title: Effects of different base agents on prediction of skin irritation by sodium lauryl sulfate using patch testing and repeated application test.
abstract: Animal testing for cosmetics was banned in the European Union (EU) in 2013; therefore, human tests to predict and ensure skin safety such as the patch test or usage test are now in demand in Japan as well as in the EU. In order to investigate the effects of different bases on the findings of tests to predict skin irritation, we performed patch testing (PT) and the repeated application test (RAT) using sodium lauryl sulfate (SLS), a well-known irritant, dissolved in 6 different base agents to examine the effects of these bases on skin irritation by SLS. The bases for PT were distilled water, 50% ethanol, 100% ethanol, a gel containing 50% ethanol, white petrolatum, and hydrophilic cream. The concentrations of SLS were 0.2% and 0.5%. Twelve different base combinations were applied to the normal back skin of 19 individuals for 24h. RAT was performed with distilled water, 50% ethanol, 100% ethanol, a gel containing 50% ethanol, white petrolatum, and hydrophilic cream containing SLS at concentrations of 0.2%, 2%, and 5%, being applied to the arms of the same PT subjects. The test preparation of each base was applied at the same site, with 0.2% SLS being used in the first week, 2% SLS in the following week, and 5% SLS in the final week. The results of PT revealed that skin irritation scores varied when SLS at the same concentration was dissolved in a different base. The results of RAT showed that although skin irritation appeared with every base at a concentration of 5%, the positive rate was approximately the same. In conclusion, our results suggest that skin irritation elicited in PT depends on the base, while in RAT, it does not depend on the type of base employed.
authors.affiliation: Research Laboratory, Ikedamohando Co., Ltd., Jinden, Kamiichi-machi, Nakaniikawa, Toyama 930-0394, Japan. Electronic address: horita.kt@ikedamohando.co.jp.
authors.forename: Kotomi
authors.initials: K
authors.lastname: Horita
authors.affiliation: Research Laboratory, Ikedamohando Co., Ltd., Jinden, Kamiichi-machi, Nakaniikawa, Toyama 930-0394, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Horita
authors.affiliation: Research Laboratory, Ikedamohando Co., Ltd., Jinden, Kamiichi-machi, Nakaniikawa, Toyama 930-0394, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tomita
authors.affiliation: Research Laboratory, Ikedamohando Co., Ltd., Jinden, Kamiichi-machi, Nakaniikawa, Toyama 930-0394, Japan.
authors.forename: Mitsue
authors.initials: M
authors.lastname: Yasoshima
authors.affiliation: Department of Allergology, Fujita Health University of Medicine, Otobashi, Nakagawa-ku, Nagoya, Aichi 454-8509, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Yagami
authors.affiliation: Department of Integrative Medical Science for Allergic Disease, Fujita Health University School of Medicine, Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan.
authors.forename: Kayoko
authors.initials: K
authors.lastname: Matsunaga
mesh_terms: D000328:Adult; D000368:Aged; D000431:Ethanol / Q000737:chemistry; D005260:Female; D006801:Humans; D007509:Irritants / Q000737:chemistry / Q000633:toxicity; D008297:Male; D008875:Middle Aged; D009823:Ointment Bases / Q000737:chemistry*; D010577:Petrolatum / Q000737:chemistry; D012882:Skin Tests; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry / Q000633:toxicity; D012997:Solvents / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry / Q000633:toxicity; D014867:Water / Q000737:chemistry; D055815:Young Adult
chemical_list: D007509:Irritants; D009823:Ointment Bases; D012997:Solvents; D013501:Surface-Active Agents; D014867:Water; D012967:Sodium Dodecyl Sulfate; D000431:Ethanol; D010577:Petrolatum
keywords: Effect of base; Patch testing; Repeated application test; SLS; Skin irritant