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Estimation of highest task silica exposures.

Grimsley LF
NIOSH 2001 Jun; :1-36
More than one million workers in the United States are exposed to silica and approximately 100,000 will develop lung diseases. Despite efforts to decrease silica exposure in the workplace, overexposures and deaths from silicosis continue in certain operations and industries. According to the National Institute for Occupational Safety and Health (NIOSH), each year more than 250 workers die from silicosis. The objectives of the study were to investigate ways to estimate silica exposure in unsampled tasks and to evaluate the relationship between highest task silica exposure and the development of silicosis. Data from the North Carolina Dusty Trades, a unique resource for exposure response studies of the effects of silica exposure is the basis for the study. Three methods of imputation were used. The methods included estimating exposures based on the geometric mean exposure at sampled commodity-specific tasks, the median exposure of commodity-specific tasks, and a maximum likelihood estimation statistical model. A case-control study design was used to evaluate the effect that estimated silica exposure from the highest task had on the development of silicosis. The results indicate that the highest task silica exposure is related to the development of silicosis. Exposure estimates including values imputed using the geometric mean resulted in an overall, odds ratio and (95 % CI) of 2.27 (1.49, 3.44), for the median imputation exposure method the overall odds ratio was 2.27 (1.49, 3.44); and overall odds ratio of 2.14 (1.47,3.11) for the statistical model. These odds ratio results were not significantly different from overall odds ratio of 2.22 (1.52, 3.26) that was calculated using zero for missing data in the highest task. These results show that the exposure-response relation based on the highest task exposure metric did not increase when non-zero values were imputed using three methods for tasks never sampled. The results are consistent, however, suggesting that peak exposures may be important in the development of silicosis. Further work is needed to better understand the relation between peak exposure and the development of silicosis.
Silica-dusts; Silicosis; Exposure-assessment; Statistical-analysis; Lung-disease; Lung-disorders; Pulmonary-disorders
L Faye Grimsley, Department of Environmental Health, University of Cincinnati, Cincinnati, Ohio 45267-0056
7631-86-9; 14808-60-7
Publication Date
Document Type
Final Grant Report
Funding Amount
Funding Type
Fiscal Year
NTIS Accession No.
NTIS Price
Identifying No.
NIOSH Division
Priority Area
Disease and Injury; Asthma and Chronic Obstructive Pulmonary Disease
Source Name
National Institute for Occupational Safety and Health
Performing Organization
University of Cincinnati
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division