With spring finally arriving, Canadians may eagerly consider resuming hobbies like gardening and golfing. But researchers are warning of potential health risks associated with these hobbies, especially those that heighten pesticide exposure.
Research published in the Journal of Neurological Sciences earlier this year found that outdoor recreational activities, such as golfing, woodworking and hunting may increase a person’s likelihood of developing amyotrophic lateral sclerosis (ALS), especially among men.
Of all the hobbies examined in the study (such as pottery and swimming), golf was linked with a three-times-greater risk of developing ALS among men.
“We know that occupational risk factors, like working in manufacturing and trade industries, are linked to an increased risk for ALS, and this adds to a growing literature that recreational activities may also represent important and possibly modifiable risk factors for this disease,” said first author Stephen Goutman, a professor of neurology at the University of Michigan and director of the Pranger ALS Clinic.
He stressed that although the research found a link between ALS risk and these outdoor hobbies, it shows “association and not causation.”
“We don’t know what exactly the causative mechanism is or if there is causation. We have to dig deeper and have to explore further,” he told Global News.
What is ALS?
ALS, also known as Lou Gehrig’s disease, is a debilitating condition that gradually immobilizes people as the brain loses its ability to communicate with voluntary muscles. As the muscles deteriorate over time, those affected by ALS experience a gradual loss of mobility, speech, and ability to eat, swallow, and eventually breathe.
Each year, around 1,000 Canadians are diagnosed with ALS, with a similar number dying from the disease, according to ALS Canada. And around 80 per cent of individuals diagnosed with ALS pass away within two to five years of diagnosis.
There is no cure for the disease, but there are current therapies such as riluzole, which has been shown in clinical trials to increase survival by approximately six to 19 months.
And on Tuesday Health Canada approved a review for a new ALS therapy, called tofersen, which targets a rare genetic cause of the disease. The treatment is not yet approved, but a regulatory decision is expected in early 2025.
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The precise cause of ALS remains unknown, yet the study in the Journal of Neurological Sciences highlights a growing acknowledgment that the disease arises from a complex interplay of genetic predisposition and environmental influences.
“There’s already been a strong link with ALS to things like metal exposure with pesticide exposure,” Goutman said. “There’s also some probability of physical activity being related to ALS. These are some of the things that we’ve been perhaps hypothesizing in our data.”
The researchers wanted to explore this topic further, studying the possible link between ALS and people’s hobbies.
To find this information, they surveyed 400 people living with ALS and nearly 300 without the condition between June 30 2010 and February 2020 to assess their hobbies and non-work-related activities.
They discovered that for men, engaging in activities like golf, gardening or yard work, woodworking, and hunting was associated with an increased ALS risk.
When broken down by sex, no recreational activities had significant associations with ALS for females, the study said. None of the hobbies were linked to earlier onset of, or death from, ALS for either sex.
“These activities might pose risks in females but are not reaching statistically significant thresholds due to the small number of females engaging in these hobbies,” the authors said.
Why these specific hobbies?
Hobbies such as golfing and gardening or yardwork, Goutman said, may add risk due to the use of pesticides. Previous studies have also linked occupations in golf course and garden maintenance to a heightened risk of ALS, he said.
The study also linked woodworking as a potential risk factor for the disease “given the use of formaldehyde and organic solvents during the process”. Additionally, it argued that some wood species naturally emit organic chemicals, including very volatile organic compounds and formaldehyde.
Regarding hunting, the study notes that this activity could be a source of lead exposure. Shooting can lead to the aerosolization of metals, including lead, antimony, manganese, and boron, depending on the bullet composition, it said.
Dancing was also associated with an ALS risk, although the study said this link may be worth future investigation. The role of physical activity has been debated as an environmental risk factor in past studies.
“Indeed, some types of recreational dancing can reach moderate to intense levels of physical activity, which is significant given the potential role of strenuous physical activity as an ALS risk factor,” the study said.
What now?
David Taylor, the vice-president of research and strategic partnerships at the ALS Society of Canada, says the most recent research sheds light on environmental factors that could be modified to change the trajectory of ALS.
“Of course, in studies like this, it’s really difficult because the associations are certainly not causation,” Taylor cautioned. “And there are a lot of limitations to these studies, especially in a disease like ALS. I think it highlights that we still have a lot of understanding on how physical activity or other aspects may relate to ALS, and we’re still trying to understand that.”
He added that, as someone who constantly thinks about ALS, he will “definitely still golf,” and emphasized this study is not meant to scare anyone but to deepen our understanding of the disease.
Goutman sees the study as revealing a “fingerprint” of potential exposures occurring through activities such as golf and gardening.
The question now, he said, is whether being an avid golfer or a skilled woodworker increases susceptibility to chemicals or fertilizers.
“It’s not the woodworking itself, it’s not the hunting and shooting itself, but maybe a metal and chemical exposure related to that. This may just be markers for the types of chemicals or toxins that that may be driving a higher risk of ALS.”
He expressed hope for additional research funding to delve deeper into these activities and pinpoint precisely what aspects of these hobbies are associated with ALS.
“A lot of people play golf, a lot of people do gardening,” Goutman said. “And there are certainly health benefits of these activities, whether it be cardiovascular health or whether it be mental health. And so, we have to be cautious that we’re not suggesting behavioural modification before we really understand the cognitive mechanism.”
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