My husband was diagnosed in 2008, and he was the 5 or 6th person on his job to get it. After his diagnosis, his work conducted a study on the alarm systems used in the government buildings and on the grounds where he worked, and they did not reveal any hazards from that perspective.
Our thought was that he did not show any signs of ALS until he had surgery in 2000. One of the ALS doctors who diagnosed him, said that he is to never have surgery without notifying them first. He said there was a medication given during surgery that they were investigating to cause the start of ALS, something in the anesthesia. I can't remember his exact words, but he went on to say that this medication paralyzes the motor neurons or the surrounding areas of the motor neurons, which could be the catalyst. Something that they are investigating. I haven't heard a follow up regarding this, but it seems like a possibility.