Document 7OjmrjEapZmKgx07jQDDONqpo

94 - IX-2 RESPIRATORY EXPOSURE AND BRONCHIA!. CARCINOMA rtroretccptetetBCKcsBt.BBtUbciicftrtestcpfcBe ** A relationship between the prevalence of bronchial carcinoma and occupa tional asbestos exposure has been established beyond any doubt: the first ob? scrvatlons already date from the thirties. Wagner ct al <1971) reviewed the literature up to that time. Their findings may be summarized as follows: A clear Relationship with occupational asbestos exposure has been estab lished* workers exposed to improved conditions in the factory had little or no excess risk: there apparently is a dose-response relationship, in short (less than two years) intensive exposure as well as in those with intensive exposure over a longer period an excess risk occurs. - There is evidence that combined exposure to^cjrga: cltc .smoke is more like ly to be associated with lung carcinoma than either alone. - More than the risk of mesotheliomas, the risk of bronchial cancer is more clearly related to the intensity of past exposure and to the risk of ashtstosis. In fact this carcinoma is often regarded as a compjication of occupational aub^stesis. - Bronchial tumours are much less clearly linked to the type of asbestos than mesotheliomas. A few studies deserve to he mentioned: In two cohort studies in the Quebec chrysotile .nines and mills (McDonald 1973) an increased incidence of malignant neoplasms in the two highest dust exposure groups was observed, mainly of of the respiratory tract and to a lesser extent of the g*ct **oi ntout i nal tract; * *.c c.xo*s in respiratory cancer, mainly bronchial carci :.^:r.a, became evident bvtv.-en -CO and *500 oppef- years (mppcf * million particles per cubic feet), --r.6 was vl^arly prerent aiovc this level. Gher.ii ct 1 (1972) did rot observe any excess prevalence of lung cancers in workers Iron a chrysotile mine'>ssBalangero (Italy). Enter!inc et al (1973) calculated a t ime-weig;/rva-asbestos dust exposure at the tine of retirement (65 years) in a cohort study of 13*58 men who com pleted their working lifetime in the ib-stos industry and retirfcd curing the P* T* t 1. mi s I 41 1 i V;b c !y i 1c i V *001 C 787 PRODUCED BY FORD