We have read the letter from Drs. J. Corbett and Alison McDonald [ 19931 with interest. We offer the following points in reply.
In our study " Work-Related Mesothelioma in QuCbec 1967-1990" [Begin et al., 19921, we made no attempt to look at "the true incidence of disease." For that aspect, we specifically referred to the work of McDonald [1980] and the more recent 1989 report of Ruffie et al. We presented cases that were associated with established significant work exposures to asbestos and that had been referred for compensation. Mesotheliomas certainly have occurred in asbestos using industries, and perhaps also in mining and milling, for which compensation was not sought and for which we have no knowledge. 2. The attributability of mesothelioma to chrysotile and/or tremolite is of considerable interest. And the matter is certainly very complex, as the relatively rapid clearance of chrysotile does not necessarily mean that chrysotile is not the initiator and/or the promotor of the process, as is the case for other carcinogens. We hope our work has contributed to the debate, and to the initiation of further investigations into the topic. 3. We all agree that there is an increasing incidence of mesothelioma in Quebec, as in the rest of the world.