In Zika-Gripped Florida, Concerns Mount Over Insecticide Use - and Efficacy

The anti-Zika aerial insecticide spraying program is raising health concerns in Florida and beyond, and the high-rise landscape in Miami Beach may also make such campaigns ineffective.

Weeks ago, as mosquitoes carrying the disease became resistant to a less potent pesticide, Miami-Dade County turned to the more controversial naled. The Miami Herald noted that naled is "toxic not just to the noxious flying parasites, but also to beneficial insects like honey bees, as well as birds, some fish—and people."

The newspaper wrote:

Several studies suggest that long-term exposure to even low levels of naled can have serious health effects for children and infants as well as wildlife, including butterflies and bees, for whom exposure can be lethal. Some studies suggest it might have neurological and developmental effects on human fetuses, including on brain size, echoing the severe consequences that eradication of the Aedes aegypti mosquito that carries the Zika virus is meant to prevent.

"It's essentially a neurotoxin and can result in unborn children in particular having neurodevelopmental problems," Dr. Barry Ryan of Emory University told local station WTXL this week.

WTXL pointed out that the European Union has banned the insecticide.

Meanwhile, National Geographicreported on Friday that "the way those compounds are delivered doesn't fit the latest landscape where the insects are now flourishing--the high-rise hotels and luxury condos of Miami Beach."

Airplanes carrying the insecticides can't get sufficiently low to the ground, for one thing, and the tall buildings in Miami Beach create a sort of wind tunnel, as one expert told the magazine, complicating aerial spraying efforts.

"That makes it more likely that some bugs will be missed by spraying campaigns or get less than a full dose of killing pesticides, allowing them to become resistant," wrote journalist and author Maryn McKenna. "And that scenario could play out not just in Miami but also in the similar Gulf Coast cities where federal health authorities say the disease may land next."

However, the solution to that particular problem--working to ensure mosquitoes on the ground get a "full dose" of the insecticide--may be detrimental in the long run.

As Nichelle Harriott, science and regulatory director at Beyond Pesticides, told the Herald in mid-August: "Widespread application of naled is very troubling. We know it's highly neurotoxic. Studies show that low-dose exposures are problematic over a person's life."

"In cases such as this," she said, "they always say that people are just going to be exposed to small amounts for very short periods. But how long is it going to go on? How long are they going to be spraying? Those exposures do accumulate, and we need to look at those aggregate exposures."