732 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Moreover, a premature confrontation in a judicial setting may create legal decisions adverse to the appropriate regulatory significance of such test systems as the Ames test. We in FDA recommend using mutagenic tests, including Ames-type tests, to evaluate products. These test systems have many advantages, and further experience with them may demonstrate direct regulatory utility. At present, some of the disadvantages, including the larger questions relating to society's policies about mutacarcinogens, should be addressed and resolved. REFERENCES (1) B. N. Ames, J. McCann and E. Yamasaki, Methods for detecting carcinogens and mutagens with the Salmonella/mammalian-microsome mutagenicity test, Mutat. Res., 31,347-364 (1975). (2) W. G. Flamm, Approaches to determining the mutagenic properties of chemicals: risk to future genera- tions, J. Environ. PathoL Toxicol., 1,301-352 (1977). (3) J. McCann, E. Choi, E. Yamasaki and B. N. Ames, Detection of carcinogens as mutagens in the Salmonella/microsome test: assay of 300 chemicals, Proc. Nat. Acad. Sci. USA, 72, 5135-5139 (1975). (4) J. McCann and B. N. Ames, Detection of carcinogens as mutagens in the Salmonella/microsome test: assay of 300 chemicals: discussion, Proc. Nat. Acad. Sci. USA, 73,950-954 (1976). (5) Federal Food, Drug, and Cosmetic Act As Amended, August 1972, Section 409(c)(3)(A), 21 U.S. Code 348.

J. Soc. Cosmet. Chem., 29, 733-741 (November 1978) Structure-function relationships of surfactants as antimicrobial agents JON J. KABARA Department of Biomechanics, Michigan State University, East Lansing, M148824. Received April 18, 1978. Presented at Annual Scientific Seminar, Society of Cosmetic Chemists, May 1978, Chicago, Illinois. Synopsis STRUCTURE-FUNCTION RELATIONSHIPS of various classes of SURFACTANTS as ANTIMI- CROBIAL AGENTS have been reviewed. It was concluded that while polar groups of the biocide tend to predict activity against a given genera, the chain length of the lipophilic group determines the most active member of the chemical class. In general, cationic surfactants are more active than anionic and nonionic agents. Optimum chain length for activity is between 10-! 6 carbon atoms. Gram (-) and yeast organisms are affected by the lower chain members while gram (+) organisms are affected by the longer chain surfactants. Nonionics, which in the past were considered not to have antimicrobial activity, were shown to be active when the mono-esters were formed from lauric acid. Because of this new property, nonionics, particularly monolaurin (Lauricidin?M), may be useful germicides in addition to their surface active properties. Their nontoxic and low irritation properties make them ideal candidates for cosmetic and toiletry formulations. INTRODUCTION Surface active agents are defined as substances which alter the energy relationships at interfaces. Compounds displaying surface activity are characterized by containing hy- drophilic (polar) and hydrophobic (hydrocarbon or nonpolar) groups. In our paper the term surfactant was chosen as descriptive of those compounds under discussion. Such terms as wetting agents, detergents or emulsifying agents should be reserved for surfactants denoting specific functions. Before 1930 the lack of success in the search for active antibacterial agents had slowly formed the philosophy that bacteria could never be expected to respond to chemo- therapy. The discovery of antimicrobial sulfonilamides, first observed by Trefouels in Fourneau's laboratory in France in 1935, gave impetus to test other classes of chemicals (1). The recognition and study of the germicidal action of certain surfactants stimulated widespread interest in the possible bactericidal potential of this class of chemicals. For early review of the subject, the reader is referred to Glassman (2). A recent edition of a 1958 treatise is also highly recommended even though the new text is without extensive revision (3). I will limit the scope of my discussion to include only 733