HSE Exposure to Cadmium in Silver Soldering or Brazing (EIS31)

LEVCentral Expert Commentary

Cadmium has historically been added to certain silver brazing alloys because it lowers the melting temperature and improves the flow characteristics of the filler metal. However, when cadmium-containing alloys are heated above their melting point they produce cadmium oxide fume, an extremely toxic airborne contaminant that presents serious health risks to workers. For this reason, the use of cadmium in brazing alloys has been significantly restricted across Europe, with only limited exemptions remaining for certain aerospace, defence and safety-critical applications.

HSE Engineering Information Sheet EIS31 explains the hazards associated with cadmium-containing silver solders and sets out the precautions required where their use cannot be avoided. The guidance is aimed at employers, supervisors and workers involved in silver soldering (hard soldering) and brazing operations, as well as those repairing or dismantling components that may contain cadmium-bearing filler materials.

From an LEV perspective, this guidance reinforces one of the fundamental principles of occupational hygiene: metal fumes must be captured at source before they reach the operator’s breathing zone. Cadmium oxide fume particles are extremely small and remain airborne for prolonged periods. General ventilation alone is unlikely to provide adequate protection, making properly designed Local Exhaust Ventilation (LEV) essential wherever cadmium-containing brazing materials are used.

The guidance also reminds employers that engineering controls should be supported by suitable risk assessment, competent training, health surveillance where appropriate and the selection of cadmium-free alternatives whenever reasonably practicable.

View Original HSE Guidance

Key Learning Points

Cadmium has been widely phased out of silver brazing alloys because of its serious health effects, although limited exemptions remain for specific applications.
Heating cadmium-containing alloys produces highly toxic cadmium oxide fumes.
Acute exposure may cause:
- Eye, nose and throat irritation.
- Coughing and breathlessness.
- Delayed lung damage.
- Severe exposure may lead to acute pneumonitis and can be fatal.
Long-term exposure may damage the lungs and kidneys.
Wherever possible, cadmium-free silver brazing alloys should be selected.
Effective Local Exhaust Ventilation (LEV) should be provided where cadmium-containing brazing materials are used.
LEV should be thoroughly examined, tested and maintained to ensure continued effectiveness.
Workers should receive suitable information, instruction and training regarding cadmium hazards.
Appropriate respiratory protective equipment (RPE) may be required where exposure cannot be adequately controlled by engineering measures alone.

Source Document Information

Organisation: Health and Safety Executive (HSE)

Document: EIS31 – Exposure to Cadmium in Silver Soldering or Brazing

Series: Engineering Information Sheet

Document Type: HSE Guidance

Primary Topics: Cadmium, Silver Brazing, Hard Soldering, Welding Fume, LEV, COSHH

Audience: Brazing Engineers, Welders, Maintenance Engineers, LEV Designers, Occupational Hygienists, Health & Safety Professionals and Duty Holders.

Further Resources

Recommended Learning

Thought Leadership

Cadmium is an excellent example of how advances in occupational hygiene have influenced engineering practice. A material once valued for its metallurgical properties is now recognised as presenting unacceptable health risks in many applications, leading to the development of safer cadmium-free alternatives.

Where cadmium-containing alloys remain in use, the priority must be to prevent workers from inhaling cadmium oxide fume. Effective source capture using well-designed LEV, supported by competent commissioning, regular maintenance and Thorough Examination & Testing, remains one of the most reliable engineering controls available.

This guidance also highlights a broader lesson for LEV professionals: selecting a less hazardous material is often the most effective control measure of all, demonstrating the importance of considering substitution before relying solely on engineering controls.