The comment about "a typical latent period" is misleading and my response was previously stated in the reply to Ohlson [ 19891. Essentially, the latent periods for the various studies are a reflection of the definition time of the cohorts and the period of follow-up. The Mancuso study by the very nature of its design had a much longer period of follow-up and clearly shows that chrysotile can have a much longer latent period than previously suggested, simply because no one had followed a similar cohort for that length of time. In the cohort study, the number of mesotheliomas exceeded the lung cancers, and there was no increase in lung cancers in the succeeding decades of observation.
In reference to the second comment, the Mancuso [1988] paper provided, by year for 1920-1930, the official documentation of the amount imported of crocidolite and amosite combined, which constituted an extremely small fraction compared to chrysotile for the entire United States, continuing into the next decade. The McDonald statement that "for the decade 1930-1940, the United States was in fact importing annually about the same amount of crocidolite as England" is not relevant at all, considering the comparative geographical and industrial size of England and the United States with millions of places of employment, industries, and places of use of asbestos. Further, the purposes and amounts of different types of asbestos of what was used in England in that time period cannot be assumed to have occurred in the United States and did not occur relative to the railroad industry, with England using primarily amphiboles as the more readily available form of asbestos. In contrast, in the United States chrysotile was the most readily available type of asbestos coming from Canada. English companies owned the South African crocidolite mines; U.S. companies largely owned the Canadian mines. Further, as stated in the text (page 640), the largest manufacturer of asbestos products in the United States never used crocidolite for insulation at any time 1928-1968. " In reference to the comment about "other evidence," it would be helpful if McDonald would publish for each of his cohort studies, the same data as provided by the Mancuso study; by year of hire, sex, race, number hired that year, age at hire, age at death, year of death, for all cases of mesotheliomas, as well as lung cancer and other forms of cancer, together with the number dead, and those not found or traced.
Regarding one suggestion of analysis of tissue, Mancuso cited on page 650, the experimental evidence expressed by LeBouffant [ 19801 and Sebastien et al. [1979, 19801, they showed that analysis of lung tissue is very misleading when considering