 Titanium is non @-@ toxic even in large doses and does not play any natural role inside the human body . Zirconium powder can cause irritation , but only contact with the eyes requires medical attention . OSHA recommends for zirconium are 5 mg / m3 time weighted average limit and a 10 mg / m3 short @-@ term exposure limit . Only limited data exists on the toxicology of hafnium . 
