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Funeral directors could be more likely to develop ALS

Formaldehyde exposure may be to blame for higher rate of neurodegenerative disease

Louise Prime

Tuesday, 14 July 2015

Formaldehyde in embalming fluid might be to blame for male funeral directors’ raised risk of developing amyotrophic lateral sclerosis (ALS), suggests research among nearly 1.5 million adults in the US. The researchers behind the study*, published today in the Journal of Neurology Neurosurgery & Psychiatry, suggested that women funeral directors’ less common involvement in embalming could explain why they were at no greater than average risk of ALS.

Using data from the US National Longitudinal Mortality Study (NLMS), the researchers looked for correlations between people’s occupational exposure to formaldehyde and their likelihood of developing the neurodegenerative disease ALS (also known as Lou Gehrig’s disease). Participants in the NLMS had, when aged 25 or older, provided information about their current or most recent job. This was then rated in terms of both probability and intensity (frequency and level) of occupational exposure to formaldehyde.

The analysis revealed that men in jobs with a high probability of exposure to formaldehyde were more than three times as likely as those never exposed to the chemical, to die of ALS. Women with a high probability of exposure to formaldehyde were not at increased risk of dying from ALS, but the study authors said this could be because too few women were in this category to be able to calculate risk level.

Men rated as ‘high’ for both probability and intensity of formaldehyde exposure were more than four times as likely as unexposed men to die from ALS, but only two deaths occurred in this group. All 493 men in the category of high probability and exposure were funeral directors, as were almost all of the women in this category; no women in this group died of ALS.

The study authors suggested that the difference in risk between men and women exposed to formaldehyde could be because, in the US, women funeral directors tend to be involved in dealing with the families of the deceased person, whereas men funeral directors are more likely to be directly involved in embalming.

They also pointed out that the association that they found between ALS risk and exposure to formaldehyde might not be causal, as funeral directors are also exposed through their work to other chemicals, and to prions. However, previous research has shown that formaldehyde was linked to processes implicated in ALS, including increased permeability of mitochondria, and free radical production.

They wrote: “Our results should be interpreted cautiously. Jobs involving both high probability and high intensity of formaldehyde are relatively uncommon in the USA, and ALS is also rare; there were only two ALS deaths among men in such jobs. Moreover, we did not find a dose–response association between formaldehyde exposure and ALS.”

* Roberts A, Johnson NJ et al. Job related formaldehyde exposure and ALS mortality in the USA. Journal of Neurology Neurosurgery & Psychiatry 2015;0:1–2. doi:10.1136/jnnp-2015-310750

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