Occupational dermatitis from exposure to polyurethane chemicals.

Area of Science:

• Allergy and Immunology
• Occupational Health
• Dermatology

Background:

• Occupational contact with polyurethane (PU) chemicals can lead to allergic contact dermatitis, distinct from asthma.
• Previous diagnoses of allergic contact dermatitis from PU chemicals were documented between 1974 and 1990.

Observation:

• Six cases of allergic contact dermatitis due to PU chemical exposure were identified.
• Detailed case studies of three patients revealed allergies to multiple diisocyanates (DICs), including 4,4'-diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), and 1,6-hexamethylene diisocyanate (HID), as well as diaminodiphenylmethane (MDA).
• Three patients were sensitized by MDI exposure, with two reacting to both MDI and MDA, and one also to TDI.

Findings:

• One patient reacted solely to MDA, suggesting it may form from MDI hydrolysis or indicate primary sensitization to MDA with cross-allergy to MDI.
• Patch tests using 2% MDI and TDI in petrolatum (pet.) were initially recommended.
• Stability tests showed positive reactions to MDI and TDI at 1.5% pet. concentrations even after 5.5 and 15.5 months, indicating the longevity of test substance efficacy.

Implications:

• For suspected PU chemical allergy, patch testing should include MDA, MDI, and TDI (1.5-2% pet.).
• Test substances for diisocyanates remain effective for over a year.
• An allergy to MDA may indicate exposure to MDI within PU chemicals.