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

Kristin M Sullivan,Stephanie Richards,Thomas N Mather,Steven Meshnick,Maria Ospina,Avian White,John Ross,Charles B Beard,Antonia M Calafat,Sheana Funkhouser,Alison Poffley,Jo Anne Balanay,Megan Dyer,Jeffrey Driver

doi:10.1186/s13071-019-3314-1

Abstract

BackgroundVector-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.MethodsIn 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.ResultsThirteen 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.ConclusionsLLPI 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.

Highlights

Vector-borne diseases are an important cause of morbidity and mortality in the USA
One method of protection is the use of the insecticide permethrin on clothing which may come in contact with ticks and mosquitoes
We aimed to (i) evaluate the permethrin content that remained in Long-lasting permethrin-impregnated (LLPI) clothing after three months of routine use; (ii) determine the lethality of worn clothing to ticks and mosquitoes after three months of use; and (iii) determine the average absorbed dosage of permethrin among LLPI clothing wearers over a three-month period

Summary

Introduction

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, additional information is needed on the real-world effectiveness and safety of this preventative measure. Permethrin can be self-applied to clothing using aerosol spray This application method is effective but sub-optimal because it requires frequent reapplication and adherence is often poor [7, 8]. Factory-based, long-lasting perme thrin-impregnated (LLPI) clothing is EPA-registered [9] and has been shown to maintain repellency for up to 70 washes [10]. For this reason, LLPI clothing may be preferable among people with frequent, long-term potential exposure to ticks and mosquitoes. The duration of protection by LLPI clothing worn in real-world conditions is unknown

Objectives

Methods

Results

Discussion

Conclusion