Controlling Exposure to Hexavalent Chromium in Welding Fume
By Geoff Melton
Industrial Need
Welding fume has been classified as a carcinogen with hexavalent chromium (Cr VI) of particular concern. In arc welding and cutting it is produced by the conversion of trivalent chromium to Cr (VI) in the arc. The limit values for exposure have been reviewed and lower limits have been proposed. Consequently, the European Commission has proposed new limits which will become law. More stringent limits are already in place in some countries, although in others such reduced limits do not apply or there are no limits in place.
There are therefore concerns in industry about meeting lower limits, and a better understanding is required of how Cr (VI) is produced during welding and what control measures may be required to satisfy new legislation. This report collates relevant information on workplace exposure and its measurement, occupational exposure limits (OELs), control measures, and research needs.
Key findings
- Welders are being exposed to hexavalent chromium, which is classified as a carcinogen, from welding stainless steels and other alloys containing chromium.
- OELs are being reduced globally, and industry requires more information and guidance to ensure that these limits are complied with.
- Studies have shown that a wide range of exposures are possible and are affected by process and consumables as well as control measures in the workplace. As most studies took place on the shop floor with multiple processes being carried out, and welders possibly carrying out many tasks, it is unclear what welding process fumes they were exposed to.
- It is unclear whether high exposure levels are due to the process and parameters or simply the effectiveness of the controls in place. However, the studies have shown that welders and other staff are being exposed to welding fume containing Cr (VI) in excess of current and proposed OELs.
- Problems in measurement and analysis of hexavalent chromium on filter papers have been reported, and improved standards are required for specifying the procedures because, as OELs are reduced, more accurate procedures for monitoring exposure will be required.