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  • Experimental delayed hypersensitivity following inhalation of dicyclohexylmethane-4,4'-diisocyanate: a concentration-response relationship.

Experimental delayed hypersensitivity following inhalation of dicyclohexylmethane-4,4'-diisocyanate: a concentration-response relationship.

Toxicology and applied pharmacology (1984-06-30)
J Stadler, M H Karol
ABSTRACT

Exposure of workers to low-molecular-weight chemicals has been associated with delayed-onset hypersensitivity reactions in both the skin and the respiratory tract. The use of two animal models to examine factors affecting the production of delayed hypersensitivity to dicyclohexylmethane-4,4'-diisocyanate (HMDI) is described. Guinea pigs were exposed to HMDI by a "head-only" method and mice in a "nose-only" procedure. All animals were subsequently tested for dermal sensitivity by topical challenge with the isocyanate. In both species, a concentration-response relationship and "no-effect" concentration was observed between chamber concentration of HMDI and (a) severity of the dermal response and (b) number of animals responding. Guinea pigs developed skin sensitivity following inhalation of 3 micrograms/liter or greater HMDI for 2 hr/day on 3 consecutive days. Inhalation of 1.25 micrograms/liter did not result in sensitization. Contact sensitivity was detected in BALB/cBy mice following inhalation of 17 micrograms/liter or greater HMDI. No reactions occurred as a result of exposure to 7 micrograms/liter or less HMDI. Dermal contact of the head, as would occur during inhalation exposures, also resulted in contact sensitization. Identification of the concentration-response relationship for contact sensitization following inhalation exposure implies that safe exposure levels can be proposed to prevent cases of dermal sensitization to HMDI.

MATERIALS
Product Number
Brand
Product Description

Supelco
HMDI, analytical standard
Sigma-Aldrich
4,4′-Methylenebis(cyclohexyl isocyanate), mixture of isomers, 90%