Dermal uptake study with 4,4'-diphenylmethane diisocyanate led to active sensitization

Area of Science:

• Occupational Dermatology
• Chemical Sensitization
• Toxicology

Background:

• Investigated dermal uptake of 4,4 -diphenylmethane diisocyanate (4,4 -MDI).
• Two volunteers applied 2.0% 4,4 -MDI in petrolatum, developing eczematous dermatitis.
• Surface concentration was 800 µg/cm(2).

Purpose of the Study:

• To determine if dermal application of 4,4 -MDI caused active sensitization.
• To assess the potential for cross-reactivity with related chemicals.

Main Methods:

• Chemical analysis of 4,4 -MDI preparation and unabsorbed amount using liquid chromatography-mass spectrometry.
• Patch testing volunteers with serial dilutions of 4,4 -MDI and potential cross-reactants: 4,4 -diaminodiphenylmethane (4,4 -MDA), p-phenylenediamine (PPD), and dicyclohexylmethane-4,4 -diisocyanate (DMDI).

Main Results:

• Patch tests indicated active sensitization to 4,4 -MDI, evidenced by positive reactions to 4,4 -MDA.
• No positive reactions to PPD or DMDI were observed.
• Chemical analysis confirmed the applied concentration and revealed approximately 70% of 4,4 -MDI remained unabsorbed.

Conclusions:

• Dermal application of 4,4 -MDI induced active sensitization.
• Sensitization extended to 4,4 -MDA, a known marker for 4,4 -MDI allergy.
• The study highlights the risk of dermal sensitization from 4,4 -MDI exposure.