Work on STFC sites using any of the following specified chemicals requires additional care and controls:-

1. Working with Lead
2. Working with Beryllium
3. Work with Mercury
4. Work with Hydrofluoric acid (HF)
5. Work with Nano-materials
6. ​​Work with Cadmium and its compounds​
   

​A. Work with lead

See Appendix 5​.

B. Work with beryllium

Beryllium (Be) is used routinely in the STFC, for example as a low scattering vacuum window in X-ray applications.

A concise information leaflet is available from the HSE, "Beryllium and You" (INDG 311).

No fabrication process other than simple shearing of Beryllium metal foil should be attempted on STFC sites.

There is considered to be no significant risk in ordinary skin contact with Beryllium metal and its alloys provided there is no risk of breaking the skin surfaces during the handling operation, hands should be washed immediately after handling. To avoid the possibility of Beryllium contaminating a flesh wound during assembly operations (in some cases such wounds do not heal easily), gloves should be worn. Fine shards and dust caused by the breaking of a Beryllium window should be removed using a vacuum cleaner fitted with a suitable filter, after consultation with the SHE Group.

C. Work with mercury

Introduction

Mercury (Hg) metal and its compounds have a high level of toxicity and are a hazard to health. They can enter the body by absorption through the skin as well as by ingestion or inhalation. The vapour pressure of mercury is such that small amounts exposed to the atmosphere at ambient temperature can produce significant quantities of toxic vapour.

The recommended maximum allowable concentration per cubic metre of air is as follows:-

Precautions

Care must be taken to minimise the exposure of mercury metal to the atmosphere and working situations must be well ventilated. The ambient temperature must be maintained as low as possible to limit vaporisation.

Accumulation of small droplets of mercury in cracks and other inaccessible places is a continuing source of hazard. Such accumulations must be completely removed particularly where any form of heating, vibration, or agitation may occur. As removal is difficult it is important to avoid spills and provision should be made to prevent scattering of any spilt mercury.

Mercury metal and its compounds or contaminated apparatus must not be handled without gloves and protective equipment: strict attention must be paid to washing the hands when work is finished. Persons with any form of broken skin must not come in contact with mercury. Smoking, drinking and eating are prohibited in any situation where mercury is present.

Apparatus containing mercury must be labelled to indicate the quantity involved and instructions in event of a spill. Individual thermometers need not be labelled but it is advisable that pockets for mercury thermometers be labelled as an accumulation could occur from breakages.

Special facilities must be provided where work involving mercury is carried out for long periods and/or where mercury or mercury contamination is exposed to the atmosphere. These special facilities may include rooms with special floors, walls and ventilation; workbenches with special catchment trays filled with water; segregated and marked tools ; clothing and footwear changing rooms ; laundering and washing instructions; permanent monitoring and medical supervision: see SHE Code 24 - Occupational health screening and health surveillance medicals.

Documented operating instructions governing such requirements are strongly advised.

Mercury must be stored in a well ventilated and cool place, sheltered as far as possible from all fire hazards. Containers suitable for the purpose, taking account of the high density of mercury, must be kept closed and clearly marked to be easily recognisable. Attention is drawn to the fact that mercury will attack most metals, and this should be taken into account when selecting container materials.

Apparatus containing mercury or any process using mercury should be reviewed periodically by a responsible officer to see whether safety can be improved. In some cases consideration can be given to substitution by a safer material; for example mercury which for the foregoing reasons should not be used as a heat transfer medium in a bronze thermometer pocket, may be replaced by oil.

Disposal Arrangements

When it is necessary to dispose of surplus or contaminated mercury or mercury contaminated apparatus, clothing or rags etc, advice must be obtained from your Departmental Waste Disposal Officer (WDO), see SHE Code 31 - Disposal of controlled and hazardous waste and the SHE Directory.

Special arrangements exist for the disposal of mercury batteries; these must be packed so that the terminals cannot short circuit and the package labelled "Mercury batteries for disposal" with name and telephone number of the originator must be included. These should be similarly routed through your Departmental Waste Disposal Officer, see the SHE Directory.

Spills​

It is the user's responsibility to ensure that the method and facilities for the decontamination and cleaning up of spills are detailed and available.

In the case of a spillage where local facilities do not exist or is outside the scope of the arrangements, assistance and advice can be obtained from the SHE Group.

Personnel must be withdrawn from the vicinity without delay and the area cordoned off. Maximum ventilation must be given and all forms of heating and hot surfaces should, if possible, be turned off. Persons known to be contaminated or who may be so must be segregated and kept in one location until instructions are received through the SHE Group.

D​​. Work with Hydrogen fluoride (HF)

​Hydrofluoric acid exposures are different from other acid exposures because:

• HF penetrates all tissue it comes in contact with (it does not simply stay on the surface and rapidly penetrates the protective oily barrier of the skin)
• Unlike most other acids, in HF the major toxicity is due to the F- ions, which are able to freely migrate through the body, creating various compounds that can cause systemic effects.
• Unlike other acids, which are easily washed off or neutralised, the effects of HF can last for several days if left untreated.
• Necrosis of deeper tissues is unique to HF because the acid is highly lipophilic and readily penetrates deep into tissue. This is an often delayed reaction and causes a severe ‘pain out of proportion’ to physical examination findings.
  

When users at STFC want to work with Hydrofluoric acid they must first ensure they are thoroughly prepared and that they have completed all of the following:

1. Performed a full written Risk Assessment for the task to be undertaken, including a written COSHH Risk Assessment. The COSHH assessment must address the hierarchy of control and consider substituting HF for a safer alternative.
2. Attended HF Awareness course (1/2 day course), which covers:
   • Nature of Hydrofluoric acid
   • Delayed action on the body of fluoride ions
   • Hypocalcaemia and possible cardiac arrest
   • Recognising HF burns
   • Treatment of HF burns via all routes of exposure:
     1. Skin contact (including a practical demonstration of how to apply the HF antidote, Calcium Gluconate gel)
     2. Eye exposure
     3. Inhalation
     4. Ingestion
     5. Transfer to hospital
3. Have obtained tubes of Calcium Gluconate gel, with sufficient supplies to be able to take one home after experiments (and to inform others at home address how to use in case of delayed onset reaction)
4. Be fully conversant with spill control procedures
5. Have read and followed specific instructions contained with STFC Safety Code SC36, Management and Provision of First Aid (Appendix 9)
6. Have PPE appropriate for the task to be performed – the PPE must be specified in the COSHH assessment
7. Have ensured a second person can accompany users for full duration of HF usage.

In line with the above requirements it is highly recommended that individuals wanting to work with HF ensure the following elements are included in the task work procedure:

1. Review of the documented risk assessment for the task using HF
2. Consider how to minimise the quantity of HF required
3. Consider if it is possible to use a more dilute concentration of HF
4. Ensure ready access to a suitable amount of Calcium Gluconate gel (HF Antidote), with sufficient provision for home use
5. Have printed out copies of risk assessment, safety data sheet and emergency procedures (personal exposures and spills). The emergency procedures could usefully be summarised on a ‘flash card’ which is kept adjacent to the activity.
6. Put up signage to inform other users of the area that HF will be used
7. Make a list of required equipment, ensuring all equipment is ready before starting the activity
8. Put on appropriate PPE for the task, for both the user and accompanying user
9. Perform the task inside a fume hood where ever possible
10. Work on a tray, such that any potential spill can be contained, and ensure a spill kit is at hand
11. Minimise the amount of time during the procedure where exposure to HF can occur
12. Clean area and apparatus up as soon as possible following completion of the task.

Personal Protective Equipment:

Eyes

Use chemical resistant goggles when handling concentrated HF, and use in a fume hood. At any concentration chemical splash goggles should be the minimum eye protection because of the ability of HF to cause blindness.

Skin

Laboratory coats must also be worn. If working with larger volumes of concentrated HF an acid-resistant apron e.g. natural rubber or neoprene should also be worn.

Nitrile or butyl gloves are typically worn when working with HF, but a manufacturer’s glove selection guide should be consulted when selecting a glove for HF.

Gloves must be checked for leaks prior to use. Double gloving with a second pair of nitrile gloves can protect against leaks.

If gloves become contaminated with HF, they must be removed immediately, hands washed, and hands checked for any sign of contamination.

Storage of HF:

Store all solutions of HF in properly labelled, chemically compatible containers (e.g. polyethylene, polypropylene, or Teflon, and store separately from metals, concrete, glass, strong bases, sodium hydroxide, potassium hydroxide, and ceramics.

Never store in metal or glass container (or other silicon containing bottle).

Periodically check the condition of the container (plastic containers become brittle over time). Store HF containers in a secondary container, such as a tray, in a well-ventilated cabinet, separate from incompatible chemicals such as bases, metals and organic compounds.

Spills procedures:

All spills of HF solution presents a hazard so precautions must be taken to contain potential spills as far as possible. Small spills can be cleaned, with proper precautions, by the user. When using HF solutions spill kits should be readily available.

Sodium carbonate (soda, ash), sodium bicarbonate, lime, or a spill absorbent material (specified for use with HF by the manufacturer) should be used for cleaning spills.

Spill kits that contain cat litter or sand must not be used as HF reacts with silica to produce silicon tetrafluoride, a toxic gas.

E. Work with Nano-materials

Potential safety, health or environmental hazards associated with nano-scale materials is currently an area of active research, however recent results do indicate that certain forms of carbon nano-tubes do present health hazards.

HSE in collaboration with various universities have produced the document “Working Safely with Nanomaterials (link opens in a new window)”. The guidance in this document should be followed. Additional information is also available from the HSE website (link opens in a new window).

SHE Group should be informed of any work involving nano-materials prior to first use.

​F. Work with Cadmium and its compounds

Hazards from Cadmium and its compounds are well known and the HSE document "Cadmium and you" provides a useful summary. However specific attention should be paid where cadmium or cadmium compounds are heated in vacuum, where there is a considerable risk of sublimation causing contamination throughout any vacuum system.