# 2,4-D — workplace exposure limit

For 2,4-D, niosh rel (mg/m³) is TWA 10; cas no. is 94-75-7, verified against its source on 2026-09-08.

- **Substance:** 2,4-D _(verified: appears in its own passage below)_
- **CAS No.:** 94-75-7 _(verified: appears in its own passage below)_
- **NIOSH REL (mg/m³):** TWA 10 _(verified: appears in the quote below)_
- **PEL (mg/m³):** 10 _(per dir.ca.gov, not stated by the source above)_

## What the source says

> NIOSH REL TWA 10 mg/m3

## 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 - 2,4-D

### CAS No.

> CAS No. 94-75-7

## What dir.ca.gov says

> 94757 | | 2,4-D;2,4-dichlorophenoxyacetic acid | -- | 10

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

## What osha.gov says

> 2,4-D (Dichlorophenoxyacetic acid) | 94-75-7 | - | 10 | - |

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

## Source

- https://www.cdc.gov/niosh/npg/npgd0173.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/).