INSECTICIDE-TREATED CLOTHING IS A PREVENTATIVE MEASURE FOR PESTS
Insecticide-treated clothing can reduce exposure to arthropods such as mosquitoes and ticks. These insects can leave people with itchy bites and potentially transmit pathogens that cause a variety of vector-borne diseases. Long sleeves and pants cover the skin and limit bites; however, insecticide treatment of clothing can provide extra protection due to the ability to repel and kill pests.
Permethrin is an example of an insecticide commonly used by commercial companies to treat clothing and other fabrics (tents, bednets) that are available to the public. This synthetic insecticide is in the pyrethroid class of insecticides and is similar to natural pyrethrum (found in chrysanthemums).
Some formulations of insecticide active ingredients (such as permethrin) used by commercial companies contain an additive to bind the active ingredient to the fabric. This extends the period of efficacy and limits the amount of unbound permethrin that contacts the skin. Only specific formulations are labeled for fabric (socks, pants, shirts, tents) application by spraying, dipping, polymer coating or microencapsulation.
FACTORY TREATED CLOTHING TO REPEL PESTS
While do-it-yourself insecticide treatment of clothing is possible for short-term use, it’s not recommended. Factory techniques such as dipping and microencapsulation provide an even distribution of the active ingredient, and extend the efficacy for the insecticide inevitably reduced due to washing, ultraviolet light exposure, heat and wear. The public can purchase new insecticide-treated clothing or mail in their own clothing and have it treated.
Only permethrin products labeled for treating clothing or other fabrics are used and the label instructions must be strictly followed. Insecticide-treated clothing is washed separately from other clothing, to limit the amount of insecticide that may be transferred to untreated items.
Scientists can adapt the World Health Organization Pesticides Evaluation Scheme for insecticide-treated bednets (arthropods such as mosquitoes and ticks exposed to swatches of clothing and knockdown/mortality observed) to evaluate the efficacy of permethrin-treated clothing over time.
SAFETY REGULATIONS FOR PERMETHRIN-TREATED CLOTHING
The Environmental Protection Agency (EPA) regulates the amount of permethrin used to treat clothing and evaluates potential routes of exposure (absorption, ingestion). Permethrin is the only active ingredient approved by the EPA for clothing treatment.
In 2006, the EPA conducted a human health risk assessment for permethrin, followed by an evaluation of permethrin-treated clothing in 2009 where the findings indicated permethrin-treated clothing was not a health risk. The 2009 assessment also evaluated adults, youth and toddlers wearing permethrin-treated clothing, as well as toddler mouthing activity on commercially treated clothing. In 2011, the EPA initiated a standard registration review of permethrin and this new review will be completed in 2017.
Brief (person on vacation/camping trip) or long-term (military or forestry personnel) use of permethrin-treated clothing is appropriate as this active ingredient is not efficiently absorbed through the skin.
As with any insecticide, if consumers treat their own clothing with the appropriate formulation of permethrin, label instructions should be followed. Permethrin should only be applied to clothing; hence, exposed skin should not be treated with permethrin. Skin should be treated with a repellent labeled for this type of use (e.g. DEET-containing products).
Permethrin-treated clothing can be a useful tool for reducing exposure to mosquitoes and ticks while people enjoy time outdoors.
Dr. Stephanie L. Richards is an Associate Professor of Health Education and Promotion in the Environmental Health Sciences program at East Carolina University. She received a B.S. in Biology and M.S. in Environmental Health from East Carolina University. She completed her Ph.D. in Entomology with a minor in geographic information science at North Carolina State University. She completed her post-doctoral work in Arbovirology at University of Florida, Florida Medical Entomology Laboratory.