title: Combined effects of irritants and allergens. Synergistic effects of nickel and sodium lauryl sulfate in nickel- sensitized individuals.
abstract: Knowledge of the combined effects of irritants and allergens is of interest with respect to accurate risk assessment. The threshold for elicitation of allergic contact dermatitis in previously sensitized individuals may theoretically be markedly influenced by the simultaneous presence of irritants and allergens. Combined exposures have, however, only been studied infrequently. In the present study, the combined effect of an irritant and an allergen was evaluated in a dose-response designed experimental study. 20 nickel-sensitized subjects were exposed to patch testing with varying concentrations of NiCl2 (nickel chloride) and sodium lauryl sulfate (SLS) alone and in combination. Evaluation of skin reactions was performed by colorimetry, measurement of transepidermal water loss and clinical evaluation, and the data were analyzed by logistic dose-response models. A synergistic effect was found of combined exposure to NiCl2 and SLS, as compared to each of the substances applied separately, as evaluated by colorimetry and clinical scoring. This means that the effect produced by the combined exposure was substantially greater than the effect produced by either of the substances alone. A synergistic effect of combined exposure on skin barrier impairment was not found, since the barrier function is significantly influenced by SLS-exposure only and not by NiCl2. Concentration limits are used by industry and government agencies to protect consumers. The present results clearly illustrate that elicitation thresholds and concentration limits may be influenced considerably by combined exposure to allergens and irritants.
authors.affiliation: The National Allergy Research Centre for Consumer Products, Department of Dermatology, University of Copenhagen, Sharnbrook, Bedford, UK. t.agner@dadlnet.dk
authors.forename: Tove
authors.initials: T
authors.lastname: Agner
authors.forename: Jeanne Duus
authors.initials: JD
authors.lastname: Johansen
authors.forename: Lene
authors.initials: L
authors.lastname: Overgaard
authors.forename: Aage
authors.initials: A
authors.lastname: Vølund
authors.forename: David
authors.initials: D
authors.lastname: Basketter
authors.forename: Torkil
authors.initials: T
authors.lastname: Menné
mesh_terms: D000328:Adult; D000485:Allergens / Q000008:administration & dosage / Q000009:adverse effects*; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005260:Female; D006801:Humans; D007509:Irritants / Q000008:administration & dosage / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009532:Nickel / Q000008:administration & dosage / Q000009:adverse effects*; D010328:Patch Tests / Q000592:standards*; D012967:Sodium Dodecyl Sulfate / Q000008:administration & dosage / Q000009:adverse effects*; D014870:Water Loss, Insensible
chemical_list: D000485:Allergens; D007509:Irritants; D012967:Sodium Dodecyl Sulfate; D009532:Nickel