# Molybdenum — workplace exposure limit

For Molybdenum, niosh rel, as stated is See Appendix D; cas no. is 7439-98-7, verified against its source on 2026-09-08.

- **Substance:** Molybdenum _(verified: appears in its own passage below)_
- **CAS No.:** 7439-98-7 _(verified: appears in its own passage below)_
- **NIOSH REL, as stated:** See Appendix D _(verified: appears in the quote below)_
- **PEL (mg/m³):** 0.5(n) _(per dir.ca.gov, not stated by the source above)_

## What the source says

> NIOSH REL See Appendix D

## Where each value comes from

This source states these in separate places, so each value is shown with the passage that states it.

### Substance

> CDC - NIOSH Pocket Guide to Chemical Hazards - Molybdenum

### CAS No.

> CAS No. 7439-98-7

## What osha.gov says

> Molybdenum (as Mo) | 7439-98-7 | - | - | - |

Source: https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1

## What dir.ca.gov says

> 7439987 | | Molybdenum, insoluble compounds, as Mo | -- | 0.5(n)

Source: https://www.dir.ca.gov/title8/5155.html

## Source

- https://www.cdc.gov/niosh/npg/npgd0433.html
- https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1
- https://www.dir.ca.gov/title8/5155.html

Last verified: 2026-09-08. Review by: 2027-08-05.
Part of [US workplace chemical exposure limits: federal OSHA, Cal/OSHA and NIOSH, side by side](https://referencesource.org/workplace-exposure-limits/).