# beta-Propiolactone — workplace exposure limit

For beta-Propiolactone, niosh rel, as stated is Ca See Appendix A; cas no. is 57-57-8, verified against its source on 2026-09-08.

- **Substance:** beta-Propiolactone _(verified: appears in its own passage below)_
- **CAS No.:** 57-57-8 _(verified: appears in its own passage below)_
- **NIOSH REL, as stated:** Ca See Appendix A _(verified: appears in the quote below)_
- **PEL (ppm):** 0.5 _(per dir.ca.gov, not stated by the source above)_
- **PEL (mg/m³):** 1.5 _(per dir.ca.gov, not stated by the source above)_

## What the source says

> NIOSH REL Ca See Appendix A

## 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 - beta-Propiolactone

### CAS No.

> CAS No. 57-57-8

## What dir.ca.gov says

> 57578 | | beta-Propiolactone, see Section 5209 | 0.5 | 1.5

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

## What osha.gov says

> beta-Propriolactone; see 1910.1013 | 57-57-8 | - | - | - |

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

## Source

- https://www.cdc.gov/niosh/npg/npgd0528.html
- https://www.dir.ca.gov/title8/5155.html
- https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1

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/).