Effect of occupational silica exposure on pulmonary function.
OBJECTIVE
To assess the effect of occupational silica exposure on pulmonary function.


METHODS
Epidemiologic evaluation based on employee interview, plant walk-through, and information abstracted from company medical records, employment records, and industrial hygiene measurements.


METHODS
Drawn from 1,072 current and former hourly wage workers employed before January 1, 1986. Thirty-six individuals with radiographic evidence of parenchymal changes consistent with asbestosis or silicosis were excluded. In addition, eight individuals whose race was listed as other than white or black were excluded.


RESULTS
Analysis of spirometry data (FVC, FEV1, FEV1/FVC) only using the test results that met American Thoracic Society criteria for reproducibility and acceptability shows decreasing percent-predicted FVC and FEV1 and decreasing FEV1/FVC in relationship to increasing silica exposure among smokers. Logistic regression analyses of abnormal FVC and abnormal FEV1 values (where abnormal is defined as < 95% confidence limit for predicted using the Knudson prediction equations) show odds ratios of 1.49 and 1.68, respectively, for occurrence of abnormal result with 40 years of exposure at the Occupational Safety and Health Administration (OSHA)-allowable level of 0.1 mg/m3. Longitudinal analyses of FVC and FEV1 measurements show a 1.6 mL/yr and 1.1 mL/yr, respectively, decline per milligram/cubic meter mean silica exposure (p = 0.011 and p = 0.001, respectively). All analyses were adjusted for weight, height, age, ethnicity, smoking status, and other silica exposures. Systematic problems leading to measurement error were possible, but would have been nondifferential in effect and not related to silica measurements.


CONCLUSIONS
There is a consistent association between increased pulmonary function abnormalities and estimated measures of cumulative silica exposure within the current allowable OSHA regulatory level. Despite concerns about the quality control of the pulmonary function measurements use in these analyses, our results support the need to lower allowable air levels of silica and increase efforts to encourage cessation of cigarette smoking among silica-exposed workers.
Hertzberg
Vicki Stover
VS
Department of Biostatistics, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA. vhertzb@sph.emory.edu
Rosenman
Kenneth D
KD
Reilly
Mary Jo
MJ
Rice
Carol H
CH
D000368:Aged; D001336:Automobiles; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008452:Maximum Allowable Concentration; D008875:Middle Aged; D012129:Respiratory Function Tests; D012822:Silicon Dioxide / Q000008:administration & dosage; D012829:Silicosis / Q000209:etiology / Q000503:physiopathology*; D000074606:Smoking Prevention; D013147:Spirometry; D013997:Time Factors; D014481:United States; D014489:United States Occupational Safety and Health Administration
D012822:Silicon Dioxide