Amyotrophic lateral sclerosis (ALS), popularly known as Lou Gehrig’s Disease is a progressive neurodegenerative disease that inhibits control of voluntary muscle movement. Targeting people between the age group of 55 to 75 years, the condition accelerates over time, affecting a patient’s speech, ability to walk, eat and even breathe.

It eventually prevents the brain from controlling the functions of the body which leads to death, most often from respiratory failure.

While the global medical fraternity are yet to find a cure or effective treatment to halt, or reverse the progression of the disease, previous studies discovered links between exposure to certain chemicals found in pesticides and ALS.

A new study supported by the National Institute of Environmental Health Sciences and the National Institutes of Health now suggest another environmental factor which may increase risk of getting the disease — diesel exhaust.

Using information gathered through the Danish National Patient Registry, researchers identified 1,639 people who were diagnosed with ALS between 1982 and 2003. 100 healthy individuals who did not have ALS were then matched with a patient of the same age and sex.

The employment history of both sets of subjects were gathered to calculate their estimated diesel exhaust exposure before being diagnosed with ALS (and the same time period for the healthy participants).

The research team based the estimated exposure on potential hazards for specific jobs like those of construction workers, bus and truck drivers and service station attendants. With this, they were able to determine a collective amount of exposure to diesel fumes that each participant had, five and 10 years prior to being diagnosed.

"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," said study author Aisha Dickerson, PhD, of Harvard T.H. Chan School of Public Health in Boston, Massachusetts. "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."

Based on the data gathered, the study notes that men with any exposure to diesel exhaust at jobs held at least 10 years prior to their date of inclusion in the study were 20% more likely to have ALS than men with no exposure, during the same period.

Men who were 50% more likely to be exposed to exhaust were 45% more likely to get ALS than those with no exhaust exposure at both five and 10 years prior to study inclusion.

Among women, a similar link could not be found but the authors attribute this to the type of work they may have engaged in — the tasks of which may have been different from what the men did.

"This type of exposure deserves more attention and study as we work to develop a better understanding of what causes ALS,” Dickerson said, stressing the study did not prove diesel exhaust causes ALS but only showed an association.

“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," she added. The authors plan to present their findings at the American Academy of Neurology's 70th Annual Meeting in Los Angeles which will take place in April.