I have this notion of sewage plant workers: they NEVER get sick while working over multi-year/decade periods at the plant. It's all anecdotal, because it was from a quote in an article, and you don't know if the guy was telling the truth, but it stuck with me for some reason. Who makes a claim like that and then connects it to working at a sewage treatment plant? I think originally I read about it in a NY Times article about the sewage treatment plant workers' union a few years back but I currently can't find it.