BMAA, Formaldehyde Among Toxins in Environment Linked to ALS Risk
Exposure to certain toxic compounds — including beta-N-methylamino-L-alanine (BMAA), formaldehyde, and heavy metals like manganese, mercury, and zinc — increases the likelihood of developing amyotrophic lateral sclerosis (ALS), according to a review paper.
Its authors argue that with BMAA — a toxic compound made by algae — enough evidence is currently available to conclude that it causes ALS.
The report, “Systematic and state-of the science review of the role of environmental factors in Amyotrophic Lateral Sclerosis (ALS) or Lou Gehrig’s Disease,” was published in Science of The Total Environment.
The causes of ALS remain very poorly understood, with the only firmly established risk factors being age, male sex, or a family history of the disease. A wide body of research has explored whether environmental exposures can influence ALS development.
A trio of scientists at Arizona State University reviewed published scientific literature that explored how the environment may impact ALS. Their review covered 258 studies, most of which used rodent models, that assessed more than 80 different environmental toxins.
“Narrowing possible risk factors to a likely subset will hasten the work needed to determine whether these factors are merely associated or actually causal to ALS,” Melanie Newell, a doctoral student at Arizona State and the paper’s lead author, said in a press release.
The researchers noted that BMAA is the most-studied environmental factor associated with ALS. Based on the amount of data supporting a connection between the two, they asserted that “causal criteria have been met” — in other words, their analysis suggests enough data exist to conclude that BMAA can cause ALS.
Other top-rated risk factors included formaldehyde — a preservative known to be toxic to nerve cells — as well as heavy metals such as manganese, mercury, zinc, and copper.
Further analyses of 62 studies that looked at the statistical relationships between exposure to different toxins and ALS risk generally linked increased exposure to BMAA, formaldehyde, and heavy metals with a higher risk. For example, ALS risk remains high across populations where BMAA contamination through the diet — like eating fish from contaminated waters — is more common.
“BMAA, formaldehyde, manganese, mercury, and zinc emerged as the five highest ranked environmental factors … These are the environmental toxins most recommended for the most immediate research,” the scientists concluded.
“It is important to note that still other environmental factors not yet identified may also play a role in ALS,” they added, stressing a need for further research.
They also used the available data to estimate the prevalence of ALS. In the U.S., there were 16,707 ALS cases in 2015, and this number is projected to increase to 22,654 cases in 2040. If U.S. trends continue, there would be over 200,000 cases by 2240.
“Meanwhile, funding available through the National Institutes of Health (NIH) has been relatively stable for ALS and Parkinson’s disease research, while Alzheimer’s disease research has been increased significantly since 2015,” the researchers wrote.
“Many disease trends in industrialized nations are increasing to an extent and within a rather short time scale which simply cannot be explained by inherently slow genetic changes. To improve U.S. and global health outcomes, studying environment factors is key,” Newell said.