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Mild Steel Welding Fume Reclassified as a Human Carcinogen

As a result of The International Agency for Research on Cancer (IARC) releasing new scientific evidence that exposure to mild steel welding fume can cause lung cancer and possibly kidney cancer in humans, mild steel welding fume has been reclassified as a human carcinogen by the Workplace Health Expert Committee.

The Health and Safety Executive (HSE) has released a safety alert for those undertaking welding activities, including mild steel, in any industry. In order to protect workers, the HSE is strengthening their enforcement of cancer-causing welding fumes with immediate effect.

HSE’s Construction Division is producing a briefing which will state: Prior to the change, duty holders would have had to assess the risk and put in appropriate controls depending on what they were cutting up and how coated it was with contaminants. However, the expectation in relation to these controls and any enforcement action has increased in line with that for mild steel – effectively from the same date.

Employers should now review their COSHH risk assessment if they are welding mild steel and did not have any exposure controls in place previously, to ensure they provide suitable control measures going forward.

Welding fume is a complex and varying mixture of airborne particles, vapours and gases which arise from the thermal manipulation of metal materials. The fume particles formed from the vaporisation of molten metal as well as by-product vapours and gases may cause a wide range of adverse health effects.

Control of exposure to carcinogenic fumes requires more effective engineering controls, such as local exhaust ventilation (LEV), which allows for at-source fume extraction thus preventing welding fume from spreading into the surrounding workplace and entering the worker’s breathing zone.

Indoor welding tasks require the use of LEV. If LEV is unable to control fume capture, then Respiratory Protective Equipment (RPE) is also required. Appropriate RPE should be also provided for welding outdoors.

Welders are more prone to lung infections, reduced lung function and may experience irritation of the throat and lungs. Welders may also experience flu like symptoms after welding (metal fume fever) which is usually linked to welding on galvanised metals, as well as mild steel.

This vast array of health effects is staggering and so the need for effective exposure controls is critical:

  • Suitable control measures must be applied, regardless of welding duration and including outdoors welding;

  • The employer must ensure welders are suitably instructed and trained in the use of any exposure controls (e.g. LEV, RPE);

  • All engineering controls should be correctly used, suitably maintained and subject to thorough examination and testing (if required under COSHH Regulation 9) and RPE must be subject to an RPE programme.

Our occupational hygienist can help you with your COSHH compliance by assessing your workers’ exposure to hazardous substances and also by undertaking examination of control measures in place to ensure continued performance or recommend improvements. If you would like to know more, or obtain a quote for Workplace Air Monitoring, please call 0800 0836458 or e-mail


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