Penetration of Anionic Surfactants into Skin II. Study of Mechanisms Which Impede the Penetration of Synthetic Anionic Surfactants into Skin11From the Research Laboratories of the Department of Dermatology of the Harvard Medical School at the Massachusetts General Hospital, Boston 14, Massachusetts.This investigation was supported by grants from the U. S. Army Chemical Corps (Contract DA 18-108-405-CML-672) and from the Division of Medical Sciences of the Department of Health, Education and Welfare, U. S. Public Health Service, National Institutes of Health (Grant RG-4760).We wish to thank Colgate-Palmolive Co., Lever Brothers Co., The Procter and Gamble Co., Monsanto Chemical Co., and California Research Corporation for the various surfactants used in this investigation. Mr. Roy W. Peet, Manager of the Association of American Soap and Glycerine Producers, Inc., helped us make contact with the surfactant manufacturers.