Indirect validation of a retrospective method of exposure assessment used in a nested case-control study of lung cancer and silica exposure.
Dosemeci-M; McLaughlin-JK; Chen-Q; Hearl-F; McCawley-M; Wu-Z; Chen-G; Peng-L; Chen-L; Rexing-SH; Blot-WJ
Occup Environ Med 1994 Feb; 51(2):136-138
A retrospective method of exposure assessment used in a nested case control study of lung cancer and silica (7631869) exposure was validated using an indirect method. Twenty nine mines and factories from five provinces in China were included. A cohort of 68,285 workers employed during January 1972 through December 1974 at eight pottery factories, one clay mine, ten tungsten mines, six copper/iron mines, and four tin mines was analyzed. There were 316 cases of lung cancer. A retrospective method for assessment of exposure to silica was used. Indices of cumulative total dust (CTD) and cumulative respirable dust (CRD) were calculated by merging work histories of subjects with their historical exposure profiles. Trends in the exposure response relationship between the CTD and CRD indices and exposure to silica and risk of silicosis were evaluated using 376 patients with silicosis and 1,262 controls. Odds ratios (ORs) adjusted for age showed striking trends with both indices of exposure to silica. In the case of CRD, the OR (95% confidence interval) rose from 7.6 for low exposure to 20.0 for median exposure and 51.7 for high exposure. The authors conclude that in view of the strength of the association between exposure to silica and the risk of silicosis, the retrospective method of exposure assessment used in the case control study of lung cancer would be an accurate reflection of whether an exposure response relationship exists between silica and lung cancer.
NIOSH-Author; Cancer-rates; Dust-inhalation; Lung-cancer; Epidemiology; Occupational-exposure; Occupational-hazards; Silica-dusts; Exposure-levels; Statistical-analysis
Occupational and Environmental Medicine