The Journal recently published an epidemiological study by Hauptmann et al. (1) that focused on formaldehyde exposure and mortality from lymphohematopoietic cancer among embalmers. It concludes that duration of embalming practice is " . . . associated with statistically significantly increased risk of mortality from myeloid leukemia." The study is based on 6808 embalmers who died from 1960 to 1985 and were included in three earlier proportional mortality ratio studies (2-4). No proportional

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... ality ratios are presented in the new study, and so we calculated several. Comparison was with deaths among white men who were aged 25 years or older in the United States in 1979, the likely median year of deaths among the embalmers. For all lymphohematopoietic cancers, the proportional mortality ratio was 90 (95% confidence interval [CI] = 76 to 106) and, for the myeloid leukemias, it was 108 (95% CI = 70 to 156), which was based on 29 deaths. The proportional mortality ratio of 128 (95% CI = 35 to 328) for nasopharyngeal cancer was based on four deaths among the embalmers. Proportional mortality ratio studies have limitations and may be misleading. However, we suggest that their principal limitation (self-selection into the study group) is minimal in the embalmers study because of the geographic range (virtually nationwide) and time span of their starting employment (50 or more years). Interviews with coworkers and next of kin of the decedent embalmers were conducted in 1990-1992. These interviews related to occupational exposures that occurred from the 1920s through 1985. Participation rates are not provided for these interviews. Six indices of formaldehyde exposure were derived for each subject from the interviews and from the Notes