SOURCES: Andrea Roberts, MPH, Ph.D., research associate, Harvard University T.H. Chan School of Public Health, Boston; National Funeral Directors Association; Lucie Bruijn, Ph.D., MBA, chief scientist, ALS Association; July 13, 2015, Journal of Neurology Neurosurgery & Psychiatry
MONDAY, July 13, 2015 (HealthDay News) -- Male funeral directors who routinely work with embalming fluid might be at increased risk of developing amyotrophic lateral sclerosis (ALS), a new study finds.
Those whose jobs involved continual exposure to the formaldehyde in embalming fluid were three times more likely to develop the neurological disease, compared to people never exposed to the chemical, researchers reported in the July 13 issue of the Journal of Neurology Neurosurgery & Psychiatry.
The study found that the jobs of funeral directors involve the sort of frequent and intense formaldehyde exposure that could lead to ALS, often called Lou Gehrig's disease for the famous baseball player who died of it.
"Of the approximately 500 men exposed to very high levels of formaldehyde, they were all funeral directors," said study author Andrea Roberts, a research associate at Harvard University's T.H. Chan School of Public Health, in Boston.
Funeral directors are aware of this potential occupational hazard, and "take these studies very seriously," according to a statement from the National Funeral Directors Association.
The association urges its members to take precautions and minimize their exposure to formaldehyde, mainly by ventilating rooms where embalming occurs as they prepare bodies for burial.
"Adequate preparation room ventilation is the most effective way of reducing formaldehyde exposure," the statement says.
Previous animal studies have linked the chemical to the development of ALS, researchers wrote in background notes.
ALS is a progressive and ultimately fatal neurological disease that attacks the nerve cells responsible for controlling muscles, according to the U.S. National Institutes of Health (NIH). Most people with ALS die from respiratory failure within three to five years of diagnosis, when their diaphragm and chest muscles fail and they lose the ability to breathe.
More than 12,000 people in the United States have ALS, and the condition is thought to affect as many as 450,000 people worldwide. There is no cure, and nine out of 10 times people develop ALS for no apparent reason, according to the NIH.
Researchers decided to explore a possible link between ALS and occupational exposure to formaldehyde, using U.S. Census data gathered on almost 1.5 million adults. When they were 25 or older, participants in this survey were asked about their current or most recent job.
The research team estimated people's on-the-job exposure to formaldehyde using criteria developed by the U.S. National Cancer Institute. They then used death records to track deaths caused by ALS.
They found that men with a high probability of formaldehyde exposure were about three times as likely to die of ALS as those who had never been exposed to the chemical.
That risk increased even more among men who likely were exposed to large quantities of formaldehyde very often.
"We found that, in those jobs in which their likelihood for exposure to formaldehyde was high and the amount of formaldehyde they were exposed to was also high, those people were at four times greater risk of dying of ALS than people with no job related to formaldehyde exposure," Roberts said.
Women with a high probability of exposure did not have an increased risk of ALS. Perhaps too few had jobs that exposed them to high levels of formaldehyde, making it difficult to calculate risk level, the researchers said.
No female funeral directors died of ALS, possibly because they are more often involved in dealing with bereaved relatives than in embalming, which would limit their exposure to formaldehyde, Roberts suggested.
The authors warned that this study does not show a cause-and-effect link between formaldehyde exposure and ALS risk, noting that funeral directors might have a higher risk because of other embalming chemicals or even bacteria or toxins carried on the bodies they prepare.
Lucie Bruijn, chief scientist of the ALS Association, agreed with those reservations.
"The field has seen mixed reports on this, and although the data has been carefully analyzed, further study would need to be done to confirm any association, especially in light of the many other exposures funeral directors are subjected to," Bruijn said. "In addition, jobs involving high intensity of formaldehyde are relatively rare, hence the difficulty in confirming such an association."
For more on ALS, visit the U.S. National Institutes of Health.