740 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS acid are biologically active (15). The most active of these mono-esters is monolaurin (Lauricidin, 90% mono-ester), which is considered GRAS material. While the parent compound has useful but limited antimicrobial activity, monolaurin has been successfully compounded with other food-grade materials to yield products with wide spectrum activity and a short killing time (16). I'm sure other successful nontoxic formulations will be developed in the future. The other toxicological aspect of surfactants of particular concern to the cosmetic formulator is skin irritation (contact dermititis). Lipophilic chains (Cs and C•0) in satu- rated soaps are highly irritating while C • chain length is less irritating and C •4 to C •8 are the blandest. Thus, among soaps, short chains and high alkalinity are conducive to irritation. Commonly, long, straight chain surfactants are less irritating than short, branched chain products. Again, as with toxicity, the quaternaries are, in general, much more irritating than the anionics or nonionics. The nonquaternary amine salts tend to be at least as irritating as the quaternaries and possibly even more hazardous. In terms of eye irritation, the U.S. Food and Drug Administration laboratories have found a wide variation among individual surfactants and surfactant mixtures. As a general statement, the nonionics are least injurious, the cationics the most injurious and the anionics as intermediate. SUMMARY I have, thus, presented some structure-function associations which relate to cationic, artionic, amphoteric and nonionic surfactants as biocides. Of the large number of fatty acid surfactants used, the nonionics appear to be the most attractive. Based on their low index of toxicity and irritability and derived from renewable resources, nonionic surfactants offer real advantages to the cosmetic chemist. Contrary to the art for other nonionics, the high antimicrobial properties of the lauryl monoesters are unusual in that they can impart "medicated" or preservative quality to cosmetic formulations without added toxicity. With the current rage of "returning to nature," these fatty acid derivatives can rightly claim to be composed of "all natural ingredients." Current research indicates their use- fulness as food-grade preservatives, anticariogenic agents and in topical antimicrobial products (15, 16). As petro chemicals become less available and toxicology, rather than high germicidal property, becomes a greater consideration, I predict a wider and more diversified use for nonionic surfactants, particularly lauryl derivatives, as antimicrobial agents in foods, cosmetics and toiletry formulations. REFERENCES (1) F. Hawking andJ. S. Lawrence, "The Sulphonamides," Lewis Press, London, 1950. (2) H. N. Glassman, Surface-active agents and their application in bacteriology, Bact. Rev., 12, 105-148 (1949). (3) A.M. Schwartz, J. W. Perry and J. Berch, "Surface Active Agents and Detergents," R. E. Krieger Pub- lishing Company, Huntington, New York, 1977, pp 204-241. (4) J. Ferguson, The use of chemical potentials as indices of toxicology, Proc. Roy. Soc. (London), 127B, 387-404 (1939). (5) A.M. Schwartz et al., op cit., pp 230.

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