Are there any toxins that can cause ALS?

Throughout the history of ALS research, it has long been suspected that certain toxins (“poisons”) might play a role in causing ALS (the toxin hypothesis). Various heavy metals and specific amino acids (BMAA, BOAA) were considered and analyzed as potential toxins. Despite intensive research, no toxin has yet been identified or confirmed as a cause or risk factor for ALS. Nor has any link to ALS been established for various substances currently in use that are known to have toxic potential (e.g., solvents and wood preservatives). Overall, ALS is a neurodegenerative disease for which an external cause involving toxins is unlikely.