Tantalum (Ta)

Tantalum (Ta) is a group 5 element, along with vanadium and niobium, and it always occurs in geologic sources together with the chemically similar niobium, mainly in the mineral groups tantalite, columbite, and coltan.

The chemical inertness and very high melting point of tantalum make it valuable for laboratory and industrial equipment such as reaction vessels and vacuum furnaces. It is used in tantalum capacitors for electronic equipment such as computers. It is being investigated for use as a material for high-quality superconducting resonators in quantum processors.

The metal is highly biocompatible and is used for body implants and coatings. Tantalum is widely used in surgery because of two unique characteristics of tantalum. Tantalum's hardness and ductility is useful in making sharp, durable surgical instruments and also for monofilament sutures. However, a completely unrelated use for tantalum in surgery arises from its unique ability to form a lasting and durable structural bond with human hard tissue, making it uniquely useful for bone and dental implants. Tantalum coatings are increasingly used in the construction of complex tantalum-coated titanium surgical implants due to the tantalum plating's ability to form a strong and biologically stable bond to hard tissue. An incidental consequence of its use for durable surgical implants is that tantalum implants are considered to be acceptable for patients undergoing MRI procedures because tantalum is a non-ferrous, non-magnetic metal.

People can be exposed to tantalum in the workplace by breathing it in, skin contact, or eye contact. The Occupational Safety and Health Administration (OSHA) 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. There is a paradox arising because of tantalum's ability to form a strong and permanent bond with bone tissue: at levels of 2500 mg/m3, tantalum dust becomes immediately dangerous to life and health if tantalum dust accidentally bonds with the wrong tissue.

Ref:

• Burke, Gerald L. (August 1940). "The Corrosion of Metals in Tissues; and An Introduction to Tantalum". Canadian Medical Association Journal. 43 (2): 125–128
• Cohen, R.; Della Valle, C. J.; Jacobs, J. J. (2006). "Applications of porous tantalum in total hip arthroplasty". Journal of the American Academy of Orthopaedic Surgeons. 14 (12): 646–55
• Paganias, Christos G.; Tsakotos, George A.; Koutsostathis, Stephanos D.; Macheras, George A. (2012). "Osseous integration in porous tantalum implants". Indian Journal of Orthopaedics. 46 (5): 505–13.
• Matsuno, H.; Yokoyama, A.; Watari, F.; Uo, M.; Kawasaki, T. (2001). "Biocompatibility and osteogenesis of refractory metal implants, titanium, hafnium, niobium, tantalum and rhenium. Biocompatibility of tantalum". Biomaterials. 22 (11): 1253–1262