Pesticides used on fruit, vegetables and other crops may be linked to a sharply higher risk of motor neurone disease, with new research suggesting exposure could raise the likelihood by as much as 70 per cent.
People whose jobs bring them into regular contact with these chemicals, including farmers and agricultural workers, appear to face a significantly greater risk of developing amyotrophic lateral sclerosis (ALS), the most common form of motor neurone disease.
ALS affects about 5,000 people in Britain and damages the nerve cells responsible for controlling voluntary movement.
As the condition progresses, patients can experience severe muscle weakness, declining mobility, problems with speech and changes in thinking or behaviour, often stripping them of independence and quality of life.
Survival rates remain bleak: only around one in five people with ALS live beyond five years after diagnosis, while many are given a prognosis of just two years.
While the exact cause of the disease is still not fully understood, researchers from the Robert-Sauvé Institute for Research in Quebec say pesticide exposure may be an important factor worth closer scrutiny.
The scientists examined nearly 800 studies, ultimately selecting 11 for detailed analysis, covering data from more than 2,000 people diagnosed with ALS or another form of motor neurone disease.
Their review found that individuals exposed to pesticides in the workplace were about 60 per cent more likely to develop ALS than those with no such occupational exposure.
Farmers and workers exposed to pesticides could be at a 70 per cent higher risk of developing deadly motor neurone disease
But those exposed mostly to herbicides – or weedkiller -had a 70 per cent increased risk.
Pesticides are chemicals used to protect crops by killing or controlling weeds, insects and fungi.
The main types are herbicides, as well as insecticides and fungicides.
Even lower levels of exposure to pesticides of any kind were associated with around double the risk.
Interestingly, when researchers analysed men and women separately, they discovered the worrying link only applied to men.
Commenting on the findings in the journal Occupational and Environmental Medicine, the experts urged officials to introduce ‘interventions aimed at reducing exposure during occupational pesticide use.’
The World Health Organisation has branded pesticides ‘intrinsically toxic’ and deemed them ‘among the leading causes of death by self-poisoning’.
Several pesticides are not permitted for use in the UK.
Insecticide Chlorpyrifos was banned in Britain in 2016 after evidence revealed it can harm the cognitive development of foetuses and young children.
Toxic weedkiller Paraquat was also banned in the UK due to increased risk of Parkinson’s disease.
However, British crops are still sprayed with some pesticides banned by the EU.
These include Dimethomorph, which is typically sprayed on strawberries and onions, Benthiavalicarb, used on potatoes, and Ipconazole, authorised in the UK for barley and wheat seeds.
Experts not involved in the new study have commented on its findings, urging caution.
Dr Johnathan Cooper-Knock, clinical lecturer at the University of Sheffield’s School of Medicine and Population Health, said: ‘The strength of this research is the use of data from eleven different studies and more than 2000 MND patients; the findings are interesting and should lead to further work.
‘However, this is a retrospective analysis which uses indirect measurements of pesticide exposure and it is therefore almost impossible to know whether the effect seen is mediated by the pesticide exposure or some unseen factor which may be correlated with pesticide exposure.’
Dr Nick Cole, head of research at MND Association UK, said: ‘This is a systematic review and meta-analysis, meaning it is a review of selected literature and its statistical analysis.
‘The study cannot establish that pesticides cause MND, only that there is a statistical association in the limited available data… readers should treat the specific percentage increases with caution.’
What is motor neurone disease?
