Studies of respiratory morbidity in rubber workers. Part III. Respiratory morbidity in processing workers.

Respiratory questionnaires and pulmonary function tests were administered to sixty-five men exposed to dust in the processing are from three rubber tire manufacturing plants. Similar tests were done on 189 "control" workers. Compared with the controls, the processing workers had a higher prevalence of chronic productive cough. Overall, the processing group showed a decrease in the ratio of FEV to FVC. The processing workers with more than ten years of exposure showed a significant decrease in the ratio of FEV1.0/FVC, the FEV1.0, the residual FEV1.0, and the flow rates at 50% and 25% of the forced vital capacity. None of the pulmonary function effects could be solely explained on the basis of smoking, age, ethnic, or socioeconomic factors: all were related to the length of exposure. Based on these results we conclude that exposure in the processing area produces pulmonary disease.