A new study suggests that pesticides and other environmental pollutants may advance the progression of amyotrophic lateral sclerosis (ALS), or Lou Gehrig’s disease. ALS is a rapidly progressive neurodegenerative disease that causes people to lose their ability to move their limbs and body.
The new findings, published in the Journal of Neurology, support previous research revealing increased levels of numerous pesticides in blood tests of people with ALS.
“Our latest publication shows that other toxins like polychlorinated biphenyls, known as PCBs, are also elevated in ALS patients and correlate with poor survival,” said senior author Eva Feldman, M.D., Ph.D., neurologist and director of the University of Michigan (U-M) ALS Center of Excellence.
“Our research shows that environmental pollution is a public health risk that we believe must be addressed.”
For the study, 167 U-M patients had blood drawn shortly after being diagnosed with ALS. They were then divided into one of 4 groups based on the concentration of pollutants in their bloodstream.
The group with the highest amount of pollutants had a median survival time of 1 year and 11 months from the initial date of ALS diagnosis. Meanwhile, the group with the lowest concentration of pollutants had a months-longer median survival time at 2 years, 6 months.
“Our concern is that not only are these factors influencing a person’s likelihood to get ALS, but also speeding up disease once they have it,” said Michigan Medicine neurologist Stephen Goutman, M.D., M.S., the study’s primary author and the director of U-M’s ALS clinic.
Michigan has one of the highest rates of ALS in the country, according to the Centers for Disease Control and Prevention. Thus, Michigan Medicine researchers are uniquely positioned to investigate the origins of ALS in the search for more effective treatments and, eventually, a cure.
“‘Why us? Why Michigan?’ We believe the answer may lie in the fact that Michigan is both an industrial and agricultural state,” said Feldman, who founded Michigan Medicine’s ALS Center of Excellence in 1998.
Throughout Michigan’s farming history, a variety of persistent environmental chemicals have been used in pesticides. These chemicals are absorbed into the ground and can potentially reach water supplies.
While harmful pesticides have been identified and banned, such as DDT in 1972, their consequences persist, taking decades to degrade in some cases. These chemicals can accumulate in the sediments of rivers and the Great Lakes, as well as in the fish that live in these waters.
In addition, Michigan’s industrial activities have placed the state among the top five generators of hazardous waste in the U.S., with 69 designated Superfund sites.
PCBs, which are non-flammable, human-made chemicals used in electrical and hydraulic equipment, were in use until 1979. Similar to pesticides, these industrial chemicals degrade slowly, can leach into the ground and may impact the environment for decades to come.
“If these chemicals are getting into the water bodies, such as lakes and rivers, in Michigan, this could be a source of exposure for everybody,” Goutman said.
“These persistent environmental chemicals take a long time to break down, sometimes decades. Once you’re exposed they may accumulate in your body.They get into the fat and can be released into the blood. We’re particularly concerned about ALS patients who have been exposed to higher amounts of these chemicals,” he said.
“As pollution changes the environment, we are being exposed to more and more toxins. We don’t yet know how this is going to contribute to human disease over time. As we look at more toxins, we want to identify those that are of greater significance in terms of disease onset or progression,” Goutman said.
“If we can determine what these chemicals are doing to our organs, brains and motor neurons, then we can develop drugs to counteract those effects.”
Next, the researchers plan to evaluate a new group of patients in U-M’s clinic. Repeating similar results would further validate their findings, they say, establishing the framework for a national study.
The team has also received funding from the U.S. Centers for Disease Control and Prevention to understand the metabolism and interactions of pesticides and pollutants in ALS patients, and how specific metabolites correlate with disease onset, progression and survival. Feldman said understanding the metabolism of pesticides will lead to drug discovery.
Source: Michigan Medicine