IR3535

IR3535, named after its institutional code, is a synthetic insect repellent whose chemical designation is Ethyl butylacetylaminopropionate (often abbreviated as EBAAP). It was developed for use in consumer repellent products and has been marketed in various lotions, sprays, and wipes intended to deter mosquitoes, ticks, and other biting insects. In typical over‑the‑counter products, IR3535 is formulated at concentrations ranging roughly from 5% to 20%.

Chemical and formulations: The active ingredient is IR3535, usually combined with cosmetic carriers and solvents to improve skin spread and persistence. It is designed to be odorless or mild in fragrance compared with some older repellents, contributing to a favorable user experience in many products.

Mechanism and efficacy: IR3535 acts by interfering with host‑seeking behavior in insects, causing repellency rather than killing the insects. Its effectiveness depends on concentration, exposure duration, and the target species; protection duration can vary and is generally influenced by environmental conditions such as temperature and humidity. Some studies and product labeling indicate protection that is comparable to other repellents at similar concentrations for certain species, though results may differ by context.

Safety and regulatory status: In safety assessments, IR3535 has shown low acute toxicity and is often described as having a favorable irritation profile at typical use concentrations. It is approved for use in cosmetics and consumer repellents in several jurisdictions; in the United States and elsewhere, it appears in EPA‑registered products subject to label directions. Users are advised to apply as directed and avoid ingestion or contact with eyes.

See also: Insect repellent; DEET alternatives; Picaridin.