Exposure to Diesel Exhaust May Increase Risk of Amyotrophic Lateral Sclerosis

Individuals who have prolonged exposure to diesel exhaust at work may have a higher risk of developing amyotrophic lateral sclerosis (ALS) compared with the general population, according to the American Academy of Neurology, who will present the findings of the study at its meeting in April.

The preliminary findings also showed that the risk of ALS increases along with greater exposure to diesel exhaust.

“There is some suggestion from previous studies of occupation that workers in jobs with higher exposure to diesel exhaust may have a higher risk of ALS. However, no studies have directly looked at the relation between diesel exhaust exposure during different time points in life and ALS,” study author Aisha Dickerson, PhD, said in a press release. “The overall risk of developing ALS is low, but our findings suggest that the greater the exposure to diesel exhaust, the greater the risk of developing ALS.”

Included in the study were 1639 individuals from the Danish National Patient Registry with an average age of 56 who were diagnosed with ALS between 1982 and 2013. Patients with ALS were then matched with 100 control patients.

The authors gathered employment history for each patient and calculated exposure to diesel exhaust prior to diagnosis by measuring potential hazards.

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The study also estimated cumulative exposure and exposure up to 5 and 10 years before diagnosis in order to account for time it may take to affect ALS risk, according to the authors. Patients were split into 4 cohorts based on exposure level to diesel exhaust.

The authors discovered that men with any amount of diesel exhaust exposure within the 10 years before baseline were 20% more likely to develop ALS compared with men who were not exposed during that time.

Notably, the link was stronger among men who had a greater than 50% likelihood of being exposed to exhaust because of their profession. These patients were 45% more likely to develop ALS compared with patients with no exposure 5 to 10 years before baseline, according to the study.

Notably, the link between ALS and diesel exhaust was not seen among women. The authors noted that the tasks for men and women in the same career may vary, which could account for the differences.

These findings remained true even after adjusting for potential ALS risk factors, including socioeconomic status and geographic location.

Although these findings shown an association, it does not prove that diesel exhaust causes ALS, the authors noted.

“This type of exposure deserves more attention and study as we work to develop a better understanding of what causes ALS,” Dr Dickerson said. “Importantly, the general population can be exposed to diesel exhaust from traffic pollution. Understanding whether that exposure increases ALS risk is also an important question to pursue.”