# Methyl silicate — workplace exposure limit

For Methyl silicate, niosh rel (ppm) is TWA 1; niosh rel (mg/m³) is 6; cas no. is 681-84-5, verified against its source on 2026-09-08.

- **Substance:** Methyl silicate _(verified: appears in its own passage below)_
- **CAS No.:** 681-84-5 _(verified: appears in its own passage below)_
- **NIOSH REL (ppm):** TWA 1 _(verified: appears in the quote below)_
- **NIOSH REL (mg/m³):** 6 _(verified: appears in the quote below)_
- **PEL (ppm):** 1 _(per dir.ca.gov, not stated by the source above)_
- **PEL (mg/m³):** 6 _(per dir.ca.gov, not stated by the source above)_

## What the source says

> NIOSH REL TWA 1 ppm (6 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 - Methyl silicate

### CAS No.

> CAS No. 681-84-5

## What dir.ca.gov says

> 681845 | | Methyl silicate; tetramethyl silicate | 1 | 6

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

## Source

- https://www.cdc.gov/niosh/npg/npgd0428.html
- 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/).