UCLA Department of Chemistry and Biochemistry
Chemical Safety Office/ EH&S
Safety Notes
Newsletter #4
February 1997
| DANGERS OF
HYDROFLUORIC ACID 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.
HF REACTIVITY
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.
TREATMENT?
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).
Reference:
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
LECTURE BOTTLES
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