A new study published yesterday in the Journal of Neurology, Neurosurgery and Psychiatry (JNNP) highlights the link between increased exposure to formaldehyde and an increased risk of developing MND.
The study in the USA was conducted by Andrea Roberts and colleagues at the Department of Social and Behavioural Sciences at Harvard. They investigated whether a person’s exposure to formaldehyde in their occupation increased their risk of developing motor neurone disease (MND).
Formaldehyde is a colourless chemical that is used as a preservative in mortuaries, medical laboratories and by undertakers. Exposure occurs primarily by inhaling formaldehyde gas or vapour from the air or by absorbing liquids containing formaldehyde through the skin.
The study found that those with a ‘high intensity’ and probability of exposure to formaldehyde had nearly four times higher risk of developing MND compared to people who had no exposure to formaldehyde. All participants that fitted these criteria were funeral directors. The increased risk of developing MND in this occupation group was only found in men, with no link found for women.
What do these results mean?
‘High intensity’ refers to the frequency and level of exposure to formaldehyde as part of the study participant’s occupation and industry type. The probability of exposure reflected how likely they were to come into contact with this chemical as part of their occupation.
The difference in results for men and women are because fewer women work as funeral directors, and so are less likely to come into contact with formaldehyde. This made the sample size too small to detect possible increased risk of MND in this study.
This is the first time formaldehyde has been identified as a possible cause of MND and further studies are needed to confirm the results from this study. Two other studies have found no link between estimated occupational formaldehyde exposure and MND. However, these studies looked at occupations where the intensity of exposure was generally lower than in this study.
MND is an extremely rare disease, and people have up to a 1 in 300 chance of developing MND in their lifetime. In comparison, people have up to a 1 in 2 chance of developing cancer (1). The results from this study showing four-times increased risk equates to approximately a 1 in 75 chance of funeral directors developing MND.
Lifestyle and environmental factors and MND
It is not known exactly how environmental and lifestyle factors could increase or decrease the risk of developing MND. Occupational risk factors have been studied, including the possible links between military service and developing MND/ALS, and a person’s exposure to heavy metals, pesticides and chemicals.
MND is a complex disease which is still not fully understood, but any research that can contribute to the growing knowledge of causes and contributing factors can only help our progress in understanding MND. A study last year into the causes of MND found that up to six different genetic, lifestyle and environmental factors are needed in order to trigger the disease. Therefore many more studies need to be conducted in order to establish the causes of MND.
The researchers of this study into exposure to formaldehyde have stressed that caution should be applied when interpreting these results, not least because jobs involving high levels of formaldehyde exposure are uncommon and MND is a rare disease.
Research paper: Roberts AL, Johnson NJ, Cudkowicz ME et al. J Neurol Neurosurg Pyschiatry. 2015 Published online 14/07/2015 doi: 10.1136/jnnp-2015-310750
1. Cancer Research UK (2015), Trends in the lifetime risk of developing cancer in Great Britain: Comparison of risk for those born in 1930 to 1960, Cancer Research UK.