Thoriated TIG welding electrodes with 2 % thorium oxide (colour code red) are currently the most widely used electrodes worldwide. Thorium is however a radioactive element and as such represents a potential danger to health and environment. Thorium is a so-called "a-emitter," but when enclosed in a tungsten matrix, the "a" radiation emitted externally is negligible.
The danger to the welder arises when thorium oxide gets into the respiratory canals. This problem can occur during welding (vapours) as well as when grinding the electrode tip (grinding dust). In the near future, more stringent legal regulations regarding production, use and disposal of thoriated electrodes are expected. It is expected that TlG-welding electrodes containing thorium will disappear from the market in the foreseeable future, especially as an environmentally friendly and technically better solution is already available.