NIOSH Publication No. 2005-151:

NIOSH Pocket Guide to Chemical Hazards

September 2005

Molybdenum

CAS
7439-98-7

Mo

RTECS
QA4680000
Synonyms & Trade Names

Molybdenum metal
DOT ID & Guide

Exposure
Limits

NIOSH REL: See Appendix D
OSHA PEL*: TWA 15 mg/m3 [*Note: The PEL also applies to other insoluble molybdenum compounds (as Mo).]
IDLH
5000 mg/m3 (as Mo) See: 7439987
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, 7301, 7303, 9102; OSHA ID121, ID125G
See: NMAM or OSHA Methods
Personal Protection & Sanitation
(See protection)
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 quarter-mask respirator. Click here for information on selection of N, R, or P filters.
Up to 150 mg/m3:
(APF = 10) Any particulate respirator equipped with an N95, R95, or P95 filter (including N95, R95, and P95 filtering facepieces) except quarter-mask respirators. The following filters may also be used: N99, R99, P99, N100, R100, P100. Click here for information on selection of N, R, or P filters.
(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 high-efficiency particulate filter.
Up to 750 mg/m3:
(APF = 50) Any air-purifying, full-facepiece respirator with an N100, R100, or P100 filter. Click here for information on selection of N, R, or P filters.
(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 an N100, R100, or P100 filter. Click here for information on selection of N, R, or P filters./Any appropriate escape-type, self-contained breathing apparatus
Important additional information about respirator selection
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   See MEDICAL TESTS: 0150