Naled, an insecticide to control Zika virus, is worrying residents of Florida’s Miami-Dade County. According to an article in the L.A. Times, the insecticide is sprayed to kill adult mosquitoes on contact by inhibiting an enzyme called acetylcholinesterase, also found in humans. University of Guelph emeritus professor Keith Solomon, School of Environmental Sciences, told the Times that everything can be toxic — it’s the dose that makes the poison. The U.S. Environmental Protection Agency and Centers for Disease Control say that spraying is done in “ultra-low volumes,” which Solomon said are unlikely to harm people. The European Union has banned naled. Solomon said that, if Zika made it to Europe, the EU might consider lifting the ban on aerial application.