Air oxidation of d-limonene (the citrus solvent) creates potent allergens.
Products containing as much as 95% of d-limonene are used for, e.g., degreasing metal before industrial painting and for cleaning assemblies. Experimental studies on the sensitizing potential of limonene show diverging results. In a previous study, we found that the sensitizing potential of d-limonene increased with prolonged air exposure. The aim of this study was to make further chemical analyses, to identify compounds formed by air exposure of d-limonene and to study their allergenic potential. d-limonene was found to be a sensitizer after prolonged exposure to air according to 2 Freund's complete adjuvant test (FCAT) experiments and 1 guinea pig maximization test (GPMT) study. No significant response was obtained to d-limonene not air exposed, even if the animals were sensitized to oxidized d-limonene. 5 main oxidation products of d-limonene were identified. (R)-(-)-carvone and a mixture of cis and trans isomers of (+)-limonene oxide were found to be potent sensitizers, while no significant reactions were obtained in the animals induced with a mixture of cis and trans isomers of (-)-carveol. It can be concluded that air oxidation of d-limonene is essential for its sensitizing potential, and that potent allergens are created.
Karlberg
A T
AT
Department of Occupational Dermatology, National Institute of Occupational Health, Solna, Sweden.
Magnusson
K
K
Nilsson
U
U
D000393:Air Pollutants / Q000009:adverse effects; D000818:Animals; D002849:Chromatography, Gas; D000081005:Cyclohexane Monoterpenes; D053138:Cyclohexenes; D006168:Guinea Pigs; D000077222:Limonene; D039821:Monoterpenes; D010084:Oxidation-Reduction; D010328:Patch Tests; D012997:Solvents / Q000009:adverse effects / Q000737:chemistry*; D013729:Terpenes / Q000009:adverse effects / Q000737:chemistry* / Q000302:isolation & purification
D000393:Air Pollutants; D000081005:Cyclohexane Monoterpenes; D053138:Cyclohexenes; D039821:Monoterpenes; D012997:Solvents; D013729:Terpenes; C075856:carveol; D000077222:Limonene