Interlaboratory studies with a proposed patch test design to evaluate the irritation potential of surfactants.
BACKGROUND
Development of cosmetic products and household detergents necessitates comparative study designs to assess the skin tolerance of products. In initial tests, the epicutaneous patch test for irritation is widely used.


OBJECTIVE
This study was conducted to develop a protocol that would facilitate a comparison of results obtained when tests are conducted by different laboratories.


METHODS
'In-house' and standardized patch test protocols were used to assess irritation potentials of surfactant-based products in intra- and interlaboratory studies using defined surfactant samples.


RESULTS
The various in-house protocols tested did not consistently produce equivalent results. In order to develop a study design that yields comparable results, various factors were identified and adjusted. The standardized study protocol includes occlusive application of 70 microl of the test substance to the back of 30 subjects, defined reading times and schemes, assessments based mainly on erythema, and inclusion of sodium laureth sulfate and sodium dodecyl sulfate as positive controls as well as water as a negative control.


CONCLUSIONS
Use of the standardized protocol and training of assessors improved the reliability and consistency of results whereby the irritation potentials of the references and test samples were ranked similarly by the laboratories.
Mehling
Annette
A
Cognis GmbH, Duesseldorf, Germany. Annette.Mehling@Cognis.com
Chkarnat
Catherine
C
Degwert
Joachim
J
Ennen
Joachim
J
Fink
Ernst
E
Matthies
Wolfgang
W
Roethlisberger
Rudolf
R
Rossow
Uwe
U
Schnitker
Jörg
J
Tronnier
Hagen
H
Wigger-Alberti
Walter
W
Wilhelm
Klaus-Peter
KP
D000328:Adult; D003358:Cosmetics / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007509:Irritants / Q000009:adverse effects; D007753:Laboratories; D008297:Male; D008875:Middle Aged; D010328:Patch Tests / Q000379:methods* / Q000592:standards*; D012867:Skin / Q000187:drug effects; D023422:Skin Irritancy Tests / Q000379:methods* / Q000592:standards*; D013501:Surface-Active Agents / Q000009:adverse effects*
D003358:Cosmetics; D007509:Irritants; D013501:Surface-Active Agents