Irritant patch testing with sodium lauryl sulphate: interrelation between concentration and exposure time.
BACKGROUND
It is well known that the degree of skin reaction to an irritant depends on its concentration and exposure time.


OBJECTIVE
To determine the interrelationship between the concentration of sodium lauryl sulphate (SLS) and exposure time in both weak (subclinical) and severe reactions.


METHODS
Patch testing with SLS was performed at different concentrations (0.125%, 0.25%, 0.5%, 1.0% and 2.0%) and with different exposure times (3, 6, 12, 24 and 48 h). Evaluation was conducted by measurement of transepidermal water loss and by laser-Doppler flowmetry both 30 min and 24 h after patch removal.


RESULTS
We found more reliable and constant skin reactions 24 h after patch removal, and a higher correlation between SLS concentration and skin reaction.


CONCLUSIONS
We conclude that the concentration of SLS influences the test outcome to a larger degree than the exposure time. We present formulae by which the outcome of SLS patch testing at various SLS concentrations ranging from 0.125% to 2% and any exposure time between 3 and 24 h can be estimated.
Aramaki
J
J
Department of Dermatology, Nippon Medical School, Japan.
Löffler
C
C
Kawana
S
S
Effendy
I
I
Happle
R
R
Löffler
H
H
D000293:Adolescent; D000328:Adult; D017453:Dermatitis, Irritant / Q000175:diagnosis*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007509:Irritants / Q000008:administration & dosage; D017078:Laser-Doppler Flowmetry; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010328:Patch Tests / Q000379:methods*; D012967:Sodium Dodecyl Sulfate / Q000008:administration & dosage; D013501:Surface-Active Agents / Q000008:administration & dosage; D013997:Time Factors; D014870:Water Loss, Insensible / Q000187:drug effects
D007509:Irritants; D013501:Surface-Active Agents; D012967:Sodium Dodecyl Sulfate