 The US Occupational Safety and Health Administration ( <unk> ) has set the permissible exposure limit ( <unk> ) for cadmium at a time @-@ weighted average ( TWA ) of 0 @.@ <unk> ppm . The National Institute for Occupational Safety and Health ( <unk> ) has not set a recommended exposure limit ( <unk> ) and has designated cadmium as a known human <unk> . The <unk> ( immediately dangerous to life and health ) level for cadmium is 9 mg / m3 . 
