Evidence That Two Alkyl Ester Quaternary Ammonium Compounds Lack Substantial Human Skin-Sensitizing Potential

Ian R. Jowsey; Albert M. Kligman; Ian R. White; An Goossens; David A. Basketter

Disclosures

Dermatitis. 2007;18(1):32-39. 

In This Article

Methods

Human Maximization Testing

Human maximization testing was performed under the supervision of Dr. A.M. Kligman, of S.K.I.N. Incorporated (Conshohocken, PA). The local independent institutional review board gave ethical approval for the work. The protocol was based on that published previously.[10]For each test, 25 Caucasian women aged between 22 and 40 years were recruited after giving fully informed written consent. None had a history of skin disease, and they were not applying skin care treatments to their forearms. Disruption of the horny layer barrier was achieved by occluded exposure to a 1% solution (weight per volume [w/v]) of sodium lauryl sulfate (SLS) in a 25 mm Hill Top Chamber (Hill Top Research, Miamiville, OH) for 24 hours. In every individual, this resulted in a varying level of erythema and glazing of the skin surface. Transepidermal water loss in 5 randomly chosen subjects from each group was determined with an evaporimeter 3 hours after the Hill Top Chambers were removed. In each of these individuals, diffusional water loss had increased at least fivefold, indicating a loss of barrier function. For the induction phase, the test substance was applied 3 hours after the SLS chambers were removed. Each test material was applied under occlusion at a concentration of 15% (w/v) in distilled water (a high concentration of ester quat that is used in concentrated fabric softener formulations). Webril pads (Hill Top Research) within large Hill Top Chambers were saturated with the test item (200 µL) and applied to the SLS-treated site for five consecutive 48-hour exposures; with fresh material being applied to the same patch site for each exposure. Challenge was performed 10 to 14 days after the final induction patch was removed. The challenge patch was applied to a new forearm site at least 3 inches away from the induction site. The test material at a concentration of 15% (w/v) was again applied and was left for 48 hours under occlusion in 25 mm Hill Top Chambers. Patch sites were then assessed 2 hours and 2 days after the challenge patches were removed. For completeness, this challenge procedure was repeated on three volunteers after a further 7 days. Here, the challenge site was first pretreated with 10% SLS for 1 hour to increase skin permeability.

Diagnostic Patch Testing

Individuals attending St. John's Institute of Dermatology (London, UK) and the Contact Dermatitis Clinic at K.U. Leuven University Hospital (Leuven, Belgium) for evaluation of their dermatitis (not considered to be related specifically to exposure to fabric conditioner) were patch-tested as part of the normal clinical diagnostic process to evaluate possible contact allergy. A preliminary study was performed to identify appropriate concentrations for diagnostic patch testing. At a concentration of 2% (w/v), neither test substance was associated with irritant skin reactions whereas 5% (w/v) was identified as a concentration of test material on the irritant threshold. For the main study, each material was thus prepared at a concentration of 2% (w/v) and/or 5% (w/v) in petrolatum and was applied to patients' backs in 8 mm Finn Chambers (Epitest Ltd Oy, Tuusula, Finland) (approximate volume, 15 µL) under occlusion for 2 days. Patch sites were assessed immediately after patch removal and again after a further 2 days. Any reactions were scored according to the standard International Contact Dermatitis Research Group scale.[11]

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