The question of “what percentage of welders get cancer” cannot be answered with a single, definitive number because cancer risk is highly individualized and variable. Public health data does not track a uniform percentage due to the wide range of factors influencing exposure, making a simple statistic misleading. Instead, researchers focus on the increased risk—or relative risk—that welders face compared to the general population. This risk depends heavily on the duration of a welder’s career, the intensity of their exposure to fumes, and whether they use proper protective equipment.
Understanding the Difficulty in Quantifying Cancer Risk
A precise percentage for cancer incidence among welders is unavailable because of the complexity of occupational exposure data. Cancer development involves a significant latency period, often decades, which complicates linking a diagnosis back to a job held years earlier. Furthermore, studies must account for important co-factors that independently elevate cancer risk, such as tobacco smoking and asbestos, which have often been present in the same work environments as welding.
The intensity and composition of welding fumes vary drastically depending on the specific metal being welded and the technique used, meaning exposure is not standardized across all welders. For example, a welder working on mild steel has a different exposure profile than one working on stainless steel, which contains different metallic compounds. Due to these variables, epidemiological studies report a range of excess risk, with some meta-analyses suggesting a 20% to 40% increased risk of lung cancer for welders compared to non-welders. The International Agency for Research on Cancer (IARC) classified welding fumes and the ultraviolet (UV) radiation from welding arcs as Group 1 carcinogens in 2017, meaning they are carcinogenic to humans.
Specific Cancers Linked to Welding Exposure
Evidence links welding exposure to an increased risk of lung cancer. Chronic inhalation of welding fumes directly targets the respiratory system, leading to a higher incidence of pulmonary malignancies. Some studies have reported welders having a 16% greater risk of lung cancer compared to the unexposed population, even after controlling for smoking.
Exposure to the intense UV radiation emitted by the welding arc is directly associated with ocular melanoma, a rare but serious cancer of the eye. This risk is present even with brief, unprotected exposure to the arc. Beyond the respiratory system, evidence suggests an elevated risk for urinary tract cancers, specifically kidney and bladder cancer. One population-based study found welders had a 30% greater risk of kidney cancer and a 40% greater risk of bladder cancer compared to non-welders.
Mechanisms of Carcinogenic Exposure in Welding
Carcinogenic exposure in welding arises from two main sources: fine particulate matter in the fumes and the intense energy of the welding arc. Welding fumes are a complex aerosol containing ultrafine particles that can penetrate deep into the lungs and enter the bloodstream. These particles are typically metallic oxides and silicates, which are formed when vaporized metal condenses.
Specific metallic elements within the fumes are known carcinogens, including hexavalent chromium and nickel when welding stainless steel. Hexavalent chromium is highly toxic and causes oxidative stress and DNA damage in cells, a mechanism that can lead to cancer. The intense heat also generates toxic gases, such as ozone and nitrogen oxides, which are powerful respiratory irritants and damaging agents.
Occupational Exposure Reduction Strategies
Controlling exposure to welding hazards relies on a hierarchy of controls, prioritizing engineering solutions over personal protection. Local Exhaust Ventilation (LEV) is the most effective engineering control, utilizing systems like fume extractor guns or movable capturing hoods placed close to the welding point to remove fumes at the source. General workshop ventilation is also necessary to dilute residual contaminants that escape source capture.
Respiratory protection is used when ventilation cannot reduce airborne contaminants to safe levels. Welders should wear appropriately rated respirators, with filter types selected based on the metals and gases present. Proper work practices also mitigate risk, such as cleaning base metals to remove toxic surface coatings before welding and positioning oneself to stay upwind when welding outdoors. Welders must also use welding helmets equipped with auto-darkening filters and wear flame-resistant clothing to shield the skin from UV radiation exposure.