Dictionary of Occupational Allergens: Chemical Structures, Sources and References

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.

7 patients were occupationally sensitized to dental composite resin products (DCR): 6 dental nurses and 1 dentist. All had a positive patch test to their DCR. 2 independent types of allergy were seen; (a) aromatic epoxy acrylate, and/or (b) aliphatic acrylates. 4 out of 5 patients reacted to BIS-GMA, the most widely used aromatic epoxy acrylate in DCR, but not the dentist. She and 2 dental nurses were allergic to aliphatic acrylates, including triethylene glycol dimethacrylate (TREGDMA) and triethylene diglycol diacrylate (TREGDA). 4 patients were allergic to epoxy resin (ER) (containing mainly MW 340), possibly an impurity in some DCR. 2 patients were also allergic to methyl methacrylate (MMA): the dentist, had been exposed to MMA, but the nurse's exposure was uncertain. 1 patient was also allergic to rubber gloves, 2 to rubber chemicals but not their gloves, and 5 to disinfectants used. diagnosis was delayed as long as 13 years in spite of previous patch testing. Dermatologists need to use the patients' own DCR and the (meth)acrylate series for patch testing. No dental nurses could continue their occupation, but the dentist could occasionally handle DCR if wearing PVC gloves. Dental personnel need to know about the risks of DCR, and use no-touch techniques and protective gloves.

d-Limonene, obtained as a by-product from the citrus juice industry, was introduced on the market as a more environmentally friendly defatting and cleaning agent than the traditionally used organic solvents. Autoxidation of d-limonene readily occurs to give a variety of oxygenated monocyclic terpenes that are strong contact allergens. The aim of the present study was to investigate the prevalence of contact allergy to air exposed d-limonene among dermatitis patients. A fraction consisting of d-limonene hydroperoxides was also tested. Screening with oxidized d-limonene will detect cases of allergic contact dermatitis. Additional cases were detected when testing with the fraction of limonene hydroperoxides. The proportion of positive patch test reactions to oxidized d-limonene was comparable to that seen for several of the allergens within the standard series. An increased use of d-limonene containing allergenic oxidation products in industry where high concentrations are used, as well as in domestic exposure, might result in contact sensitization and dermatitis. Patients reacting to d-limonene often reacted to fragrance mix, balsam of Peru and colophony in the standard series.