a study on the applicability

Editor,-We are sorry to see that Morgan, in his Forum article in 1993,' has repeated criticisms of our study that are totally without foundation and have already been effectively countered. In our reply to earlier remarks along the same lines made by Lapp and Morgan2 on our paper,) we stated that the inclusion of anthracite workers made no difference to the results, the findings being essentially the same when they were removed from the study group. Our earlier response also noted that the dust exposure effect was evident when various indicators of exposure were used (from a surrogateyears of work underground-to exposure estimates derived from data other than that which he questions). As for the smoking effect we reported what we found. The results differed little when various analytical approaches were used, and are similar to those found by other researchers for cross sectional studies of cohorts of current work-

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