Document n9Bjq0jD5JrDG16RRBvK50kgz

14256997033 2002-02-26 19:09:21 (GMT), page 13 12 In 1995, Science published a letter to the editor submitted by McDonald and McDonald which indicated that exposure to tremolite, and not chrysotile was the likely cause of mesothelioma cases present in miners and millers who worked in Thetford Mines, Quebec. {!) This was the first in a series of articles in which the McDonalds and other QAMA-funded researchers set forth the argument that there were central (high tremolite) and peripheral (low tremolite) mines in Thetford. {2-10) In subsequent publications they have presented data informing readers that all but one of the mesothelioma cases occurred in miners who had worked in "central (high tremolite) mines." {2-10) * McDonald and McDonald cited a 1989 article by Sebastien et al. as the source of data indicating a wide disparity in tremolite contamination levels between central and peripheral mines in the town of Thetford Mines. {11) In their letter to Science, the McDonalds summarized the information as follows: "The possibility that this distribution (fewer mesothelioma cases in peripheral mines) might be related to the concentration of fibrous tremolite in the two areas was then tested with data on asbestos fiber concentrations in lung tissue from 83 cohort members from Thetford mines who had died from causes other than mesothelioma and had been examined by electron microscopy in 1988. The number of lungs examined was 58 from area A (Central -- high tremolite mines) and 25 from area B (peripheral -- low tremolite mines); the groups were similar in duration of employment (36 and 37 years) and time from termination to death (8 years in both), but estimated accumulative dust exposure was about 30 % higher in group B. The geometric mean concentrations of fibers equal to or greater than five 12