Thorium has slight radioactivity and emits alpha particles and occasionally some Beta and Gamma radiation. The levels are extremely low and external exposure risk is low. However, when ingested or inhaled this risk is increased.
Because welders need to grind the tips to prepare the rod for welding this creates dust particles that can be inhaled or ingested. It is recommended to wear appropriate safety gear as laid out in welding procedures.
Thoriated tungsten is recommended to be stored in a steel box.
There is now a choice of non-radioactive tungsten. VGD V3