Hydrofluoric Acid Exposure at Work Stanford Linear Accelerator Center Emergency Response Maria G. Gherman MD MPH 5 th International High-Energy Physics Technical Safety Forum April 13, 2005

Hydrofluoric Acid or HF F Is an aqueous acid that emits a colorless, irritating gas at room temperature F Strong inorganic acid, very corrosive F Used for etching circuit boards, glass, silica wafers and metal F Common in household products: rust removers or chrome polishers

HF Use at SLAC F Bldg 25  What concentration?  What size container? F 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) 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 ml) 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 minutes before ambulance help arrived.

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 surface- acting 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