Formaldehyde Exposure Linked to Leukemia Risk in Funeral Workers
By Roxanne Nelson
Medscape Medical News
November 30, 2009 — Among people working in the funeral industry, long-term occupational exposure to formaldehyde was associated with a statistically significantly increased risk for mortality from myeloid leukemia, according to a new study published online November 20 in the Journal of the National Cancer Institute.
The authors did not observe any association with other lymphohematopoietic malignancies, and the association with brain cancer was unclear.
According to the report, the number of years of embalming practice and related formaldehyde exposure were associated with statistically significantly increased mortality from myeloid leukemia (P?for trend?= .020) and with increasing peak formaldehyde exposure (P?for trend?= .036).
The greatest risk was among those who practiced embalming for more than 20 years.
Risk Known, Causality Not Established
People working in a number of professions, including anatomists, pathologists, and funeral-industry workers, come in regular contact with formaldehyde, the authors point out. Previous surveys have shown an excess number of deaths attributed to lymphohematopoietic malignancies and brain cancer among individuals working in these professions. However, although the evidence associating occupational exposure to formaldehyde and leukemia is considered strong, it has remained insufficient to establish causality.
This latest study, led by Michael Hauptmann, PhD, a senior statistician at the Netherlands Cancer Institute in Amsterdam, was a case–control study.
The researchers compared all funeral-industry workers in the United States who died between January 1, 1960 and January 1, 1986 from lymphohematopoietic malignancies (n?= 168) or brain tumors (n?= 48) with deceased matched control subjects (n?= 265) who died from other causes.
Information on lifetime work practices and exposure to formaldehyde was obtained by interviews with relatives and coworkers. The authors point out that although close relatives generally do not know details about the workplace, the funeral industry is unusual in that many funeral homes are family owned and operated. Therefore, the next of kin often work and even live with the embalmer.
Increased Exposure Leads to Higher Risk
The authors noted that embalming was most strongly and statistically significantly associated with a risk for myeloid leukemia (odds ratio [OR], 11.2; 95% confidence interval [CI], 1.3 to 95.6; P?= .027). They also observed statistically significant trends with the number of years of embalming (P?= .020) and peak formaldehyde exposure (P?= .036). When the 27 case subjects who embalmed 20 or more years were compared with those who had embalmed for fewer years, there was a statistically significant association between embalming and risk for myeloid leukemia (OR, 4.1; 95% CI, 1.6 to 10.7; P?= .004).
The authors did not find a statistically significant risk between embalming and brain tumors, or any real evidence that the risk increased with the number of years performing embalming. There were 4 deaths among the case subjects from nasopharyngeal cancer, but only 2 of the individuals had performed embalming. However, the average exposure level of those 2 individuals was equal to or higher than the corresponding levels among exposed control subjects for most exposure metrics.
Further Studies Warranted
"Further studies of leukemia risk in relation to specific embalming practices and exposures, as well as similar specific exposure studies in other professional groups that are exposed to formaldehyde and that have an increased risk of leukemia, should help to clarify our understanding of cancer risks related to formaldehyde," they write. "This study adds to the accumulating evidence from studies of industrial workers that increased exposure to formaldehyde is associated with increased risk of myeloid leukemia."
The study was funded by the Intramural Research Program of the National Cancer Institute. The authors have disclosed no relevant financial relationships.
J Natl Cancer Inst. Published online November 20, 2009.
