MNDA VS DEET IN MOSQUITO REPELLENCY 287 Table II Comparative Level of Protection Afforded by 1% Repellent Versus Test Organisms Time of protection after application (hr) C. quinquefasciatus A. stephensi A. aegypti Level of protection (%) Deet MNDA Deet MNDA Deet MNDA 100 3 3 2 5 0 2 -90 3 4 2 5 1 2 -50 8 8 7 8 3 5 application. Although several explanations for diminished repellency are possible (i.e., penetration into the skin, repletion and/or adaptation by the mosquitoes), we believe low application rate (=25 l•g/cm 2) is the dominant reason. Indeed, Maibach eta/. (12) have reported that the minimum effective dose (MED) for Deet is approximately 16 l•g/cm 2. The decision to test 1% repellent in these studies was dictated by the limited toxicity data available to support exposing humans to higher concentrations of MNDA. Never- theless, the data summarized in Table II supports the efficacy of MNDA and provides impetus to complete the costly toxicity studies necessary to allow MNDA to be tested at levels comparative to that found in products containing Deet. CONCLUSION This pilot clinical study showed that 1% MNDA is significantly better than 1% Deet in terms of all measured parameters: fewer landings/probes, greater persistence, and a greater spectrum of repellency. ACKNOWLEDGMENTS The authors acknowledge the assistance of Dr. Ram Ramachandran in arranging the clinical study and of Mitchell Kotler for performing the statistical analysis. REFERENCES (1) N. R. Read, J. R. Rooker, and J.P. Gathman, Public perception of mosquito annoyance measured by a survey and simultaneous mosquito sampling, J. Am. Mosq. Control Assoc., 10, 79-87 (1994). (2) World Health Organization, http://www. ciesin. org/docs/001-613/001-613. html (2001). (3) M. Brown and H. A. Adelaide, Insect repellents: An overview, J. Am. Acad. Dermatol., 36, 243-249 (1997). (4) H. Qui, H. Won Jun, and J. W. McCall, Pharmacokinetics, formulation and safety of insect repellent N,N-diethyl-3-methylbenzamide (DEET): A review, J. Am. Mosq. Control Assoc., 14, 12-27 (1998). (5) T. G. Osimitz and R. H. Grothaus, The present safety assessment of DEET,J. Am. Mosq. Control Assoc., 11, 274-278 (1995). (6) R.J. Steltenkamp, R.L. Hamilton, R.A. Cooper, and C. Schal, Alkyl and aryl neoalkanamides: Highly effective insect repellents,J. Med. EntomoL, 29, 141-149 (1992). (7) K.M. Kinscherf, R.J. Steltenkamp, T.F. Connors, and C. Schal, Benefits of cleaning products

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