Reply to letter by Nolan and colleagues--re: the carcinogenicity of New York state talc dusts in humans.

Abstract

Thank you for the opportunity to reply to the letter by Nolan et al. [2013]. Their letter is organized by numbered conclusions, and my reply follows their ordering. 1. Reply to Nolan et al. Conclusion #1: Expected mesothelioma incidence among talc miners and millers. Nolan et al. comment that my calculation of the mesothelioma rate ratio among the talc miners and millers is a crude approximation. As I explained in my Commentary, I did not have access to the full cohort demographics (only the summary of medians published by Honda et al. [2002]. I made conservative assumptions to estimate an expected incidence based upon United States mesothelioma incidence rates. In particular, I assumed that there was no mortality in the cohort following the end of the Honda follow-up. This assumption would have overestimated the person-years of observation and led to an underestimate of the rate ratio. I think that my estimate is probably “reasonably” close to the actual expectation, but certainly a full calculation using the dates of birth and death of the members of the cohort would be desirable. It is quite possible that additional cases of mesothelioma, that I did not identify, have occurred in the cohort, and that my analysis underestimated the risk of mesothelioma in the work force. 2a. Reply to Nolan et al. Conclusion #2 on the fibers measured in the lungs of NewYork talcminers andmillers by Hull et al. [2002] Nolan et al. write that “Gamble and Gibbs [2008] considered the report by Hull et al. [2002] (cited by Finkelstein) and noted the fiber dimensions in the lung content analysis were not consistent with the dimensions of fibrous particulates airborne at the NYS tremolitic talc mine, suggesting that any anthophyllite or tremolite fibers in the lungs reported by Hull et al., were due to exposures other than in this NYS mine.” It is correct that Gamble and Gibbs [2008] wrote an industry-funded report on the relation between malignant disease and amphibole cleavage fragments. Gamble and Gibbs did state in that report that the source of the fibers in the lungs of the subjects studied by Hull is unlikely to be NY talc mines because “the average width of the fibers in the lungs of the two cases of mesothelioma was considerably less than the average width of 1.3 mm of anthophyllite and tremolite in the milled talc samples studied by Siegrist and Wylie [1980].” Nolan et al. do not comment in their letter that Gamble and Gibbs were incorrect in making this statement. Siegrist and Wylie, in fact, reported no measurements of anthophyllite at all. In their paper, Gamble and Gibbs also wrote that “Kelse and Thompson [1989] reported that 0% of the fibers in NY talc samples had widths less than 0.25 mm.” Kelse and Thompson were employees of the R.T. Vanderbilt Company which hired the R.J. Lee Group, Inc. to analyze workplace air samples from the Gouverneur, New York mine and mill. Nolan et al. do not tell us in their letter that Kelse and Thompsonwrote that the analysts made “PCMparticle counts at 400 magnification in Walton-Beckett graticule measuring at least 5 mm long with a 3:1 or greater aspect ratio. Beyond that, exact particle widths and lengths were not measured (pg 615).” It is my opinion that any statements about length and width distributions, such as those made by Gamble and Gibbs, are not credible when particle lengths and widths were not measured by the microscopists. Thus, of the two studies replied upon by Nolan et al. to state that the fibers in the lungs of the workers studied by Hull were from other exposures, one study made no measurement of fibers of anthophyllite and the second made Disclosure Statement: The authors report no conflicts of interests. Correspondence to:Murray Finkelstein, PhD,MD,Department of Family and CommunityMedicine,UniversityofToronto,MtSinaiHospitalFamilyandCommunityMedicine,60 Murray Street, 4th Floor,Toronto,Ontario, CanadaM5T 3L9. E-mail: murray.finkelstein@utoronto.ca

DOI: 10.1002/ajim.22208

Cite this paper

@article{Finkelstein2013ReplyTL, title={Reply to letter by Nolan and colleagues--re: the carcinogenicity of New York state talc dusts in humans.}, author={Murray Martin Finkelstein}, journal={American journal of industrial medicine}, year={2013}, volume={56 9}, pages={1119-24} }