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Description of key information

Many studies are available investigating effects of the test substance on skin, including immuological and non-immuniological responses. Most studies are of limited quality and the test substance is used as a standard substance to elicit a skin reaction in humans. 
The test substance does induce skin effects in healthy adults and children after topical application.
An in vitro test (Wilhelm 2001) on cytotoxicity (NR uptake) with human keratinocytes showed an IC50 of 20 mmol. In the same study the test substance did not show any irritant properties to human skin (dose 20 mmol)

Additional information

The test substance induces skin reactions in adults and children after topical application (Rademaker 1988, Marriott 2005, Wray 1999). In healthy volunteers 1/12, 3/12 and 11/12 subjects showed positive reactions after topical application of the test substance at 4, 8 and 18 mM (effects at minimum on the cheek) (Larmi 1988).

A maximisation test with human subjects did not show any effects (Kligmann 1977).

In studies (Biosearch Inc 1991 and 1992) with 0.2% test substance in cosmetic products no effects were reported after single and repeated insult testing in human volunteers. Additional exposure of the application site to UV light did not lead to effects. In a study by Kligman (1990) erythema and some puritus was reported in 11 volunteers after challenge with 0.04% test substance (induction at 2%). In an additional study (McKenna 1994), 9/20 healthy volunteers (serving as a control group) showed positive skin reactions (erythema) after application of 5% test substance.

An in vitro test (Wilhelm 2001) on cytotoxicity (NR uptake) with human keratinocytes showed an IC50 of 20 mmol. In the same study the test substance did not show any irritant properties to human skin (dose 20 mmol)

No definite conclusion on the mechanism responsible for induction of skin reactions can be drawn. Both in persons with history of atopic eczema as well as in healthy (non-atopic) subjects, skin reactions were increased after application of the test substance (Lahti 1978).