UCLA Department of Chemistry and Biochemistry Chemical Safety Office/ EH&S
Newsletter #4 February 1997
TOXICITY OF HF
Anhydrous hydrogen fluoride and hydrofluoric acid are extremely corrosive to all tissues of the body. Skin contact results in painful deep-seated burns that are slow to heal. Burns from dilute (<50%) HF solutions do not usually become apparent until several hours after exposure; more concentrated solutions and anhydrous HF cause immediate painful burns and tissue destruction. HF burns pose unique dangers distinct from other acids such as HCL and H2SO4: undissociated HF readily penetrates the skin, damaging underlying tissue; fluoride ion can then cause destruction of soft tissues and decalcification of the bones. Hydrofluoric acid and HF vapor can cause severe burns to the eyes, which may lead to permanent damage and blindness. At 10 to 15 ppm, HF vapor is irritating to the eyes, skin, and respiratory tract. Exposure to higher concentrations can result in serious damage to the lungs, and fatal pulmonary edema may develop after a delay of several hours. Brief exposure (5 min) to 50 to 250 ppm may be fatal to humans. Ingestion of HF can produce severe injury to the mouth, throat, and gastrointestinal tract and may be fatal.
Hydrofluoric acid is a clear, colorless liquid, miscible with water, with an acrid, irritating odor.
It is an extremely corrosive liquid and vapor that can cause severe injury via skin and eye contact, inhalation, or ingestion.
HF has not been reported to be a human carcinogen. No acceptable animal test reports are available to define the developmental or reproductive toxicity of HF.
The OSHA Permissible Exposure Limit is 3 ppm (as fluoride).
Anhydrous HF has a vapor pressure of 775 mm Hg at 20° C, while Hydrofluoric acid has a vapor pressure of 14 mm Hg at 20° C.
Hydrofluoric acid attacks glass, concrete, and many metals. It also attacks carbonaceous natural material such as woody materials, leather, and rubber. Some materials resist the corrosive action of the acid, such as platinum, wax, polypropylene, polyethylene, and Teflon. In contact with metals with which it will react, hydrogen gas is liberated and the danger exists of a spark or flame resulting in an explosion.
HF is used in many labs and in the glass shop on a regular basis. It should always be stored in plastic bottles. Containers of HF should be stored in secondary containers made of polyethylene in areas separate from incompatible materials. All work with HF should be conducted in a fume hood to prevent exposure by inhalation. Splash goggles and Neoprene gloves as well as laboratory coats should be worn at all times to prevent eye and skin contact.
ACCIDENTS AND FIRST AID
First aid must be started within seconds in the event of contact of any form!
In the event of skin contact, immediately wash with water for 15 minutes and remove contaminated clothing. Any suspected HF contact MUST BE IMMEDIATELY REPORTED TO THE PARAMEDIC PERSONNEL BY DIALING 911. Obtain medical attention at once and inform the physician that the injury involves HF rather than some other acid. In case of eye contact, promptly wash with copious amounts of water for 15 minutes while holding the eyelids apart and seek medical attention at once. If HF is ingested, get medical attention immediately. If HF vapor is inhaled, move to fresh air and seek medical attention at once.
If the injury occurs during normal business hours, a special temporary treatment for HF burns can be obtained by contacting the Chemical Safety Officer, Bill Peck, at 206-3661. The treatment available is a calcium gluconate solution which can be spread over the burn area. It is only meant to be a temporary first aid treatment, but with HF burns, a matter of seconds can be very important, and immediate treatment with calcium gluconate could prevent a more serious burn. A second container will be kept in the Glass Shop, Young Hall, Room 3110.
Spills and Disposal
In the event of a spill of anhydrous HF, call the Hazardous Material Team (Haz Mat) by dialing 55689 or 911.
If a large spill or a spill in a confined area, respiratory protection may be necessary.
In the event of a spill of dilute hydrofluoric acid, neutralize with sodium bicarbonate or lime and soak up the neutralized HF with a spill control pillow or vermiculite. Transfer the material to a polyethylene container or bag and dispose of it. Dispose of it by filling out a Hazardous Waste ID Tag and bringing the waste to the Chemical Safety Office at 2104 Molecular Sciences.(x63661).
National Research Council, Committee on Prudent Practices for Handling, Storage and Disposal in the Laboratory. Prudent Practices in the Laboratory: Handling and Disposal of Chemicals; National Academy Press: Washington D.C., 1995
It has become exceedingly difficult to dispose of lecture bottles that have been stored in laboratories for many months and years. The only manufacturer who will take back lecture bottles is Matheson Gas, and they are currently charging $40 per bottle for this service. They will only accept bottles which are clearly identified as Matheson products, with an intact label, and only if they are still producing the product. Also, there can be no additional fixtures attached to the bottle.
We are not as "lucky" if the lecture bottle is from an unidentified manufacturer and is without a label. The hazardous waste disposal company charges from $100- $1000 to dispose of these unknowns.
It is important to dispose of these lecture bottles as soon as possible after use, while the labels and contents are still identifiable.
It is even a better idea to purchase the smallest size gas cylinder available (rather than the lecture bottle size) so that the manufacturer is responsible for the return of cylinders.
Bill Peck Chemical Safety Officer 2104 Molecular Sciences (20)6-3661, (20)6-5847