Permethrin exposure from wearing fabric-treated military uniforms in high heat conditions under varying wear-time scenarios

Abstract

This study examined the effect of high-temperature conditions and uniform wear time durations (expeditionary, 33 h continuous wear; garrison, 3 days, 8 h/day wear) on permethrin exposure, assessed by urinary permethrin biomarkers, from wearing post-tailored, factory-treated military uniforms. Four group study sessions took place over separate 11-day periods, involving 33 male Soldiers. Group 1 (n = 10) and Group 2 (n = 8) participants wore a study-issued permethrin-treated Army uniform under high heat environment (35 °C, 40% relative humidity (rh)) and expeditionary and garrison wear-time conditions, respectively. For comparison, Group 3 (n = 7) and Group 4 (n = 8) participants wore study-issued permethrin-treated uniforms in cooler ambient conditions under operational and garrison wear-time conditions, respectively. Urinary biomarkers of permethrin (3-phenoxybenzoic acid, and the sum of cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid) were significantly higher under high temperature compared to ambient conditions, regardless of wear-time situations (Group 1 vs. Group 3; Group 2 vs. Group 4; p < 0.001, for both). Under high-temperature conditions, expeditionary (continuous) compared to garrison wear-time resulted in significantly (p < 0.001) higher urinary biomarker concentrations (Group 1 vs. Group 2). Differences related to wear-time under the ambient conditions (Group 3 vs. Group 4) were not statistically significant. Findings suggest that wearing permethrin-treated clothing in heat conditions results in higher internal dose of permethrin above that observed under ambient conditions.

Keywords: Absorbed dose; Heat; Military; Permethrin; Pesticides; Urinary biomarkers.

Fig. 1

Study timeline. ǂCollection times are approximate, urine sample collected within hour from given time. ^&Demographic/health questionnaires and cognitive battery administered; physiological measurements recorded at first morning session. *First morning void. ^¶Groups 1 and 3 (operational/expeditionary: 33 h continuous wear): Group 1: in simulated hot environment (35 °C, 40% rh), Group 3: in comparison, ambient environment (average conditions 3 °C, 80% rh). ^¥Groups 2 and 4 (garrison: 3 day, 8 h/day wear) Group 2: in simulated hot environment (35 °C, 40% rh), Group 4: in comparison, ambient environment (average conditions 13 °C, 60% rh). Gray-shading: Time under study environmental conditions; urine (U) samples collected during time when study uniforms worn. Black: No study activities on Day 2 and 10

Fig. 2

a, b, c Median creatinine-adjusted permethrin metabolite concentrations.