Hazardous Substances UHSP/15/HS/05 Schedule 3.5/06. Enhanced Good Chemical Practice for Work with Hydrogen Fluoride and Hydrofluoric Acid

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Lionel Ross Marshall
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1 Health and Safety Policy Hazardous Substances UHSP/15/HS/05 Schedule 3.5/06 HAZARDOUS SUBSTANCES POLICY - CONTROL MEASURES Enhanced Good Chemical Practice for Work with Hydrogen Fluoride and Hydrofluoric Acid These substances are rapidly absorbed through the skin causing destruction of underlying tissue and are toxic to all cells. Splashes to the skin require prompt treatment, including the use of an antidote in order to prevent serious harm. This document is a schedule from University hazardous Substances Policy. The risks from Hydrogen Fluoride and Hydrofluoric Acid are exceptional: the measures in this document are therefore additional to or alternative to Good Chemical Practice. Further information on implementing these measures is contained in the section Further Information and Guidance, later in this schedule. The Occupational Health staff in the University Health and Safety Unit (tel ) can advise about obtaining the calcium gluconate gel for the emergency pack. A file containing the doctor to doctor letter for the emergency pack is available for downloading from the Health and Safety Policy Documents Web page: Revised June 2006 UHSP/15/HS/05 Schedule 3.5/06

2 CONTENTS Requirements for work with hydrogen fluoride and hydrofluoric acid 1 Emergency Action 1 Immediate first aid 1 Anhydrous hydrogen fluoride release 2 Hydrofluoric acid spillage 2 Emergency equipment 2 Further information and guidance 3 Incomparibilities 3 Register 4 PAGE

3 Schedule 3.5 Hazardous Substances Policy - Control Measures Enhanced Good Chemical Practice for Work with Hydrogen Fluoride and Hydrofluoric Acid Hydrogen fluoride and its aqueous solution, hydrofluoric acid, are very toxic, corrosive, colourless fuming liquids with a pungent smell. They are very toxic and may be fatal by inhalation, in contact with skin and if swallowed. They causes severe and painful burns (though, for the dilute acid, the onset of pain may be delayed by several hours). They are rapidly absorbed through the skin causing destruction of underlying tissue and are toxic to all cells. Requirements for Work with Hydrogen Fluoride and Hydrofluoric Acid 1 Hydrogen fluoride and hydrofluoric acid must be kept in a locked, ventilated enclosure and access restricted to authorised persons only. 2 An entry must be made in the register held in the enclosure to record the removal and return of hydrogen fluoride or hydrofluoric acid, and including the amount(s) involved, the date, and the signatures of the "Issuer" and the "User" and confirmation that a COSHH assessment has been done. 3 Work with hydrogen fluoride and hydrofluoric acid must be performed in a high performance fume cupboard. See recommendations for using fume cupboards. 4 The following personal protective equipment must be worn: A laboratory coat and impervious apron, to keep personal clothing free from contamination; Face shield; Protective gloves (known to be impervious to hydrogen fluoride/hydrofluoric acid) to prevent skin contact when handling hydrofluoric acid or when articles contaminated with hydrofluoric acid are being handled. Further personal protective equipment, including respirator, may be necessary according to the nature and the degree of risk. 5 Protective clothing which has become contaminated with hydrogen fluoride/hydrofluoric acid must be decontaminated before normal laundering. 6 The hydrogen fluoride/hydrofluoric acid antidote and other appropriate emergency equipment listed below must be to hand wherever hydrogen fluoride or hydrofluoric acid are in use. 7 Hydrogen fluoride/hydrofluoric acid must not be deliberately discharged into a fume cupboard or down a drain. Vapour/fume emissions greater than the Occupational Exposure Limit must be scrubbed out, preferably at source. 8 A copy of this policy must be displayed wherever hydrogen fluoride or hydrofluoric acid are in use. Emergency Action Immediate First Aid Treatment NB Anyone who assists a person who has been exposed to hydrogen fluoride/hydrofluoric acid will need to use the appropriate personal protective equipment for their own protection. Skin contact 1 Drench the affected area with clean running water for at least 5-10 minutes to remove acid. 2 Remove contaminated clothing, which is not stuck to the skin, as soon as practicable after commencement of washing. S3.5-1

4 Schedule Apply calcium gluconate gel on and around the affected area and transfer casualty to hospital together with emergency pack. During transit continuously massage gel into the skin. The affected area may be covered with a dressing soaked in gel and bandaged lightly. Eye Contact 1 Flush the eye with clean running water for at least 20 minutes (can be continued during transit to hospital). NB DO NOT apply calcium gluconate gel to the eyes. 2 Transfer casualty to hospital. Inhalation 1 Remove from exposure into fresh air and transfer to hospital. 2 If necessary, seek help of First Aider to resuscitate casualty and administer oxygen, if available. Ingestion 1 Do not make the casualty vomit. 2 If the casualty is conscious (a) Wash out the mouth with water. (b) Give 0.5 litre of water to drink, followed by: (c) 0.5 litre of milk to drink. 3 Transfer to hospital. Anhydrous Hydrogen Fluoride Release 1 Evacuate the building. 2 Seek assistance from Emergency Services. Hydrofluoric Acid Spillage 1 Wear appropriate personal protective equipment - minimum of face shield, apron, gloves and toxic dust respirator (toxic sodium fluoride will be produced). 2 Scatter an excess (10:1) of solid sodium carbonate (soda ash) over spilt hydrofluoric acid and leave to stand for a few minutes. 3 Scoop up residue and transfer to a lidded container for disposal as hazardous waste. 4 Wash site of spillage with copious amounts of water. Emergency Equipment Showers and eye wash facilities or other suitable means for drenching affected areas with water. Personal Protective Equipment Neoprene or PVC gloves, apron, boots. Where a lightweight glove is required, polyethylene/ethylene vinyl alcohol copolymer composite may be used. Type B-P3 filter respirator. NB The personal protective equipment specified is for small scale spillages of hydrofluoric acid which do not require assistance of the Emergency Services. Hydrofluoric Acid Antidote Calcium gluconate gel. Emergency pack containing calcium gluconate gel and a doctor to doctor letter for hospital casualty officer explaining further medical treatment by subcutaneous infusion of calcium gluconate solution. S3.5-2

5 Spillage Large quantity of soda ash (sodium carbonate). Schedule 3.5 Further Information and Guidance Anhydrous hydrogen fluoride is a low boiling point liquid which fumes on contact with air and reacts violently with water and bases, evolving a considerable amount of heat. Hydrofluoric acid is a colourless fuming liquid with a pungent smell. It is an aqueous solution of hydrogen fluoride and is commercially available in concentrations up to 60%. Like other acids, hydrofluoric acid burns the skin by hydrogen ion generation and corrosion. However, unlike other acids, hydrofluoric acid can readily penetrate the skin and it has a potent diffusing capacity in tissue. Furthermore, fluoride can be released as a free dissociable ion into deeper tissue. Fluoride ions complex with some bivalent cations (primarily calcium, but also magnesium) inducing decalcification and corrosion of bone and other local tissue abnormalities resulting in cellular injury and death with subsequent tissue necrosis. In addition to local toxicity, the fluoride ions can get into the circulation and induce systemic reactions. Inhalation Weak vapour concentrations of a few ppm can produce irritation of the nose, throat, eyes and respiratory tract and at 5ppm can cause burns. High vapour concentrations can cause severe burns to the lips, mouth, throat and lungs. Fluid accumulation in the lungs may occur and can lead to death. Skin Contact Hydrogen fluoride can cause deep and excruciatingly painful skin burns. Burns from strong hydrofluoric acid (50-70%) are felt immediately, weaker solutions (25%) may take a few minutes to be noticed, solutions of 1-20% may not be felt for several hours but still result in severe burns. Serious skin splashes have caused death. Calcium gluconate is used as an antidote to skin contacts. Calcium gluconate acts, in particular, to inactivate fluoride ions and this is the purpose of applying the calcium gluconate gel as the first aid treatment following initial thorough washing with water. However, post burn swelling and tissues damage can tend to make the skin impermeable. Delivery of calcium ions to underlying tissue may be improved by injecting calcium gluconate solution into the underlying tissue. But injections may only be administered by or under the supervision of a medical practitioner. Hence the need to get casualties to hospital as quickly as possible. Eye Contact Hydrogen fluoride vapours can dissolve in the moisture on the surface of the eyes and cause irritation. Splashing into the eyes may cause severe and irreversible damage with possible corneal scarring. Ingestion Severe burning and/or perforation of the digestive system which may lead to death. Incompatibilities Hydrogen fluoride/hydrofluoric acid are incompatible with glass and ceramics, aluminium, natural rubber and silicone rubber and nylon. Anhydrous hydrogen fluoride reacts violently with water. S3.5-3

6 Schedule 3.5 Register The following format should be used for the register. Date Substance COSHH assessment completed Amount removed from cupboard User's Signature Issuer's Signature Amount returned to cupboard Issuer's Signature g:\aww7text\uhsp\hs35hf.doc S3.5-4

Safe Method of Use for Hazardous Substances of Higher Risk 2 Hydrofluoric Acid

Safe Method of Use for Hazardous Substances of Higher Risk 2 Hydrofluoric Acid Purpose: This Safe Method of Use applies to principal investigators (PIs), sector managers, designated laboratory person (DLPs),