Once upon a time I did an electrical engineering internship on-site at an oil refinery.  Part of my training was to learn about chemicals like HF and how dangerous they were to human life and what to do if exposed.<p>Then I learned about how basically in large oil refineries pipes are leaking all the time and crews are always coming in to fix the leaks in the pipes (but not often repair). I left that industry pretty quick and never looked back.