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Lymphoma/Leukemia Risk among Morticians
Abstract & Commentary
By William B. Ershler, MD
Synopsis: Among funeral workers, the duration of embalming practice and related formaldehyde exposure were significantly associated with an increased risk for mortality from myeloid leukemia.
Source: Hauptman M, et al. Mortality from lymphohematopoietic malignancies and brain cancer among embalmers exposed to formaldehyde. J Natl Cancer Inst. 2009;101:1696-1708.
It has been long known that formaldehyde is carcinogenic, and surveys among those exposed (e.g., anatomists, pathologists, and morticians) have shown excess numbers of deaths due to lymphoma, leukemia, and other cancers.1-3 In a recent analysis by the International Agency for Research on Cancer, formaldehyde was classified as a human carcinogen (group 1) on the basis of experimental observations in rodents and epidemiological studies of exposed groups.4 However, the available epidemiological evidence for occupational exposure to formaldehyde and leukemia was insufficient to establish causality.
Thus, Hauptmann et al investigated the relation of mortality to work practices and formaldehyde exposure levels among these professionals to address cancer risk in the funeral industry. For this, professionals employed in the funeral industry, who died between January 1, 1960, and January 1, 1986, from lymphohematopoietic malignancies (n = 168) or brain tumors (n = 48), were compared with deceased matched-control subjects (n = 265) in regard to lifetime work practices and exposure to the funeral industry, which were obtained by interviews with next of kin and coworkers, as well as estimated levels of formaldehyde exposure. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by use of logistic regression.
Mortality from myeloid leukemia increased statistically significantly with increasing number of years of embalming (p for trend = .020) and with increasing peak formaldehyde exposure (p for trend = .036). Notably, mortality from myeloid leukemia was elevated among those who performed embalmings for more than 34 years (OR = 3.9, 95% CI = 1.2 to 12.5, p = .024), who performed more than 3,068 embalmings (OR = 3.0, 95% CI = 1.0 to 9.2, p = .057), and for those whose estimated cumulative formaldehyde exposure exceeded 9,253 parts per million-hours (OR = 3.1; 95% CI = 1.0 to 9.6, p = .047). Also of note, the exposures did not relate to lymphoma or brain cancer development.
Thus, in a case-control study in a cohort of deceased funeral-industry workers, those who died from lymphoma, lymphoid, or myeloid leukemia or brain cancer were compared with matched controls. The lifetime work practices and exposures to formaldehyde were obtained by interviews with next of kin and coworkers for each case and control. It was found that the duration of embalming practice and related formaldehyde exposures were associated with statistically, significantly increased risk for mortality from myeloid leukemia. No associations were observed for other lymphohematopoietic malignancies, and there were too few cases of brain cancer to ascertain a statistically significant association.
This was a carefully conducted epidemiological study established on the basis of duration and density of exposure to a relationship of formaldehyde with myeloid leukemia. Although the data were derived indirectly (from next of kin and from co-workers), the investigators employed very careful methodology, and derived equivalent information, from well-matched controls. Indeed, this technique of examining only one job type (embalming) and determining individual exposure levels by assessing subject-specific information provides a significant step forward when compared to prior studies in which associations rely on aggregated information for subjects exposed under a variety of different circumstances. For example, when compared to the broader cohort of subjects exposed to formaldehyde,5 funeral-home workers who embalm had a longer duration and higher cumulative level of exposure but lower average intensity of exposure.
The authors pointed out that the survey was based upon embalming practices through the early 1980s and, thus, may not be representative of current patterns of work, particularly with reference to formaldehyde exposure.
1. Harrington JM, Shannon HS. Mortality study of pathologists and medical laboratory technicians. Br Med J. 1975;4:329-332.
2. Blair A, et al. Epidemiologic evidence on the relationship between formaldehyde exposure and cancer. Scand J Work Environ Health. 1990;16:381-393.
3. Stroup NE, Blair A, Erikson GE. Brain cancer and other causes of death in anatomists. J Natl Cancer Inst. 1986;77:1217-1224.
4. Cogliano V, et al. Advice on formaldehyde and glycol ethers. Lancet Oncol. 2004;5:528.
5. Beane Freeman LE, et al. Mortality from lymphohematopoietic malignancies among workers in formaldehyde industries: The National Cancer Institute Cohort. J Natl Cancer Inst. 2009;101:751-761.