The number of Zika cases spread by mosquito bites in Florida has risen to 25, and with the number expected to rise further, airplanes have been flying over Miami spraying naled, a neurotoxic insecticide which kills adult mosquitoes. Some scientists are warning that naled may be more dangerous than the Zika virus itself.
What the Government Claims
The Environmental Protection Agency (EPA) may be playing down the risks associated with naled, claiming the tiny concentrations in the fine mist produced by spraying is strong enough to kill mosquitoes, yet it dissipates rapidly and little of it reaches the ground.
The EPA says on its website that when naled is properly applied, it can be used in mosquito control “without posing risks to people,” aside from potential short-term skin, eye, or nose irritation.
The agency acknowledges, however, that naled poses “risks to aquatic and terrestrial wildlife,” but says those “exist for only a short time.” It adds:
“Long term exposure from its use for mosquito control is unlikely.”
What Some Scientists Claim
Some scientists aren’t so optimistic about the safety of naled.
Long-term exposure to even low levels of the pesticide has been shown in several studies to have serious health effects for children and infants. Naled can be fatal to wildlife, such as bees and butterflies.
Some research suggests naled may have neurological and developmental effects on human fetuses, including smaller brain size – a frightening possibility, considering the Zika virus can cause the same condition, called microcephaly.
Trichlorfon, one of the main ingredients in naled, has also been linked to cancer. 
Nichelle Harriott, science and regulatory director at Beyond Pesticides, a Washington, D.C., organization, said:
“Widespread application of naled is very troubling. We know it’s highly neurotoxic. Studies show that low-dose exposures are problematic over the life of a person.
In cases such as this, they always say that people are just going to be exposed to small amounts for very short periods of time. 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.” 
Dr. David Perlmutter, a board-certified neurologist, said:
“I think we need to take a step back and recognize that we should always look at these interventions in terms of risk versus benefit. Sure there is a benefit here, but there is a risk.” 
A 2014 study by researchers at the University of California Davis (UC Davis) found that pregnant women living within a few miles of farms where pesticides like naled were sprayed had a 60% increased risk of their child developing autism.
A 2015 study by researchers at the University of California Berkeley showed that early exposure to organophosphates, the family of pesticides which naled is a member of, may be as harmful to children’s lungs as secondhand smoke.
Miami-Dade officials began applying naled after spraying a different class of pesticides, known as pyrethroids, failed to work fast enough.
Federal officials at the Centers for Disease Control (CDC) said the Zika-carrying mosquitoes are a challenge to locate and eliminate because they only need a tiny amount of water to breed in. There’s also a good chance the mosquitoes have become resistant to pyrethroids, a problem that is also affecting fleas, not to mention head lice that commonly infect children.
A Little More Cooperation Could Reduce Spraying
The best way to prevent mosquitoes from breeding is by simply getting rid of any standing water – even tiny puddles on the ground. Yet, few people seem to take that advice seriously.
Joseph Conlon, a spokesman for the American Mosquito Control Association, said:
“The most effective way to combat Zika is for people to get rid of their water containers. Unfortunately, you can’t get people to get rid of their water containers.”
Conlon said the group would prefer not to spray, and that they’d “rather just have people pick up their trash and get rid of their water.” 
 Miami Herald