Prevalence of small opacities in chest radiographs of nickel sinter plant workers.

Radiographs from 745 nickel sinter plant workers were taken and classified by five readers using the International Labour Office (1980) protocol. Each reader worked independently and the films were randomly mixed with films from a non-dust exposed office population and also with films from subjects known to have silicosis or asbestosis. The prevalence of small irregular opacities was selected as the outcome of interest. In the sinter workers …