What active ingredient stays effective the longest?
DEET — in high concentrations (30% or higher) or when used in a controlled-release formula (which typically uses a 30%-35% concentration). DEET (Diethyl Toluamide) is a chemical. To some people, the thought applying it their skin makes them uneasy. Yet DEET has been in use since 1957 and has been repeatedly tested for toxicity. The Centers for Disease Control and Prevention (CDC) recommends its usage and considers it safe when applied according to label instructions. DEET is the only active repellent ingredient available currently in high concentrations in the U.S. Why? Only DEET’s higher concentrations have been screened extensively for toxicity (a lengthy and expensive process, costing millions). Such data is required by the Environmental Protection Agency, which regulates repellent ingredients in the U.S. Over time, newer repellents will likely be researched more extensively and higher concentrations will become available. In lower concentrations, active ingredients (DEET included)
