[ansel12]

I’ve been in contact with every kind of contamination you can imagine, with no problem. I was Resident Engineer on a sewage treatment plant upgrade project where I regularly had to enter and examine structures that you probably would not have been willing to get within 1000 feet of.

When you are out and about, occasionally stop at a service plumbing shop and ask the guys if they get colds, or get sick often, they will tell you that they don't.

Exposure to some things seems to help the immune system.

[editor-surveyor]

>> “Exposure to some things seems to help the immune system.” <<

.
Absolutely true; exposure through skin contact or intestinal contact, but not by injection directly to the blood.