Hydrofluoric Acid
Exposure at Work
Stanford Linear Accelerator Center Emergency Response
Maria G. Gherman MD MPH
5th International High-Energy Physics Technical Safety Forum
April 13, 2005
Hydrofluoric Acid or HF
 Is an aqueous acid that emits a
colorless, irritating gas at room
temperature
 Strong inorganic acid, very
corrosive
 Used for etching circuit boards,
glass, silica wafers and metal
 Common in household products:
rust removers or chrome polishers
HF Use at SLAC
 Bldg 25
What concentration?
 What size container?

 SSRL
 What
concentration?
 What size container?
Special Hazards of HF
• HF causes an unique chemical burn
• 1) F ions bind to calcium and
magnesium causing failure of various
organs
• 2) H ions cause a deep corrosive
chemical burn that is slow to heal
HF Skin Exposure
• HF is highly corrosive, penetrates the skin
easily causing deep tissue layer
destructions. Pain may be delayed
because the F ion diffusion may continue
for days if untreated.
• HF<20% erythema,pain delayed up to 24h
• HF20-50%erythema,pain delayed 1-8h
• HF>50% immediate tissue damage and
whitish discoloration of the skin
HF Eye Exposure
• HF can cause severe eye burns with
cornea destruction.
• Blindness may result from severe or
untreated exposure
• Immediate first aid and specialized
medical care is required
HF Vapors Inhalation
• Inhalation of HF can seriously damage the
lungs
• Delayed reactions including Pulmonary
Edema ( flooding of the lungs with body
fluids)
• May not be apparent for hours after the
initial exposure
HF Ingestion
• Severe burns to the mouth, esophagus or
stomach may occur
• Ingestion of small amounts of dilute HF
have resulted in death
OSHA Standards
• Permissible Exposure Limit or PEL ( time
weighted average over 8 hours) is 3 ppm (parts
per million)
• 10-15 ppm will irritate eyes, skin, lungs
• 30ppm immediately dangerous to life and health
• 50 ppm even brief exposure is fatal
• Chronic exposure may result in Fluorosis a
syndrome characterized by bone embrittlement,
anemia, weight loss
Case Study 1994, Australia
 A technician working at a fume hood was
believed to be seated when he knocked
over a small quantity (between 100 230ml) of Hydro Fluoric acid (HF) onto his
lap, splashing both thighs.
 The only personal protective equipment
worn was two pairs of wrist length rubber
gloves and a pair of polyvinyl chloride
sleeve protectors.
Case Study
 The technician sustained burns to 9% of his
body surface area, despite washing his legs with
water from a makeshift plumbing arrangement
that supplied water at 6 liters/min.
 No calcium gluconate gel was applied to the
affected area and contaminated clothing was not
removed during the flushing with water.
 The technician immersed himself in a
chlorinated swimming pool at the rear of the
workplace, where he remained for approximately
Contributing Factors
 Lack of adequate personal protective
equipment
 Lack of adequate emergency procedures
 Did not have emergency shower, a slow
water flow rate may have spread HF rather
than wash off
 Did not remove clothing
 Poor ergonomic design of workspace
Large containers to dispense HF
 Did not apply calcium gluconate
Most common exposure is to hands
due to improper PPE
SAFETY PRECAUTION FOR
HF at SLAC
Use alternative materials when possible
Respiratory protection/ Hood/ Ventilation
PPE
Long sleeve PVC arm protection
Long gloves Triple-Polymer acid resistant
Splash protection /aprons /long pants /closed
toe shoes
Face Shield
Handling Procedures
 Incorporate HF hazards into JHAM
 Use small containers for dispensing
 Ensure appropriate ventilation/ fume hood
 Ensure other people in the area are aware of the hazard
 Keep calcium gluconate available at the work station
Emergency Procedures
Because HF may not burn immediately,
assume any liquid exposure is HF
Take immediate action
Flush with copious amounts of water
Remove contaminated clothing
Apply calcium gluconate gel and massage
it for 15 minutes
Seek additional medical attention
Report all exposures
Calcium Gluconate gel 2%
Topical antidote for HF
skin exposure only
Store between 59-86F
Verify the expiration
date
Use nitrile examination
gloves to apply it
Zephiran 0.13% solution
• Cationic quaternary ammonium surfaceacting agent
• Is an effective treatment for short-term
dermal exposure to HF
• Is used by soaking towels and using them
as compresses for the HF burned area
until pain is relieved
SLAC Emergency Response for
HF Skin Exposure
• IMMEDIATELY rinse the exposed skin with copious
quantities of water being careful to wash the acid away
from other parts of the body, and under finger/toe nails
• Removed HF contaminated clothing in the shower and
continue rinsing for a minimum 5 minutes
• While washing have someone call SLAC Medical X2281
and Security X 2551
• Puncture the Calcium gluconate tub using the inverted
tube cap and cover completely the affected skin area
with gel
• Use nitrile gloves and massage the gel into the skin and
reapply it every 15 min until the medical staff arrives
SLAC Emergency Response for
HF Eye Exposure
• Immediately wash eyes with water from
the nearest eyewash station for at least 15
minutes while holding eye lids open
• While washing ask somebody to call SLAC
Medical at X2281 and Security X2251 for
assistance
• Do Not use Zephiran or calcium gluconate
to eyes
SLAC Emergency Response for
HF Inhalation
• Immediately leave the area where the
vapors are present
• Close door to the room
• While washing the affected area ask
somebody to call SLAC Medical X 2281
and Security X2551 for emergency
medical assistance
SLAC Emergency Response for
HF Ingestion
• Immediately drink large amounts of water
or milk to dilute the acid
• Do not induce vomiting
• Ask somebody to call SLAC Medical for
emergency medical assistance
• Mylanta, Maalox Tums may be given with
water or milk