Temporal patterns of exposure and nonmalignant pulmonary abnormality in Quebec chrysotile workers

Questionnaire, radiographic, and lung function information for 983 Quebec chrysotile workers at work in 1966 was used to develop five clinical response scales (i.e., parenchymal and pleural fibrosis, airflow limitation, chronic bronchitis, and airway reactivity). The relationship of the scales to variables describing temporal patterns of exposure was studied, taking into account cumulative exposure, age, and smoking. All response scales related to variables containing only time information, and in all cases temporal patterns of exposure influenced exposure response relationships. For pulmonary fibrosis, the strongest relationships were to cumulative exposure; for pleural fibrosis to exposure peaks and residence time of dust in the lung; for airway reactivity to early and recent exposure; and for airflow limitation and chronic bronchitis to smoking and to dust level and load over time. These results add to the gathering evidence that exposures to environments containing airborne asbestos may result in airway abnormalities.