Repeated low-dose skin exposure is an effective sensitizing stimulus, a factor to be taken into account in predicting sensitization risk

• Published in: British journal of dermatology (1951) Vol. 162; no. 3; pp. 594 - 597
• Main Authors: Paramasivan, P., Lai, C., Pickard, C., Ardern-Jones, M., Healy, E., Friedmann, P.S.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.03.2010; Wiley-Blackwell
• Subjects: Adult; Analysis of Variance; Biological and medical sciences; contact dermatitis; Dermatitis, Allergic Contact - immunology; Dermatology; Dinitrochlorobenzene - administration & dosage; Dinitrochlorobenzene - toxicity; DNCB; Dose-Response Relationship, Drug; Female; Humans; Irritants - administration & dosage; Irritants - toxicity; Male; Medical sciences; Middle Aged; repeated exposure; Risk Assessment; Sensitising dose; Skin Tests; Young Adult; Skin disease; Contact dermatitis; Dermatology; Low dose; Risk factor; DNCB; Skin; Sensitization; Sensitising dose; repeated exposure
• ISSN: 0007-0963; 1365-2133
• DOI: 10.1111/j.1365-2133.2009.09489.x

Summary Background  Contact sensitization by ingredients in personal products is an important clinical problem. It is not clear how sensitization is induced by the generally low concentrations at which they occur but it might be the result of repeated exposure. Objectives  To compare the strength of contact sensitization induced by a single exposure to 2,4‐dinitrochlorobenzene (DNCB) (60 μg cm−2) or three repeated exposures to a subsensitizing dose (10 μg cm−2). Methods  Two groups (n = 10) of healthy adult volunteers were randomized to receive either a single patch of DNCB 60 μg cm−2 or three once‐weekly applications to the same site of 10 μg cm−2 DCNB. Four weeks after the last application, sensitization was quantified by measurement of responses (skinfold thickness) to a graded series of four challenge doses. Results  All the volunteers were sensitized and the strength of the responses was virtually identical between the groups. Conclusions  The same degree of sensitization was induced by three exposures to DNCB 10 μg cm−2 as by one exposure to 60 μg cm−2 of DNCB. Thus repeated exposure to low doses of contact sensitizers may increase the sensitizing potency. This must be taken into account in future risk assessments.