Back in 1998, I scored a consulting job at a silicon plant outside of Salem, OR. Now I was working as a systems admin and I was expected to be responsible for the computer systems, which were basically located in the normal offices, rather than a dedicated machine room floor.

However, since it was an active silicon manufacturing plant, all employees and contractors were obligated to complete safety training sessions. And I swear now that these safety sessions were designed to weed out the faint-hearted guys who weren't serious about supporting this silicon brand.

The safety sessions were simple lectures, with some handouts and PowerPoints, and some of the chemicals they described were absolutely insidious stuff. They were colorless, odorless, and some could melt or disintegrate bone without noticeably affecting the skin or muscles. They said you would just end up with a limp and useless appendage if you spilled some of this stuff on you. Other stuff was highly toxic and you didn't want to breathe anything. Basically it was a big warning to just stay out of the manufacturing floor, especially if we didn't know what we were doing.

I never went near the manufacturing floor. It was a pretty cool job and I wish I lasted longer there. They couldn't scare me away with a safety session, since my Dad had worked for decades in Environmental Health and Safety. Dad knew all about the nastiest stuff and he was always responding to hazardous laboratory accidents. Dad made us the safest home in our ZIP code.

I think Hydrofluoric acid is probably the substance you're describing which leaches the calcium out of your bones. It will certainly burn you too though. It's a common byproduct from heating fluorinated gases and is sometimes used in its own right for wet etching.

As an aside, I love it when they tell you in the safety WBT what the highly toxic gas smells like.

Oh yeah, cleaning chemical vapor deposition chambers in semiconductor industry, that's another one from Derek Lowe: https://www.science.org/content/blog-post/sand-won-t-save-yo...

Silicon fabs are definitely up there for 'regular use of scary chemicals'.