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Methylene Diphenyl Diisocyanate (monomeric MDI) and polymeric MDI (PMDI) Quickview (CASRN 101-68-8, 9016-87-9)

Health assessment information on a chemical substance is included in IRIS only after a comprehensive review of toxicity data by U.S. EPA health scientists from several Program Offices, Regional Offices, and the Office of Research and Development.

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Status of Data for Methylene Diphenyl Diisocyanate (monomeric MDI) and polymeric MDI (PMDI)

File First On-Line: 05/01/1994; Last Significant Revision: 02/07/1998

Category (section)
Last Revised
Oral RfD Assessment No
Inhalation RfC Assessment Yes 02/07/1998
Carcinogenicity Assessment Yes 02/07/1998
  • 101-68-8
  • 1,1' - Methylenebis (4-isocyanatobenzene)
  • 4,4' - Diisocianato de difenilmetano (Spanish)
  • 4,4' - Diisocyanate de diphenylmethane (French)
  • 4,4' - Diisocyanathodiphenylmethane
  • 4,4' - Diphenylmethane dilsocyanate
  • 4,4' - Methylenebis (phenyl isocyanate)
  • 4,4' - Methylenediphenyl diisocyanate
  • 4,4' - Methylenediphenylene isocyanate
  • 4,4' - Methylenedi - p- phenylene diisocyanate
  • Benzene, 1,1' -methylenebis(4-isocyanato-
  • more...
Revision History
Date Section Description
02/07/1998 I.B., II., VI. Revised RfC, new carcinogenicity assessment
Chronic Health Hazard Assessments for Noncarcinogenic Effects

Reference Dose for Chronic Oral Exposure (RfD)

Not Assessed under the IRIS Program.

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Reference Concentration for Chronic Inhalation Exposure (RfC)

Critical Effect
Point of Departure*
Hyperplasia of olfactory epithelium BMC10 (HEC): 6 x10-2 mg/m3 100 6x10-4 mg/m3

* The Point of Departure listed serves as a basis from which the Inhalation RfC was derived. See Discussion of Conversion Factors and Assumptions for more details.

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Carcinogenicity Assessment for Lifetime Exposure
  • Weight-of-Evidence Characterization
    • D (Not classifiable as to human carcinogenicity)
    • Carcinogenic potential cannot be determined
  • Weight-of-Evidence Narrative:
    • Under U.S. EPA's 1996 Proposed Guidelines for Carcinogen Risk Assessment, the carcinogenic potential of MDI/PMDI would be characterized as "cannot be determined," but for which there is suggestive evidence that raises concern for carcinogenic effects.
    • This may be a synopsis of the full weight-of-evidence narrative. See IRIS Summary.

Quantitative Estimate of Carcinogenic Risk from Oral Exposure

  • Not Assessed under the IRIS Program.

Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure

  • Not Assessed under the IRIS Program.

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