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


Dermatitis. 2007;18(1):32-39. 

In This Article

Assignment of SAFs

SAFs serve to semiquantitatively represent sources of uncertainty associated with relating data obtained from a small number of individuals in a human study to a much larger consumer population that is using the test material in a particular type of product. The three SAFs applied represent uncertainties associated with interindividual variation (SAFi), vehicle matrix differences (SAFm), and qualitative differences in exposure (SAFe). Each of these SAFs are assigned a value of between 1 and 10, depending on the best judgment of the extent of the uncertainty associated with each. The scientific basis for these SAFs has been discussed elsewhere,[12]and the following values are considered appropriate for the current example:

  1. SAFi = 10 (standard)

  2. SAFm = 1 (minimal uncertainty; fabric conditioners are essentially aqueous solutions containing the ester quat as the main active ingredient, and the human study was performed with HEQ in distilled water)

  3. SAFe = 2 (limited uncertainty; the nature of exposure to HEQ through product use is considered unlikely to be more aggressive than that encountered in the human maximization test, which involves repeated exposure under occlusion to already irritated skin)

Calculation is as follows:


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