Environmental exposure to home chemicals tied to increased ALS risk

Findings were determined from survey sent to 367 ALS patients

Lindsey Shapiro, PhD avatar

by Lindsey Shapiro, PhD |

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Storing chemicals such as gasoline, lawn care products, and paints in a garage attached to a home was associated with an increased risk of amyotrophic lateral sclerosis (ALS) in a recent analysis.

Researchers believe the findings add to knowledge about environmental exposures — workplace, recreational, or residential — that contribute to the risk and progression of the neurodegenerative disease. Such exposures are collectively known as the “ALS exposome.”

“With each study, we better understand the types of exposures that increase the risk of developing ALS,” Eva Feldman, MD, PhD, professor and director of the ALS Center of Excellence at the University of Michigan, and a senior author, said in a university news release. “We now need to build on these discoveries to understand how these exposures increase ALS risk.”

The study, “Residential exposure associations with ALS risk, survival, and phenotype: a Michigan-based case-control study,” was published in Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration.

Exposure to certain environmental toxins, especially pesticides and heavy metals, has been strongly linked to an increased risk of developing ALS.

Feldman and her colleagues have shown that people with ALS have higher concentrations of organic pollutants, especially pesticides, in their blood than people without ALS and that such pollutants were associated with worse survival outcomes. Lifetime exposure to these factors might predict a person’s risk of developing the neurodegenerative disease, they’ve shown.

While many elements of the ALS exposome come from the workplace, certain recreational activities like woodworking or gardening, where volatile chemicals may be used, have also recently been linked to ALS.

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Environmental pollutants in blood linked to ALS risk, survival

Link between ALS, home-based exposures

Here, the scientists looked at the possible contributions of home-based exposures, given that gasoline, solvents, cleaners, and paints are routinely found at home, especially in the garage.

They sent a survey to more than 600 people, including 367 ALS patients seen at the university’s clinic and 255 people without ALS from the local community, who served as a control group. The participants were asked about their current and previous home environments.

Among the top residential factors associated with an elevated ALS risk was storing chemicals in a garage attached to the house. These included fuels such as gasoline and kerosene, gasoline-powered equipment, lawn care products, pesticides, paint, solvents, woodworking supplies, and bleach, with each raising the odds of developing ALS by anywhere from 9% to 16% with every five years of additional exposure.

Storing these items was also associated with a risk of ALS when they were kept in a garage detached from the home, although the links were slightly weaker.

Researchers believe this makes sense given the flow of air into living spaces through an entry door and small openings in walls and floors.

Other residential factors linked to ALS risk included having a humidifier in the home, central heating systems that used oil as fuel, and having a pet dog, which might “expose residents to pesticides used to control fleas, ticks and other vectors.” The researchers said a humidifier could be “associated with microbial contamination or biocides.”

None of the identified factors were significantly associated with ALS survival, but having pesticides, lawn care products, and woodworking supplies in the home was close to being significant.

Many of the chemicals in the analysis have toxic components and most have been linked to ALS in other studies, especially as they related to occupational exposures, the researchers said.

“Our findings are very consistent with the literature, but … are highly significant in extending the literature by showing that such exposures in residential settings have a meaningful impact on ALS risk,” wrote the researchers, who said their finding that woodworking supplies are associated with ALS are consistent with a recent study where woodworking as a hobby was associated with the neurodegenerative disease.

Stephen Goutman, MD, of the University of Michigan and the study’s first author, said more research is needed to determine whether it’s the “activities that associate with ALS risk or the exposures to related products.”

The analysis had some limitations, including that the respondents may not accurately recall environmental exposures from prior living spaces and not all types of exposures were covered in the survey. Still, the analysis provides insights into the home-based factors that may contribute to the disease.

“Identifying disease-provoking exposures can inform and motivate interventions to reduce exposure, risk and, ultimately, the ALS burden,” Goutman said. “Exposures in the home setting are an important part of the ALS exposome, as it is one place where behavior modifications could possibly lessen ALS risk.”