Isophorone — CAS 78-59-1 — workplace exposure limit
What is the pel (ppm) for Isophorone — CAS 78-59-1 — workplace exposure limit?
For Isophorone, pel (ppm) is disputed: 25 per osha.gov, 4 per dir.ca.gov; pel (mg/m³) is disputed: 140 per osha.gov, 23 per dir.ca.gov; cas no. is 78-59-1, verified against its source on 2026-08-05.
Isophorone | 78-59-1 | 25 | 140 | - |
— osha.gov, retrieved 2026-08-05
- Substance
- Isophorone verified
- CAS No.
- 78-59-1 verified
- PEL (ppm)
- 25 sources disagree
- PEL (mg/m³)
- 140 sources disagree
- NIOSH REL (ppm)
- TWA 4 per cdc.gov
- NIOSH REL (mg/m³)
- 23 per cdc.gov
What cdc.gov says
NIOSH REL TWA 4 ppm (23 mg/m3)
— cdc.gov, retrieved 2026-09-08
Substance
CDC - NIOSH Pocket Guide to Chemical Hazards - Isophorone
CAS No.
CAS No. 78-59-1
Sources disagree
More than one authority states this, and they do not state the same thing. Both are reproduced with the source each came from — deciding between them is yours, not ours.
PEL (ppm)
osha.gov says pel (ppm) is 25, as of 2026-08-05.
Isophorone | 78-59-1 | 25 | 140 | - |
https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1
dir.ca.gov says pel (ppm) is 4, as of 2026-08-05.
78591 | | Isophorone; 3,5,5-trimethyl-2-cyclohexene-1-one | 4 | 23
https://www.dir.ca.gov/title8/5155.html
PEL (mg/m³)
osha.gov says pel (mg/m³) is 140, as of 2026-08-05.
Isophorone | 78-59-1 | 25 | 140 | - |
https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1
dir.ca.gov says pel (mg/m³) is 23, as of 2026-08-05.
78591 | | Isophorone; 3,5,5-trimethyl-2-cyclohexene-1-one | 4 | 23
Sources
- osha.govhttps://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1
- cdc.govhttps://www.cdc.gov/niosh/npg/npgd0355.html
- dir.ca.govhttps://www.dir.ca.gov/title8/5155.html