has set the legal limit (permissible exposure limit) for tantalum exposure in the workplace as 5 mg/m3 over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 5 mg/m3 over an 8-hour workday and a short-term limit of 10 mg/m3. At levels of 2500 mg/m3, tantalum dust is immediately dangerous to life and health. References External links Tantalum-Niobium International Study Center CDC – NIOSH Pocket Guide to Chemical Hazards Biomaterials Chemical elements with body-centered cubic structure Chemical elements Native element minerals Noble metals Refractory metals Transition metals