UNSW Occupational Health and Safety Unit With special thanks to:

1. UNSW Occupational Health and Safety Unit With special thanks to: Working Safely With Hydrofluoric Acid (HF)

2. Course Outline • Properties of HF • Hazards Associated with HF • PPE required for HF use • Handling and Storage • Waste disposal • Emergency procedures • Spills • Incidents • First Aid

3. Properties of HF What is Hydrofluoric Acid? • Colorless liquid with strong irritating odor • Pungent odor at <1parts per million (ppm) - warning property • Irritation to nose and throat at 3ppm • Peak limit no more 3ppm for 15 minutes • Non-flammable, very soluble in water • Vapor density = 0.7 (air = 1)

4. Uses • Mineral Digestion • Surface Activation (Si) • Silica Digestion • Plastics Production • Etching Glass, metals (Ti, Al) • Electronic Circuit Cleaners • Production & Purification of Radioactive Materials • May also be found in household rust removers, aluminium cleaners and etching solutions.

5. HF properties - Hazards • Hydrofluoric Acid (HF) is one of the most corrosive of the inorganic acids and requires special safety precautions when using this chemical. • HF acid burns are a unique medical problem. • Dilute solutions will deeply penetrate before dissociating, • causing delayed injury and symptoms. • Burns to the fingers and nail beds may leave the overlying nails intact.

6. HF Properties – Medical hazards • High concentrations on contact produces immediate necrosis and pain • Delayed health effects occur at low concentrations. • Local effects include tissue destruction and necrosis. Burns may involve underlying bone. • Serious Systemic Poisoning from severe burns includes: • Hypocalcemia (low Calcium levels) • Hyperkalemia (High Potassium levels) • Hypomagnesemia (low magnesium levels) • Sudden death. • Deaths have been reported from concentrated acid burns to as little as 2.5% Body Surface Area (BSA). (Palm of hand = 1%) • Amputations have occurred from the exposure of fumes of a 2% solution. (LCLo = 50ppm/30mins inhalation)

7. HF Classification – cut offs and labels • Hydrofluoric Acid (7% and over) • T+, Very Toxic, C, Corrosive • R26/27/28, R35 • Very toxic by inhalation, skin contact or swallowed, causes severe burns • >=1% but less than 7% • T, Toxic, R23/24/25, R34, C, Corrosive • >=0.1% but less than 1% • Xn, Harmful, R20/21/22, R36/37/38 • Harmful by inhalation, skin contact or swallowed, Irritating to eyes, respiratory system, skin. • S(1/2) - 7/9 – 26 - 36/37 - 45

8. Exposure types & routes Direct exposure • Liquid exposure • Gas/Vapour exposure Through: • Skin • Respiratory Tract • Eyes • Ingestion (rare) Most HF exposures occur through inhalation of the gas/vapour or dermal contact

9. SKIN • HF is readily absorbed through the skin (osmosis) and deep tissue penetration occurs. • HF binds to the calcium and magnesium in the body. • Important to note that the surface area of burn is not predictive of end effects. The 2 mechanisms that cause tissue damage are: –corrosive burn from the free hydrogen ions –chemical burn from tissue penetration of the fluoride ions

10. Skin pathophysiology What occurs: • Fluoride ions penetrate and form insoluble salts with calcium and magnesium. • Soluble salts also are formed with other elements but dissociate rapidly. • Fluoride ions from this process release, and further tissue destruction occurs.

11. Skin pathophysiology • The initial extent of the burn depends on the concentration, temperature, duration of contact, and quantity Concentration Time to onset of symptoms 14.5% Immediately 12.0% Up to 1 hour 7% or less Several hours* * It may take several hours before onset of symptoms, resulting in delayed presentation, deeper penetration of the un-dissociated HF, and a higher severity of burn.

12. BURNS Weaker solutions penetrate before dissociating. • Surface symptoms in these cases is minimal and may even be absent. • Three categories (grades) of appearance: • 1. white burn mark &/or erythema and pain • 2. white burn mark &/or erythema and pain, oedema & blistering • 3. as above plus necrosis • Ocular burns present with severe pain. • Inhalation burns may develop acute pulmonary oedema. • Erythema is the superficial reddening of the skin • Oedema is a condition characterised by excess watery fluid collecting in the cavities or tissue

13. HF Facts

14. BURNS • Concentrated solutions cause immediate pain and produce a surface burn similar to other common acids with erythema, blistering and necrosis. • The pain is typically described as deep, burning, or throbbing and is often out of proportion to apparent skin involvement. • HF penetrates fingernails burning the pulp beneath without destroying the nails. Adequate treatment of these cases requires removal of the nails and/or intravenous and/or intra-arterial infusion of Calcium gluconate.

15. EYES • The eyes can be severely damaged from either vapor or liquid contamination • Complications of eye exposure include corneal opacification, corneal sloughing, necrosis of the anterior chamber and keratoconjunctivitis.

16. Inhalation • HF is a volatile liquid with a b.p. of 112 C (40%). • Similar volatility to 30% HCl or acetic acid. • Its volatility makes it a high risk compound for inhalation injury. Severity can range from mild airway irritation to severe burning and dyspnea (air hunger). • With inhalation of HF concentrations > 50% there is a significant risk that they will develop pulmonary oedema/ARDS and pulmonary hemorrhage.

17. Inhalation Acute inhalation exposure symptoms include: • chills • fever • tight chest • coughing • choking • bluish coloured lips and fingernails

18. Ingestion Generally from • Poor lab practices coupled with • inadequate personal hygiene after chemical use. • Ensure hands are washed even if you double glove Prognosis • Varies depending on severity of burn and site of burn. • The prognosis following HF inhalation is poor.

19. Before Use in your Project • Read MSDS – ChemAlert and/or manufacturer. • Perform risk assessment on tasks using HF • Identify Hazards, assess & control Risks • Develop Safe Working Procedures (SWP’s) or familiarise yourself with existing instructions • Understand Laboratory protocols • Only use in applications you are authorised to do • Undergraduate classes MUST never use Hydrofluoric Acid solutions.

20. Personal Protective Equipment (PPE) Always: • Use approved splash goggles • Use full face shields • Long Gloves (double glove) that cover wrist • Use Neoprene, nitrile, latex • Check the breakthrough time for the type of glove • Safety glasses give NO splash protection

21. Safe handling Where possible: • Substitute for less hazardous substance • Use the most dilute HF solution practicable • Experienced staff should prepare the dilutions for learners. • Neutralise waste product immediately (lime in Na2CO3 sol’n) ALWAYS • Work in a chemical fume hood at least 200mm from the edge • Use good housekeeping and laboratory practices. • Have a second person in the lab when you are using HF (Buddy System) in full PPE

22. Safe handling Always • use a bottle carrier when transporting HF (never transport open containers) • check your spill/exposure kit contents and location before you start working • check expiration date of the calcium gluconate BEFORE you start procedure NEVER • use in a squirt bottle

23. Spillage Contain and Absorb • Check yourself for contamination • Use proprietary spill absorbent like Chemizorb which absorbs and neutralises HF OR • Use other non Silicon based absorbent and neutralise with lime (CaO) in sodium carbonate solution • OR slowly add NaHCO2, calcium hydroxide or calcium carbonate solid to neutralise to pH7 • Wear reusable gloves, face shield, apron and boots • Consider the need for evacuation and respirators NEVER • Attempt to clean up large spills (>100mL)

24. Storage Always: • use secondary containment (spill containment) • store away from glass containers and incompatibles (consult dangerous goods guidelines) • ammonia • bases • flammables and combustibles • store in acid resistant cabinet below eye level • Replace cap when not in use • HF molecules will migrate through the bottle and disperse harmlessly – do not store in a plastic bag

25. Safe use Never use Hydrofluoric Acid when working alone or after hours (when?). • The buddy system must be implemented whenever using HF. All those working with or around HF must have HF training before commencing any work. • HF may only be used in an approved laboratory. • Before beginning any procedure involving Hydrofluoric Acid, make sure the access to the spill kit, emergency shower and eyewash is unobstructed. • Have a supply of Calcium Gluconate Gel at home for delayed onset pains from unnoticed exposures

26. EMERGENCY RESPONSE For All Exposures (Incl. possible and combined with other chemicals) • Do not panic • Activate buddy system response immediately: (there should always be a second person in the lab when you are using HF) • Buddy to avoid becoming contaminated • Wash area thoroughly with water for 5 minutes • Apply Calcium gluconate gel without hesitation • Obtain MSDS and phone security service X56666

27. EMERGENCY RESPONSE Procedure for Skin Exposure: • Help individual to eyewash/safety shower: • Do not contaminate yourself; use PPCE • 5 minutes in the safety shower (time it) • Victim should remove all contaminated items to remove trapped HF (i.e. clothing, shoes and jewellery while under the shower and put in plastic bags for decontamination) • Remove goggles last • face water stream and pull over head (front to back)

28. EMERGENCY RESPONSE Procedure for Skin Exposure (cont): • Buddy should bag all contaminated clothing and supplies (USE PPE) • After 5 minutes washing - Victim should self administer calcium gluconate: • Gentle continuous massaging in of the gel. • if the victim is unable to administer, the buddy can assist using the disposable latex or nitrile gloves • NOTE THETIME OF INITIAL APPLICATION • (apply every 15 mins until medical help is present)

29. EMERGENCY RESPONSE Procedure for Eye Exposure: • Help individual to eyewash: • Do not contaminate yourself; use PPCE • 15 minutes in the eyewash OR • 5 mins in the eyewash (time it) • Irrigate eye repeatedly via syringe with sterile 1% solution of calcium gluconate (not gel). • Ice water compress may be applied to the eyes during transport to hospital for pain relief. • Avoid rubbing the eyes. • Apply the 2.5% gel to any exposed parts of the face.

30. EMERGENCY RESPONSE Procedure for Inhalation Exposure: • Help individual to fresh air • Call X56666, request ambulance. • Keep the victim warm, quiet and comfortable. • If breathing stops, perform EAR. • Oxygen should be administered ASAP by a trained individual until medical help arrives. • No other first aid treatment is possible.

31. EMERGENCY RESPONSE General Notes: • The responding person or assisting lab personnel must remain with victim until ambulance arrives. • A copy of the MSDS, the calcium gluconate gel and the emergency procedures must be also taken to the hospital. The doctors will thank you. • It must be stressed to ALL medical professionals (doctors, ambos, nurses) that it is not an “ordinary” acid burn, it is HF and it is potentially Life Threatening. • Look for other burn sites on the victim once treatment has begun.

32. Waste Disposal Procedures Waste Disposal Procedures • Regardless of the concentration of HF, it may not be put down the drain. It may also not be neutralized and put down the drain. • Neutralise all waste – e.g. calcium hydroxide • Collect neutralised waste HF in a clearly labelled, appropriate container with a screw cap. • Glass and metal containers are unsuitable. • Where possible do not mix different acids together. • Complete chemical waste disposal form for removal

33. Confidence using HF • If you are uncomfortable using HF • Arrange for someone to undertake experiment on your behalf • Never use any HF solution on your own • Only use HF solutions during office hours • Ensure all safety equipment is checked and operational before use. • No matter what the actual concentration of HF always: • use safety equipment provided • treat it as though you are using full concentration