Dangers of HF

Today I received an email from my supervisor informing me of an online training session to cover the handling of hydrofluoric acid. Included was a story about a chemist at another company who had apparently been exposed to HF, had simply washed their hand, and concluded that it was no big deal. By the next day the chemist had reported to the hospital, and after 2 more days there had been a good chance of losing the end of his/her finger!

Everything apparently turned out fine, but HF is some really nasty stuff. I used some of it once as an undergraduate, but because my advisor had warned me of the danger, I was very careful. Knowing what I know now, he probably could have given me even sterner warnings. With a pKa around 3, it is one of the stronger weak acids, but it's the F^- that causes most of the damage. Fluoride ion is quite toxic. It can penetrate deeply into the skin, forming CaF₂, which depletes calcium levels in the body. According to one source, skin burns of 25 in² or greater can result in serious systemic toxicity and death. Calcium gluconate or calcium carbonate gels are the first line of defense in case of skin exposure, precipitating CaF₂ before it can work its way into the skin. Fortunately, I do not ever forsee myself using HF again.

This is a reminder that chemistry can be a dangerous business, especially when we start taking things for granted. I've had a few close calls over the years, but I've never been hurt. I wish everyone could be so lucky.