# NIOSH Pocket Guide to Chemical Hazards
Molybdenum | CAS 7439-98-7
Mo | RTECS QA4680000
Synonyms & Trade Names Molybdenum metal | DOT ID & Guide
Exposure Limits | NIOSH REL*: See Appendix D [*Note: The REL also applies to other insoluble molybdenum compounds (as Mo).]
OSHA PEL*†: TWA 15 mg/m3 [*Note: The PEL also applies to other insoluble molybdenum compounds (as Mo).]
IDLH 5000 mg/m3 (as Mo) | Conversion
Physical Description Dark gray or black powder with a metallic luster.
MW: 95.9 | BP: 8717°F | MLT: 4752°F | Sol: Insoluble
VP: 0 mmHg (approx) | IP: NA |  | Sp.Gr: 10.28
Fl.P: NA | UEL: NA | LEL: NA |
Combustible Solid in form of dust or powder.
Incompatibilities & Reactivities Strong oxidizers
Measurement Methods NIOSH 7300; OSHA ID121, ID125G
Personal Protection & Sanitation Skin: No recommendation Eyes: No recommendation Wash skin: No recommendation Remove: No recommendation Change: No recommendation | First Aid (See procedures) Eye: Irrigate immediately Breathing: Respiratory support Swallow: Medical attention immediately
Respirator Recommendations OSHA Up to 75 mg/m3: (APF = 5) Any dust and mist respirator^ Up to 150 mg/m3: (APF = 10) Any dust and mist respirator except single-use and quarter-mask respirators^/(APF = 10) Any supplied-air respirator Up to 375 mg/m3: (APF = 25) Any supplied-air respirator operated in a continuous-flow mode/(APF = 25) Any powered, air-purifying respirator with a dust and mist filter^ Up to 750 mg/m3: (APF = 50) Any air-purifying, full-facepiece respirator with a high-efficiency particulate filter/(APF = 50) Any supplied-air respirator that has a tight-fitting facepiece and is operated in a continuous-flow mode/(APF = 50) Any powered, air-purifying respirator with a tight-fitting facepiece and a high-efficiency particulate filter/(APF = 50) Any self-contained breathing apparatus with a full facepiece/(APF = 50) Any supplied-air respirator with a full facepiece Up to 5000 mg/m3: (APF = 1000) Any supplied-air respirator operated in a pressure-demand or other positive-pressure mode Emergency or planned entry into unknown concentrations or IDLH conditions: (APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode/(APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus Escape: (APF = 50) Any air-purifying, full-facepiece respirator with a high-efficiency particulate filter/Any appropriate escape-type, self-contained breathing apparatus
Exposure Routes inhalation, ingestion, skin and/or eye contact
Symptoms In animals: irritation eyes, nose, throat; anorexia, diarrhea, weight loss; listlessness; liver, kidney damage
Target Organs Eyes, respiratory system, liver, kidneys
See also: INTRODUCTION