The impact of exposure variables on the induction of skin sensitization.
Whereas many investigations of the variables associated with the elicitation of allergic contact dermatitis have been undertaken, to the point where we can begin to predict the likelihood of elicitation occurring in a given situation, the same is not true for the induction of skin sensitization. Studies have demonstrated that increasing dose has an impact; in an experimental setting, a number of variables received attention some decades ago. However, in the work reported here, the relative importance of the frequency and the duration of exposure is highlighted. In an investigation using a human repeated insult patch test, it was demonstrated that reduction of the exposure duration from 48 hr to 5 min decreased the rate of sensitization to 1% p-phenylenediamine (PPD) from 54% to 3%. However, in an extended clinical study, it was observed that infrequent but longer duration and higher concentration exposure to PPD was significantly less likely to induce sensitization compared to more frequent, short duration, and lower concentration exposure. Detailed statistical analysis of the results indicated that the most important factor driving the induction of skin sensitization was the number of exposures.
Basketter
David A
DA
Safety and Environmental Assurance Centre, Unilever Colworth, Sharnbrook, Bedfordshire MK44 1PR, UK. david.basketter@unilever.com
Jefferies
Donna
D
Safford
Bob J
BJ
Gilmour
Nicola J
NJ
Jowsey
Ian R
IR
McFadden
John
J
Chansinghakul
Wannisa
W
Duangdeeden
Imelda
I
Kullavanijaya
Preya
P
D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000008:administration & dosage; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010328:Patch Tests / Q000592:standards*; D010655:Phenylenediamines / Q000008:administration & dosage; D012016:Reference Values; D013997:Time Factors
D000485:Allergens; D010655:Phenylenediamines; C029728:4-phenylenediamine