EFFECTS OF TOPICAL SKIN PROTECTANT ON HEAT-EXCHANGE IN HUMANS

Background: The application of a Topical Skin Protectant (TSP) under c hemical protective clothing may impair heat exchange and/or decrease t olerance time during exercise. Hypothesis: The extent to which TSP mig ht act as a barrier to heat transfer was unknown. Since TSP may be per meable to water vapor, we hypothesized that there would be no signific ant differences between treatments on variables effecting heat exchang e. Methods: There were 10 subjects who walked (3.5 mph, 3% grade) unti l volitional exhaustion in an environmental chamber (TA = 36.0 +/- 0.5 degrees C; TDP = 27.0 +/- 1.0 degrees C) in two conditions: no TSP ap plication (CON) and TSP application (TSP). TSP was applied to 21% of b ody surface area on six specific areas. Esophageal temperature, skin t emperature (8 sites), heart rate, and pre-and post-experimental weight s were measured. Mean skin temperature, mean body temperature, changes in esophageal temperature per min of exercise, evaporative heat loss, and sweating rate were calculated. Results: There was no effect (p < 0.05) of TSP on esophageal temperature, mean skin temperature, heart r ate, tolerance time (CON:139.3 +/- 32.5 vs. TSP:132.3 +/- 37.0 min), s weating rate (CON: 9.5 +/- 1.9 vs. TSP: 9.4 +/- 3.03 g.min(-1)) and ev aporative heat loss (CON:200.9 +/- 31.6 vs. TSP:215.9 +/- 25.9 W . m(- 2)). The change in TES per min of exercise averaged 0.014 +/- 0.003 de grees C during TSP and 0.012 +/- 0.003 degrees C during CON, and was h igher (p = 0.024) in TSP. At this rate, the difference between treatme nts for 4 h would be 0.48 degrees C. There were no adverse local or sy stemic reactions to TSP application. Conclusions: TSP application mini mally affected heat exchange under the conditions of this study.