Dicyclohexylmethane diisocyanate H12MDI

Aliphatic diisocyanates can have strong, adverse skin irritation effects and two are well known for this problem, namely dicyclohexylmethane diisocyanate (H12MDI) (Desmodur W by Bayer) and hexamethylene diisocyanate (HDI). Usually care in handling and good hygiene prevents undue problems. Occasionally a more serious effect has been observed in one instance a chemical worker exposed her face to the hot vapour of dicyclohexylmethane diisocyanate and within 24 h her head had swollen to 20% of its original size and characteristic red spots with a white centre were present over the exposed area. Recovery took place slowly over a period of 3 weeks with cortisone-type ointment treatments. Her central nervous system was also affected and took some months to become normal. This was a very unusual and unique incident and is recorded to show that occasionally the unexpected human response can occur with diisocyanates. 

Speckhard T, et al. Properties of polyisobutylene polyurethane block copolymers 3. Hard segments based on 4, 4 -dicyclohexylmethane diisocyanate (H12MDI) and butane diol. Polymer 1985 26(l) 70-8. 

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