Think about THAT next time you eat lunch after pulling manhole lids.
I figure that one reason I don't get sick very often is due to my frequent exposure to such contaminants.
I know a public works guy who would be working on a broken sewer line, barehanded and he would get him a fresh pinch of chew and never even wipe his hands off on his jeans. I worked on and off with him for several years and was never sick.
Use to do a lot of work for an engineering firm that specialized in retrofits on existing WWTPs. I remember one plant had a lunch room with double doors (that were usually open because of no A/C) with the headworks Parshall flume roaring gloriously not 15' outside the doors. On hot days I've seen the operators sitting on the concrete parapet at the side of the flume eating their lunch. Healthiest bunch of goons I've ever seen.
I couldn't take the smell. When I asked if they ever got use to the smell, someone would always answer, "What smell?"