Research Paper Title

Effect of Environmental Temperature and Humidity on Permethrin Biomarkers of Exposure in U.S. Soldiers Wearing Permethrin-Treated Uniforms.

Background

Environmental factors, including high temperature and humidity, can influence dermal absorption of chemicals.

Soldiers can be dermally exposed to permethrin while wearing permethrin-treated uniforms.

This study aimed at examining the effects of high temperature and a combined high temperature and humid environment on permethrin absorption compared with ambient conditions when wearing a permethrin-treated uniform.

Methods

Twenty-seven male enlisted soldiers wore study-issued permethrin-treated army uniforms for 33 consecutive hours in three different environments:

1. Simulated high temperature (35°C, 40% relative humidity [rh]) (n = 10);
2. Simulated high temperature and humidity (30°C, 70% rh) (n = 10); and
3. Ambient conditions (13°C, 60% rh) (n = 7).

Spot urine samples, collected at 21 scheduled time points before, during, and after wearing the study uniforms, were analysed for permethrin exposure biomarkers (3-phenoxybenzoic acid, cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid) and creatinine.

Biomarker concentrations were 60-90% higher in the heat and combined heat/humidity groups (P < 0.001-0.022) than the ambient group.

Also, the average daily permethrin dose, calculated 12 hours after removing the treated uniforms, was significantly higher in the heat (P = 0.01) and the heat/humidity (P = 0.03) groups than the ambient group.

Conclusions

There were no significant differences in biomarker concentrations or computed average daily dose between the heat and the heat/humidity groups.

Both hot and combined hot and humid environmental conditions significantly increased permethrin absorption in soldiers wearing permethrin-treated uniforms.

Reference

Maule, A.L., Heaton, K.J., Cadarette, B., Taylor, K.M., Guerriere, K.I., Haven, C.C., Scarpaci, M.M., Kenefick, R.W., Ospina, M., Calafat, A.M. & Proctor, S.P. (2020) Effect of Environmental Temperature and Humidity on Permethrin Biomarkers of Exposure in U.S. Soldiers Wearing Permethrin-Treated Uniforms. The American Journal of Tropical Medicine and Hygiene. 102(6), pp.1455-1462. doi: 10.4269/ajtmh.19-0543. Online ahead of print.