Hydrofluoric Acid: Guidance for Laboratories

Hydrofluoric acid (HF) is a solution of hydrogen fluoride dissolved in water that is colorless, highly corrosive, and has a strong, irritating odor. Hydrogen fluoride has many uses within industry including the manufacture of refrigerants, herbicides, high-octane gasoline, etching, and biological staining. Exposure to HF can occur in storage facilities, industrial sites, retail locations, and even as part of a hobby. This document provides pertinent information for users of hydrofluoric acid as exposure can prove fatal.

Health Hazards

• The seriousness of HF poisoning depends on the amount, route, and length of time of exposure, as well as the age and pre-existing medical conditions of the exposed person.
• Exposure to HF can produce harmful health effects and some are not immediately apparent.
• Always take into consideration the concentration of HF that is being used and the type of exposure present.
• The chemical safety data sheet (SDS) for HF can be found online and all users should be familiar with this document.

Exposure Routes

Skin:

• HF is highly corrosive and readily destroys bone and cells within the body by depleting their capacity to function properly.
• Depending on the concentration and duration of exposure, skin contact with HF can cause pain, a rash, and deep, slow-healing burns.
  • Burns do not have to be visible to experience pain at the site of contact.
• Concentrated HF (50 % or greater) destroys skin and tissue upon contact causing severe pain.
  • Even small splashes of a high concentration of HF can be fatal.
• Skin contact with lower concentrations (less than 20%) can have pain and burning beginning hours after exposure.
  • Visible damage may not appear until 12 to 24 hours after the exposure incident.
• Skin damaged by HF may have a long healing process and result in severe scarring.
  • Injuries involving the fingertips may result in persistent pain, bone loss, and nail bed damage.

Ingestion:

• Swallowing a small amount of highly concentrated HF will affect major organs and may be fatal.
  • Extensive damage can be done to the esophagus and stomach as it progresses for several weeks resulting in narrowing of the esophagus.
• Systemic fluoride poisoning can occur.

Inhalation:

• HF gas or vapor can irritate the eyes, nose, and respiratory tract even at low levels.
• Inhalation of HF causes damage to lung tissue, swelling, and the accumulation of fluid in the lungs (pulmonary edema).
  • Damage can be delayed until hours after exposure.
• Breathing in HF at a high level in combination with skin exposure can result in death from an irregular heartbeat and pulmonary edema.
• Exposure limits can be found in the SDS.

Eyes:

• Exposure to the eyes can cause prolonged or permanent damage including visual defects, blindness, or destruction of the eye.
  • This can be caused by HF vapor or a splash into the eyes.

Protection

• Proper personal protective equipment while handling HF includes:
  • Lab Coat and/or a chemical splash apron.
  • Attire that fully covers exposed skin (no shorts, skirts, or open-toed shoes).
  • Neoprene gloves are recommended, but a double layer of nitrile gloves can be used.
  • Chemical goggles along with a face shield are recommended when handling HF. Safety glasses with side shields may not provide adequate protection.
  • When using HF at a concentration greater than 5%, it must always be handled inside of a certified chemical fume hood.
• Lab personnel must be familiar with safety feature location and operation.
  • Eyewash/ Drench hose
  • Safety Shower
  • These safety features will be accessible anywhere that HF is approved for use.
• Do NOT work with HF alone.
• Lab personnel must note that fluorine containing compounds can produce HF upon contact with water. Some examples include:
  • Ammonium Fluoride
  • Sodium Fluoride
  • Sulfur Tetrafluoride
  • Ammonium Bifluoride
• Do NOT eat, drink, or apply cosmetics in the area.
• Anyone working with HF must have knowledge of detailed first aid procedures BEFORE work begins.
  • Areas MUST have calcium gluconate available.
    • Calcium gluconate is an external topical antidote for HF skin exposure that prevents the extraction of calcium from bones and tissues when applied per SDS instructions.
    • Calcium gluconate must always be kept in the refrigerator and replaced among expiration as it has a limited shelf life.
• Wash hands thoroughly.

Emergency Procedures for Exposure

• First aid should be provided immediately based on the HF SDS.
• Seek medical treatment as soon as possible.
• See the references section below for SDS sheets and recommended medical treatment for exposure by the world leading producer of HF, Honeywell.
• Further information can be obtained by contacting:
  • Regional poison control center: 1-800-222-1222
  • Centers for Disease Control and Prevention
    • 1-800-CDC-INFO
    • 1-888-232-6348
    • cdcinfo@cdc.gov

Storage

• Store in a place accessible to authorized users only.
• Containers should remain tightly closed in a cool, well-ventilated space.
• Keep on low, protective shelving that prevents accidental spills or knocking over.
• Never store with ammonia or alkaline materials.
• All HF and HF waste must be in a labeled and chemically compatible container such as polyethylene or teflon.
  • Glass, metal, and ceramic materials are NOT compatible with HF.

Spills

• Follow instructions per the chemical SDS.
• Many spill kits/pads are not adequate for HF spills.
  • Specifically ask a vendor for a kit compatible with HF.
• Evacuate the area and contact UA Environmental Health and Safety for large spills.
• Neutralize small spills with caustics, lime, soda ash, or baking soda.
  • Knowledge of incompatible materials from the SDS is critical.
    • For example, use of silica products ( Floor Dri, cat litter, or sand) can produce the toxic gas silicon tetrafluoride.
    • Exothermic reactions may take place.

References

CDC | Facts About Hydrogen Fluoride (Hydrofluoric Acid)
MSDS Resource Centre (honeywell.com) – 70 %
MSDS Resource Centre (honeywell.com) – 49 %
MSDS Resource Centre (honeywell.com) – Anhydrous