Formaldehyde Exposure at Work Linked to Increased Cancer Risk

A study of more than 25,000 workers at factories that produced formaldehyde and formaldehyde resin found workers with the highest exposures had a 37 percent increased risk of death compared to those with the lowest levels of exposure, the scientists reported in the "Journal of the National Cancer Institute."

The research provides an additional 10 years of follow-up data to an ongoing study of workers employed at plants that used or produced formaldehyde.

"The overall patterns of risk seen in this extended follow-up of industrial workers, while not definitive, are consistent with a causal association between formaldehyde exposure and cancers of the blood and lymphatic system and warrant continued concern," said lead author, Laura Beane Freeman, PhD of the NCI Division of Cancer Epidemiology and Genetics.

"We know that various groups of professionals who may experience high peak exposures to formaldehyde are at increased risk of leukemia, but the evidence from studies of industrial workers, among whom exposure levels and patterns may be more variable, has been conflicting," said Beane Freeman. "The fact that we see an excess in this study of industrial workers, which is both the largest and the one with the most extensive exposure assessment, is notable."

Formaldehyde is widely used for industrial purposes and as a preservative and disinfectant.

The International Agency for Research on Cancer classifies this chemical as a human carcinogen, based on its association with nasopharyngeal cancer in an area at the back of the nose toward the base of skull.

In 1995, the most recent year for which figures are available, the U.S. Occupational Safety and Health Administration estimated that 2.1 million workers in the country were exposed to formaldehyde.

At this piano factory in Massachusetts, the workers wear coveralls to protect them from urea formaldehyde glue. (Photo credit unknown)

Since the 1980s, the National Cancer Institute has studied cancer deaths among a group of 25,619 workers, predominately white males, who were employed before 1966 in 10 industrial plants that produced formaldehyde and formaldehyde resin and that used the chemical to produce molded-plastic products, decorative laminates, photographic film, or plywood.

In the report published Tuesday, which includes an average follow-up of over 40 years, researchers found a statistically significant association between death from all blood and lymphatic cancers combined and peak formaldehyde exposure.

Workers with the highest peak exposures had a 37 percent increased risk of death compared to those with the lowest level of peak exposures.

This represents an excess risk of death from several specific cancers, including Hodgkin's lymphoma, multiple myeloma, and myeloid leukemia — the type most often associated with chemical exposure.

In this study, the risk of death from myeloid leukemia was 78 percent higher among industrial workers with the highest peak exposures compared to those with the lowest peak exposures.

Excess risks of death from myeloid leukemia have also been reported among pathologists, embalmers, and other professionals who experience high-intensity peak exposures to formaldehyde.

The highest level of increased risk of death from myeloid leukemia in this study occurred early on and has been declining steadily over time.

In a previous report from this study, which included data on cancer deaths through 1994, researchers showed that the risk of death from leukemias, myeloid leukemia in particular, increased with higher levels of formaldehyde exposure.

Scientists have not been able to identify a mechanism for how normal white blood cells might become leukemic following exposure to formaldehyde, because there is no direct evidence that formaldehyde damages cells in the bone marrow.

Beane Freeman called for further studies to evaluate risks of these cancers in other formaldehyde-exposed populations and to assess possible biological mechanisms.

The Formaldehyde Council, an industry group, took issue with the report, saying the scientific data on which the report is based does not support the inferences put forth by the authors, who admit that their study proved no definitive link to cancers of the blood and bone marrow.

"Despite acknowledging that their findings are not definitive, the authors of the study took the step of asserting a possible link, rather than practice some prudent epidemiological restraint," said Betsy Natz, executive director of the Formaldehyde Council.

The Formaldehyde Council is calling for a full scientific review of the health effects of formaldehyde by the National Academy of Sciences and the U.S. EPA.

"Although the Environmental Protection Agency has yet to act upon a 2008 Congressional recommendation for the NAS review," Natz said, "we are hopeful that it will do so soon."

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