the power of such indices to predict pneumoconiosis was evaluated. Thirty six workers at an iron (7439896) ore mine, aged 24 to 61 years, were evaluated in two groups. One group had been diagnosed for the first time between 1972 and 1979; the other group had been diagnosed for the first time in 1981. Both were International Labour Office (ILO) category-I or higher at the time of study, but only the second group was initially diagnosed by ILO criteria. Five dust exposure indices were obtained for these workers and for 1673 workers without pneumoconiosis. Indices were years of exposure to detectable levels of dust and cumulative and peak respirable dust and quartz (14808607). Predicted values for pneumoconiosis were determined by multivariate logistic regression analysis. For cases, mean time of exposure at the present company was 147 months, range 61 to 224 months. The only exposure index variable giving a p-value of 5% or less for observed versus predicted values was peak quartz exposure. Relaxing the criterion to 6% added variables of cumulative quartz and years of exposure to the response function. For cases and healthy workers, respectively, peak quartz indices were 912.0 and 34.2(mg/m3)3 times years. Cumulative quartz was 1.8 and 7.6mg/m3 times years and years of exposure was 5.9 and 11.4 years for healthy workers and cases, respectively. Ratios of cases to total workers for these indices rose with increasing exposure, but the rise with years of exposure was not sustained after 12 years. For 1176 workers with cumulative indices equal to or less than the American Conference of Governmental Industrial Hygienists threshold limit value time weighted average of 4mg/m3 times years, pneumoconiosis was present in 0.5%. The authors conclude that peak quartz exposure is a better predictor for pneumoconiosis than is cumulative exposure.
Humans; Iron-workers; Mine-workers; Dust-exposure; Respiratory-system-disorders; Exposure-levels; Quartz-dust; Lung-disease; Occupational-exposure;
Asthma and Chronic Obstructive Pulmonary Disease; Disease and Injury; Respiratory-system-disorders;
Proceedings of the VIIth International Pneumoconioses Conference