Characterization of dust exposure for the study of chronic occupational lung disease: a comparison of different exposure assessment strategies.

Various exposure assessment strategies were compared in the study of the relation between dust exposure and 11-year lung function change in 1,172 miners with 36,824 concurrently measured personal dust samples available from the 1969-1981 US National Study of Coal Workers' Pneumoconiosis. A miner's average exposure was assessed by calculating average exposures based on dust samples taken from each individual and by using different job exposure matrices (JEMs) with different underlying exposure categorizations, based on occupational categories, job title, mine, and time, to obtain average exposure estimates. For each grouping procedure, intragroup and intergroup variances and the pooled standard error of the mean were calculated to assess relative efficiency. The results show that considerable variation in slopes of exposure-response relations was found using different exposure assessment strategies. Standard errors of the slopes of the exposure-response relations with exposure on an individual basis compared with JEMs. Exposure assessment on an individual basis was extremely sensitive to the number of exposure measurements per individual. The study demonstrates the advantages and disadvantages of different exposure assessment strategies and shows the need for explicit publication of exposure assessment strategies for epidemiologic studies. Careful assessment of the influence of misclassification error in the exposure assessment on exposure-response modeling is warranted.