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Chemical Sampling Information (CSI)
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General Description

Synonyms: Metallic molybdenum

OSHA IMIS Code Number: 1790

Chemical Abstracts Service (CAS) Registry Number: 7439-98-7

NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: QA4680000

NIOSH Pocket Guide to Chemical Hazards - Molybdenum (as Mo), Insoluble Compounds (Total Dust): Physical description, chemical properties, potentially hazardous incompatibilities, and more



Exposure Limits and Health Effects

Exposure Limit

Limit Values

HE Codes

Health Factors and Target Organs

OSHA Permissible Exposure Limit (PEL) - General Industry
See 29 CFR 1910.1000 Table Z-1

15 mg/m3

HE16

 

Mild eye, nose, throat, and skin irritation

 

OSHA PEL - Construction Industry
See 29 CFR 1926.55 Appendix A

15 mg/m3

HE16

Mild eye, nose, throat, and skin irritation

OSHA PEL - Shipyard Employment
See 29 CFR 1915.1000 Table Z-Shipyards

15 mg/m3

HE16

Mild eye, nose, throat, and skin irritation

National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL)

Not established

 

 

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) (2003)

10 mg/m3 (inhalable)

3 mg/m3 (respirable)

HE16

Mild eye, nose, throat, and skin irritation
CAL/OSHA PELs

10 mg/m3 TWA
(total dust)

3 mg/m3 TWA (respirable)
HE16

Mild eye, nose, throat, and skin irritation

National Toxicology Program (NTP) carcinogenic classification: Not listed

International Agency for Research on Cancer (IARC): Not listed

U.S. Environmental Protection Agency (EPA) carcinogenic classification: Not listed

EPA Inhalation Reference Concentration (RfC): Not established

Agency for Toxic Substances and Disease Registry (ATSDR) Inhalation Minimal Risk Level (MRL): Not established

NIOSH Immediately Dangerous to Life or Health (IDLH) concentration: 5000 mg/m3 (as Mo)

Notes on Other Potential Health Effects and Hazards

  1. While molybdenum can be combustible, it is so only during specific conditions (NIOSH/IPCS 2006).
  2. In general, molybdenum toxicity is low, given that it is an essential element necessary for human health (ACGIH 2003).
  3. Certain forms of molybdenum appear to be more toxic than others. For instance, in some studies, molybdenum trioxide and ammonium molybdate have been shown to be more toxic than molybdenum disulfide, molybdenum dioxide, or metallic molybdenum (ACGIH 2003).
  4. A 1984 study of mining and metallurgy workers found exposures to 60 to 600 mg/m3 of molybdenum were associated with nonspecific symptoms such as weakness, fatigue, headache, and joint/muscle pain (ACGIH 2003).
  5. Other studies have linked molybdenum exposure to incidences of gout and bone disease, but the U.S. National Research Council (NRC) concluded that those associations were speculative at best (ACGIH 2003).
  6. The first human data on molybdenum and cancer was published in 1999, examining the link between molybdenum exposure and lung cancer. The findings raised the possibility that molybdenum could be a human carcinogen (ACGIH 2003).

Date last revised: 09/06/2012

Literature Basis

  • ACGIH: Documentation of the Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) - Molybdenum and Compounds. 2003.
  • NIOSH: Occupational Health Guideline for Molybdenum and Insoluble Molybdenum. September 1978.
  • NIOSH/IPCS: International Chemical Safety Cards - Molybdenum. October 10, 2006.
Monitoring Methods used by OSHA

Laboratory Sampling/Analytical Method (SLC1):
  • sampling media:Tared Low Ash Polyvinyl Chloride (LAPVC) filter
    maximum volume: 960 Liters
    minimum volume: 480 Liters
    maximum flow rate: 2.0 L/min
    current analytical method: Atomic Absorption Spectroscopy; AAS
    method reference: 2 (OSHA ID-121)
    sampling analytical error: 0.15
    method classification: Fully Validated
    alternate analytical method: Inductively Coupled Argon Plasma; ICP/DCP-AES
    method reference: 2 (OSHA ID-125G)
    sampling analytical error: 0.13
    method classification: Fully Validated
    note: If the filter is not overloaded, samples may be collected up to an 8-hour period.

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