The Background:

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that attacks motor neurons. There are currently no effective treatments, and the disease results in death approximately two to four years after diagnosis.

Approximately 85% of ALS is considered sporadic, meaning there is no single gene mutation underlying the disorder. While the full picture of what causes this form of ALS is incomplete, a combination of genetic and environmental factors are believed to drive disease risk and progression (Goutman 2017).  Researchers know that if they could identify those environmental exposures, they would be able to take a critical step to understand the disease and point to specific exposures that should be avoided to decrease ALS risk disease (Goutman and Feldman 2020).

Previous Research:

The team’s previous research has shown that residential pesticide exposure and concentrations of persistent organic pollutants in the blood are associated with higher risks of developing ALS (Su et al.

2016; Yu et al. 2014). Its studies have also shown that higher concentrations of these persistent organic pollutants in the blood are associated with faster disease progression. (Goutman et al. 2019).

It’s clear that occupational setting is an important exposure factor, and exposures to certain materials have been associated with increased ALS risk (Visser et al. 2019; Malek et al. 2014; Dickerson et al. 2019). These findings have aided researchers in identifying certain occupational sectors with increased ALS risk, including the manufacturing, mechanical, military, painting, precision metal, and construction industries (Andrew et al. 2020, 2017; Fang et al. 2009).  The next step is to identify which occupations are at higher ALS risk, along with the job- and task-specific exposures that increase this risk.

The Team from the NeuroNetwork for Emerging Therapies:

• Eva Feldman, MD, PhD, Director, ALS Center of Excellence
• Stephen Goutman, MD, Director of the Pranger ALS
• Stuart Batterman, PhD, Professor of Environmental Sciences and Global Public Health, School of Public Health
• Bhramar Mukherjee, PhD, Chair of Biostatistics and Professor of Epidemiology and Global Health, School of Public Health
• Jonathan Boss, doctoral student, School of Public Health
• Christopher Godwin, lab technician, School of Public Health.

This Study:

The research team sought to “identify occupational exposures that are associated with a higher risk of ALS using both survey and standard occupational classification (SOC) coding procedures.”

ALS participants and neurologically healthy controls recruited in Michigan completed a detailed exposure assessment based on their four most recent and longest-held occupations. Exposure scores were generated from this survey, and occupations were assigned to SOC codes by experienced exposure scientists.

The study reported that ALS participants experienced higher occupational exposure to particulate matter, volatile organic compounds metals, and combustion and diesel exhaust pollutants prior to their ALS diagnosis when adjusted for sex, age, and military service as compared to control subjects. Work in “production occupations” was also associated with a higher ALS risk.

“Understanding these non-genetic ALS risk factors is critically important to identify factors that increase disease risk, underlying mechanisms, and potential preventative strategies,” explained Dr. Goutman. “Our goal is to one day make ALS a preventable disease.”