Hydrofluoric Acid Exposure at Work

1. 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

2. 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

3. HF Use at SLAC • Bldg 25 • What concentration? • What size container? • SSRL • What concentration? • What size container?

4. 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

5. 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

6. 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

7. 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

8. HF Ingestion • Severe burns to the mouth, esophagus or stomach may occur • Ingestion of small amounts of dilute HF have resulted in death

9. 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

10. 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.

11. 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 35-40 minutes before ambulance help arrived.

12. 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

13. Most common exposure is to hands due to improper PPE

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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

22. SLAC Emergency Response forHF 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