Mesothelioma in a connecticut friction plant: the need for transparency and exposure information in attribution of risk.

Several investigators, including myself and my colleagues, have addressed the issue of mesothelioma among employees of the Raybestos Manhattan friction products plant in Connecticut (CT) that, according to McDonald et al. (1984), mainly used chrysotile asbestos. Anthophyllite was used starting in 1957, and a small volume of crocidolite was used between 1964 and 1972 (McDonald et al., 1984). Our investigation was a mesothelioma case– control study based on incidence data through 1977 from the CT tumor registry (Teta et al., 1983). We identified three mesothelioma cases, two female clerical workers in the friction plant and one male who worked in a parent asbestos textile plant. McDonald et al. (1984) published a cohort mortality study of male workers at this plant that did not identify any mesothelioma deaths based on death certificates, also through 1977 (McDonald et al., 1984, 1986). The male mesothelioma case identified by Teta et al. (1983) did not meet the inclusion criteria for the McDonald et al. (1984) cohort study, and the two female workers, both of whom were in the cohort, were not certified at death as having malignant mesothelioma (McDonald, 1986; Teta et al., 1986). Almost 20 years later, Egilman and Billings (2005), in a case series report, cite six cases of mesothelioma at this plant based on information from lawsuits. This case series was recently updated by Finkelstein and Meisenkothen (2010). The current case series by Finkelstein and Meisenkothen (2010) reports six workers from the CT plant who died of mesothelioma. The authors attempt to correct the Egilman and Billings (2005) list and combine the results with the two female cases we identified in 1983. Finkelstein and Meisenkothen (2010) removed two of Egilman and Billing’s reported six cases because one worked at the Raybestos Pennsylvania (PA) plant, but not at the CT facility, and one had mixed exposure due to Navy experience. According to a recent deposition of Dr Finkelstein (US District Court, 2010), Mr Meisenkothen, his coauthor and a plaintiff’s attorney for mesothelioma cases, reviewed the work histories available from the plaintiffs’ case files and provided the limited information (in Table 1 of their article) to Dr Finkelstein. This underscores the uncertainties relative to the four cases derived from lawsuits. Based on my knowledge of the CT facility, there are a number of uncertainties about these cases that were not made transparent by Finkelstein and Meisenkothen (2010). The key issue is not whether there are former employees of the CT plant who developed mesothelioma, but whether they are attributable to chrysotile exposure at this facility. Finkelstein and Meisenkothen (2010) make no such distinction nor consider any uncertainties about their six reported cases, relying solely on work histories available from the plaintiffs’ case files and assumptions regarding the two female cases we identified. For example, the following are some of the issues that these authors should have discussed with regard to the two cases included from Teta et al. (1983):