An Epidemiologic Study of Asbestos-Related Chest X-ray Changes to Identify Work Areas of High Risk in a Shipyard Population

Abstract

The allocation of resources to protect worker's health were not based on industrial hygiene data mainly due to the unavailability of air level records and the difficulty of retrospective estimation of those levels. A method utilizing chest X-ray findings (as a biological indicator of exposure), smoking history, and job history is presented for the identification of high asbestos risk work areas (shops). The study population included 6183 shipyard workers employed in a West Coast shipyard. The prevalence rate for chest X-ray abnormalities consistent with asbestos exposure (pleural plaques) was 13.2 percent, ranging from 3.9 percent to 23.9 percent in 23 shops. Ratios of age-adjusted prevalence per 100 person-years were computed using the shop having the lowest prevalence for comparison. Workers employed in shops with prevalence ratios greater than 4.0 included the boilermakers, pipefitters, insulators, riggers, and electrician mechanics. Workers in high exposure shops who smoked were found to have the highest prevalence of pleural plaques. The effect of smoking was significant at p < 0.05. Repair and retrofitting of old vessels still constitute potential asbestos exposure through ripout operations. Host factors and prevalence of pleural plaques by work area which serve as surrogates for exposure should be utilized in the planning of prevention strategies.