There was a tragic accident in Japan back in 1982: A dentist mistakenly applied HF solution instead of fluorides to a girl, who subsequently suffered extreme pain and died.  Both materials are called フッ素 (fusso, which is actually the name of Fluorine), and there was a fatal miscommunication between dentist&#x27;s assistant and the distributor.   The dentist felt so guilty and stressed out that he died from stroke at the girl&#x27;s funeral.<p>For Japanese in my generation, the fear of HF was imprinted by the accident.  I couldn&#x27;t find English reference, but here&#x27;s Japanese wikipedia page:<p><a href="https:&#x2F;&#x2F;ja.wikipedia.org&#x2F;wiki&#x2F;%E5%85%AB%E7%8E%8B%E5%AD%90%E5%B8%82%E6%AD%AF%E7%A7%91%E5%8C%BB%E5%B8%AB%E3%83%95%E3%83%83%E5%8C%96%E6%B0%B4%E7%B4%A0%E9%85%B8%E8%AA%A4%E5%A1%97%E5%B8%83%E4%BA%8B%E6%95%85" rel="nofollow">https:&#x2F;&#x2F;ja.wikipedia.org&#x2F;wiki&#x2F;%E5%85%AB%E7%8E%8B%E5%AD%90%E5...</a>