Reference Source

Methylene bis(phenylisocyanate); MDI; diphenylmethane diisocyanate — CAS 101688 — workplace exposure limit

What is the pel (ppm) for Methylene bis(phenylisocyanate); MDI; diphenylmethane diisocyanate — CAS 101688 — workplace exposure limit?

For Methylene bis(phenylisocyanate); MDI; diphenylmethane diisocyanate, pel (ppm) is disputed: 0.005 per dir.ca.gov, (C)0.02 per osha.gov; pel (mg/m³) is disputed: 0.051 per dir.ca.gov, (C)0.2 per osha.gov; cas no. is 101688, verified against its source on 2026-09-29.

101688 | | Methylene bis(phenylisocyanate); MDI; diphenylmethane diisocyanate | 0.005 | 0.051

— dir.ca.gov, retrieved 2026-08-05

0.005
The most of this substance workplace air may legally contain, averaged over an 8-hour shift — OSHA's permissible exposure limit (PEL), in parts per million, from the agency's own table row quoted below. Where federal OSHA and Cal/OSHA disagree, both limits are stated, each with its own agency's table row as evidence. NIOSH's number, where there is one, is shown separately: it is a recommended limit, not a legal one, and it is often the strictest of the three.
Sourcedir.ca.gov
Verified
Review by
DatasetUS workplace chemical exposure limits: federal OSHA, Cal/OSHA and NIOSH, side by side
Substance
Methylene bis(phenylisocyanate); MDI; diphenylmethane diisocyanate verified
CAS No.
101688 verified
PEL (ppm)
0.005 sources disagree
PEL (mg/m³)
0.051 sources disagree
NIOSH REL (ppm)
0.005 per cdc.gov
NIOSH REL (mg/m³)
TWA 0.05 per cdc.gov

What cdc.gov says

NIOSH REL TWA 0.05 mg/m3 (0.005 ppm) C 0.2 mg/m3 (0.020 ppm) [10-minute]

— cdc.gov, retrieved 2026-09-08

Substance

CDC - NIOSH Pocket Guide to Chemical Hazards - Methylene bisphenyl isocyanate

CAS No.

CAS No. 101-68-8

The same source also states

101688 | | Diphenylmethane diisocyanate; see Methylene bis(phenylisocyanate)

— dir.ca.gov, retrieved 2026-08-05

The same source also states

101688 | | MDI; see Methylene bis(phenylisocyanate)

— dir.ca.gov, retrieved 2026-08-05

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)

dir.ca.gov says pel (ppm) is 0.005, as of 2026-08-05.

101688 | | Methylene bis(phenylisocyanate); MDI; diphenylmethane diisocyanate | 0.005 | 0.051

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

osha.gov says pel (ppm) is (C)0.02, as of 2026-08-05.

Methylene bisphenyl isocyanate (MDI) | 101-68-8 | (C)0.02 | (C)0.2 | - |

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

PEL (mg/m³)

dir.ca.gov says pel (mg/m³) is 0.051, as of 2026-08-05.

101688 | | Methylene bis(phenylisocyanate); MDI; diphenylmethane diisocyanate | 0.005 | 0.051

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

osha.gov says pel (mg/m³) is (C)0.2, as of 2026-08-05.

Methylene bisphenyl isocyanate (MDI) | 101-68-8 | (C)0.02 | (C)0.2 | - |

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

Sources

Last verified against source: . Due for re-check by . This page as Markdown · OKF bundle · full dataset as JSON.

What is the OSHA exposure limit for this substance?Find the exposure limit for a substance in workplace air — federal OSHA, California and NIOSH, side by side.

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