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Parasit Vectors. 2019 Jan 23;12(1):52. doi: 10.1186/s13071-019-3314-1.

Bioabsorption and effectiveness of long-lasting permethrin-treated uniforms over three months among North Carolina outdoor workers.

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Department of Epidemiology, University of North Carolina Gillings School of Global Public Health, Chapel Hill, NC, USA.
Risksciences LLC, Longboat Key, FL and University of South Florida, College of Public Health, Tampa, FL, USA.
Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.
Division of Vector-borne Diseases, Centers for Disease Control and Prevention, Ft. Collins, CO, USA.
Environmental Health Sciences Program, Department of Health Education and Promotion, East Carolina University, Greenville, NC, USA.
Center for Vector-Borne Disease, University of Rhode Island, Kingston, RI, USA.
Department of Epidemiology, University of North Carolina Gillings School of Global Public Health, Chapel Hill, NC, USA.



Vector-borne diseases are an important cause of morbidity and mortality in the USA. Effective, convenient prevention methods are needed. Long-lasting permethrin-impregnated (LLPI) clothing can prevent tick bites, however, additional information is needed on the real-world effectiveness and safety of this preventative measure.


In this pilot study, we recruited state and county park employees from North Carolina to wear LLPI uniforms for three months during the summer of 2016. We collected spot urine samples for biomonitoring of permethrin metabolites at one week, one month and three months after first use of the LLPI uniform. Following three months of wear, we collected pants and socks and analyzed them for permethrin content and mortality to ticks and mosquitoes.


Thirteen park employees were included in the analysis. Bioactive amounts of permethrin remained in all clothing swatches tested, although there was great variability. Tick mortality was high, with 78% of pant and 88% of sock swatches having mean knockdown percentages ≥ 85%. In contrast, mosquito mortality was low. Over the study period, the absorbed dosage of permethrin averaged < 4 μg/kg/d of body weight based on measurements of three metabolites.


LLPI clothing retained permethrin and bioactivity against ticks after three months of use in real-world conditions. The estimated absorbed dosage of permethrin was well below the U.S. EPA level of concern, suggesting that LLPI clothing can be used safely by outdoor workers for tick bite prevention.


Mosquitoes; Permethrin; Permethrin absorption; Permethrin treatment; Repellent; Tick bites; Ticks

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