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Engineering | Safe Engineering

I've worked with corrosives before. What makes HF and other fluorides special?

The chemicals below, and related soluble fluoride salts, release fluoride ions (F-):

  • ammonium fluoride (CAS# 12125-01-8)
  • ammonium bifluoride (CAS# 1341-49-7)
  • hydrofluoric acid (CAS# 7664-39-3)
  • potassium bifluoride (CAS# 7789-29-9)
  • sodium bifluoride (CAS# 1333-83-1)

Fluoride ions pass quickly and easily through your skin and other tissues and enter your bloodstream. This means that skin contact can result in skin absorbtion and poisoning.

Fluoride ions aggressively react with free calcium and magnesium — which are important to your health and survival — from your body’s cells. Even small amounts of fluoride poisoning can cause rapid and potentially fatal fluctiations of calcium, potassium, and magnesium in the blood.

Calcium is a necessary part of the cellular contraction and relaxation cycle in muscle cells. Without stable and appropriate amounts of calcium, your muscles — including your heart muscle — cease to function properly. Cardiac dysrythmia is a common complication of fluoride poisoning.

Required Documents

HF Acid or Soluble Fluoride Salt Standard Operating Procedure template (coming soon; in the interim please use the FSE Liquids & Solids SOP Template)

Hydrofluoric acid safety training (for employees)

Hydrofluoric acid safety training (for non-employees)

HF Designated Use Area Sign (contact or to receive laminated signs)

Toxic Soluble Fluoride Salts Chemical Use Area Sign (contact or to receive laminated signs)

Grab-n-Go Hospital Packet template (coming soon)

HF Exposure Flow Chart Sign

Requirements for Safe Usage

Working safely with hydrofluoric acid (HF) or other soluble fluoride salts requires the following:

  • All personnel who have access to the lab space (including the faculty/PI) where the soluble fluoride is used/stored must have completed Hydrofluoric Acid Safety training
  • A written Standard Operating Procedure (SOP)
  • A grab-and-go packet including:
    • a printed copy of your lab’s SOP
    • a printed copy of the Safety Data Sheet (SDS) for the fluoride(s) used in your lab
    • a contact sheet with the following:
      • directions to the nearest hospital
      • contact information for the lab’s faculty (cell phone number)
      • contact information for the lab/school laboratory manager
      • instructions on incident reporting
      • instructions on filling out & submitting worker’s compensation paperwork
  • Calcium gluconate antidote
  • An acid smock or apron with sleeves
  • A face shield
  • Gloves compatible with hydrofluoric acid
  • A spill kit compatible with HF / soluble fluorides
    • this can be assembled or purchased; requires the following:
      • HF-resistant absorbent pads
      • HF-resistant absorbent socks
      • HF-resistant bag/bucket for used cleaning materials
    • neutralizer not required
  • A dedicated fume hood, preferably in an area of the lab with the least foot traffic
  • Signage for “hydrofluoric acid” or “toxic soluble fluoride salts” (depending on what is in use) in the following locations:
    • all doors leading into the room(s) where the soluble fluoride is stored and handled
    • the fume hood where the soluble fluoride is used
    • the chemical storage cabinet(s) where the soluble fluoride and its dilutions are stored

Additional Recommendations for Safe Usage

Another very effective first aid response to HF / soluble fluoride exposure, particularly under the fingernails, is soaking the affected area in a bowl of 1:750 (0.13%) benzalkonium chloride solution with ice. Every 10-15 minutes, or whenever the soaked area becomes painful from excess chilling, remove the affected area from soaking and allow it to warm. If pain from the fluoride burn recurs, resume soaking in the iced benzalkonium chloride solution, until directed otherwise by medical responders.

Note that not all parts of the body can be soaked easily in a bowl, so iced benzalkonium chloride is first aid in addition to — and not a substitute for — calcium gluconate.

Store ice cubes and least 4L or more of the 1:750 benzalkonium chloride (aq) solution in a fridge that is marked “Hydrofluoric (HF) Acid First Aid Only | Not for Storage of Research Materials or Samples.” The same signage should also be placed on the outside of a bowl or tub sized for the amount of benzalkonium chloride being kept on hand. Ice cubes must be food-grade, and not obtained from any lab-use ice machines.