Background
In March 2017, the International Agency for Research on Cancer (IARC) reclassified welding fumes from “possibly carcinogenic” to “carcinogenic to humans”. Metalworkers are now considered at risk of long-term illness from prolonged exposure to welding fumes.
Workers who are regularly exposed to welding fumes have an increased incidence of lung cancer and pneumonia related to lifelong cumulative exposure. There is also mounting evidence that exposure to welding fumes increase the risk of welders developing kidney cancer.
In Australia, the occupational exposure standard for welding fumes (time-weighted average concentration when measured inside a welder’s helmet) is:
- 5 mg/m3 (for an 8-hour workday)
- 3.5 mg/m3 (for a 12-hour workday).
Exposure standards vary throughout the world. European occupational exposure standards are generally more precautionary (1.25 mg/m3 in Germany and 1 mg/m3 in the Netherlands, for an 8- hour workday).
The current Australian exposure standard was set considering short term illness (metal fume fever) as the primary consequence of welding fume exposure. However, the reclassification of welding fumes as a known carcinogen validates concerns related to long-term cumulative exposures, with potential for cancers occurring decades after the workplace exposures.
About 12 per cent of the welding fume samples submitted to the the Department over the last year exceeded the Australian exposure standard. This level of exceedence has been relatively consistent over the past 25 years (refer graph).
The Australian workplace exposure standard for welding fumes is currently being reviewed by Safe Work Australia to ensure it protects workers exposed to welding fumes against health effects.
Summary of hazard
Inhaled welding fumes are associated with chronic inflammation and weakened immune function that may increase the body’s vulnerability to infections or tumours.
Metal fumes associated with welding that pose long-term health risks include:
- nickel, chromium and cadmium – known carcinogens
- manganese – can cause manganism (a Parkinsonian neurological condition)
- aluminium and heavy metals, such as lead – linked to neurological diseases
- molybdenum trioxide and indium tin oxide – classified as Group 2B carcinogens ("possibly carcinogenic to humans").
Contributory factors
The airborne hazards associated with welding vary depending on the working environment, type of metal and flux, and the chemical nature of paints or cleaners on weld surfaces. Exposure of workers to welding fumes is significantly increased when:
- there is inadequate local exhaust ventilation to draw the fumes away from the breathing zone of the worker
- there is no, or inadequate, personal protective equipment (PPE) used to protect the worker from particulates and gases produced during welding
- welders remove the helmet shield prior to complete dispersion of the fume cloud.