Exposure to welding Fumes

The International Agency for Research on Cancer (IARC) has recently published Monograph 118. Welding fumes are included here as a Group 1 carcinogen – a topic which has elicited discussion and concern in manufacturing industries. Fronius was keen to look at this area more closely. With this in mind, Geoff Melton , Chair of the Occupational Health and Safety Committee at the International Institute of Welding (IIW) and expert in arc welding processes was invited for an interview.

Geoff Melton: Since graduating from the University of St Andrews in Scotland with a degree in Physics and Electronics, Geoff Melton has worked in welding research and development for nearly 40 years. He is a Technology Manager at TWI in Cambridge, UK, and is the Chairman of the Technical Commission VIII for Health, Safety and Environment of the International Institute of Welding (IIW). The recommendations issued by the IIW play an important role in the definition of national and international regulations - for example on the subject of welding fumes.

Mr. Melton, in your opinion, what has caused the IARC – an institution of the WHO – to reclassify the risk level of welding fumes?

The IARC is a committee of experts that looked at all published information on this topic, which includes exposure data, studies on cancer in humans and animals, mechanistic and other data. Based on “substantial new evidence” they concluded that all welding fume, regardless of composition, should be upgraded from “possibly carcinogenic to humans” (Group 2B) to “carcinogenic to humans” (Group 1). In the past it was difficult to separate out the effects of exposure to asbestos and smoking from the effects of welding fume. But now, positive associations are found after adjusting for exposure to these substances. Consequently, they concluded that there is “sufficient evidence in humans” that welding fumes cause lung cancer and limited evidence for kidney Cancer.

Could this lead to restrictions or even a complete ban on exposure to welding fumes?

The IARC examines the evidence and draws conclusions on the carcinogenicity of substances. They do not set limits or regulations. It is the responsibility of other international and national bodies to examine the conclusions and set limits for exposure. Provided welding fume exposure can be controlled to within limits, welding can continue to take place. However, as limits are reduced, exposure control becomes more difficult. Some countries have occupational exposure limits for welding fume, but others control fume by individual limits for the composition, e.g. chromium, nickel and manganese.

We should remember that some other common substances, for example diesel engine fumes, are classified as carcinogens by the IARC. These substances are not banned, but we recommend moderation and limits for consumption or exposure.

What effects do these latest developments have on your work at the IIW?

It is important to remember that IARC publications draw conclusions based on the evidence examined and are not legal documents. However, Monograph 118 is a very important document, and we must study it and respond accordingly. The welding industry looks to the IIW for guidance, so we are preparing a new statement on the carcinogenicity of welding fume which should be published later this year.

Members of the IIW will continue to review and research welding fume, with the aim of a better understanding, so that we can implement measures to reduce the impact of these findings. One example is the formation of hexavalent chromium in welding fume, which is a carcinogen, for which the mechanism is not fully understood.

The IIW has not yet made an official statement. What would be your personal recommendation?

I think it is best practice to reduce welders’ exposure to fume to a level as low as reasonably practicable. There is a hierarchy of controls for reducing exposure, from minimizing the amount of fume produced from the process, using fume extraction equipment and if necessary wearing respiratory protection equipment. In some countries the fume from stainless steel has been controlled better than that from other alloys. The message now is that all welding fume should be treated the same.

When it comes to minimizing welding fumes, how much of an influence can we have, as an innovative manufacturer of process-optimized welding Systems?

Most of the welding fume comes from the filler material, so developments in filler materials can reduce the amount and composition of the fume emitted from the process. But control of the arc by the power source is also important. Generally, a more stable arc will produce less fume, and more precise control of the arc by the power source provides that stability. Most of the fume is generated from vaporization from the molten droplet, so control of the welding parameters to minimize molten drop temperature should have an effect on fume Emission.

Nevertheless, welding fumes will always be unavoidable to a certain degree. For this reason, we offer a wide range of products such as welding helmets with a fresh air supply and fume extraction torches. However, not everybody uses them. Why do you think this is the case?

I think that fume extraction torches have a bad reputation, so companies do not see them as a viable method to control welding fume. There are concerns that they disturb the shielding gas, leading to poor quality welds, and the original designs were heavy and bulky. Manufacturers such as Fronius need to convince their customers that the new generation of extraction torches are a good alternative to local exhaust ventilation (LEV).

As a manufacturer, is there more we can do to increase safety?

The best solution is to prevent welders being exposed to the fume at source, so mechanization and robotics have a part to play as they remove the welder from the fume.

Our company is already well-positioned in terms of robotic welding systems and automation. Nevertheless, there are still many manual welders around the world, and this will surely continue to be the case. What can we do to protect these People?

The most important thing is to raise awareness among welders about the hazards they face. We need to be more involved at the training stage and the trainer needs to inform participants about any risks as effectively as possible. This is the best way to reach young welders and ensure that health and safety measures are implemented in both theory and in practice.

My personal feeling is that welders are actually quite knowledgeable about the subject. Young welders are already recognizing the hazards and insisting on appropriate safety measures. For Fronius as a manufacturer, apart from producing improved fume control methods, there is still the need to refine welding processes to produce less fume at source.

Does IARC Monograph 118 signal the end of the welding Industry?

No, definitely not. We have been aware of the potential of welding fumes to cause cancer for many years and have good systems in place to control exposure to welding fume. This new classification by IARC emphasizes the need to continue to develop new approaches and systems to keep welders’ exposure to fume to a Minimum.

Our top priority must be to continually reduce the level of risk. I believe that it is in this way that we can secure the long-term future of the Industry.