Mosquito spraying has been stalled in Zika-plagued Florida amid fears about toxins in the repellent.

Scores of people in gas masks staged a protest outside the town hall in Miami this week, forcing officials to postpone Thursday’s spraying until Friday – at the earliest. 

The protesters claim naled could pave the way to another heap of illnesses aside from Zika – and some insist they already feel the affects.

It leaves the region in an uncomfortable position as lawmakers attempt to wipe out the seemingly multiplying population of Zika-infected mosquitoes. 

But the question is: do the protesters have a point?  

The protesters outside Miami’s town hall (pictured on Wednesday) claimed naled could pave the way to other illnesses aside from Zika – and some insist they already feel the affects

‘My tongue for four hours felt so tight, and shaky, I was about to go to the emergency room,’ one woman told CBS outside the town hall on Wednesday.  

Indeed, environmental activists and some scientists say naled damages the nervous system and respiratory tract, and might be linked to leukemia in children.

It was banned in the European Union in 2012 because of its potential risk for human health and the environment.

But Miami-Dade County is using it with the blessing of the US Centers for Disease Control and Prevention and the Environmental Protection Agency. 

They say it is safe when used in small doses.

But ‘if it’s not safe to use in Europe, why is it safe to use in Miami?’ asks Michelle Harriott, science and regulatory director of a Washington-based NGO called Beyond Pesticides.

Miami-Dade County Mayor Carlos Gimenez addressed the crowds on Wednesday with a nurse, Dr Christine Curry, who has treated microcephaly, to emphasize the importance of blitzing Zika however possible. 

‘Zika is real, and while we don’t understand it fully that is not a reason to dismiss its impact,’ Dr Curry said.

Mayor Gimenez added: ‘I have to be consistent in application of spraying.

‘We cannot just pick and choose where to spray, there’s a science.’

CDC director Tom Frieden has said that naled, which has been used in the United States since 1959 to combat mosquitos, is not harmful at the low concentrations in which it is used in America.

The EPA website says ‘people aren’t likely to breathe or touch anything that has enough insecticide on it to harm them. Direct exposure to naled during or immediately after application should not occur.’

But it also cautions people sensitive to chemical products to stay inside with the windows closed during fumigation with naled.

Harriott said, ‘They use small doses at a time, but over several months that adds up. It depends on how long it will be sprayed. It could be for the rest of the year. If that is the case, we should be concerned about that.’

In experiments with animals, exposure to naled at high concentrations has been shown to cause nausea, weakness, paralysis, convulsions and other problems including respiratory failure and even death, said Elvia Melendez Ackerman, a professor of environmental science at the University of Puerto Rico.

Naled breaks down into something called dichlorvos, which in 1991 the World Health Organization labeled as a possible carcinogen for humans.

Naled not only kills mosquitoes but is also toxic for bees, butterflies, fish and other aquatic species.

Melendez was active in the fight against using naled in Puerto Rico. Fumigations with it were halted in July on orders from Governor Alejandro Garcia Padilla.

Now the US territory is being sprayed with an organic product that kills mosquito larvae.  

No vaccine or treatment has been approved for Zika.

The virus, first detected in Brazil last year, has rapidly spread across the Americas and parts of Asia.

In recent weeks, U.S. authorities determined that local mosquitoes were transmitting Zika in an area of south Florida. The U.S. territory of Puerto Rico has also experienced a widespread outbreak.

U.S. health regulators cleared the way last month for a trial in Key Haven, Florida to assess the effectiveness of Intrexon’s GM mosquitoes to reduce levels of the aedes aegypti mosquito population, which is known to carry Zika, dengue and chikungunya.

There is vote scheduled in November seeking community approval for the trial, as the use of Intrexon’s mosquitoes have raised concerns among the locals about its safety.

Naled not only kills mosquitoes but is also toxic for bees, butterflies, fish and aquatic species

In the letter, the politicians said that delaying Florida’s access to Intrexon’s technology posed ‘an unnecessary health risk’ to the people of Florida, the company said.

The mosquitoes are genetically altered so their offspring die before they can reproduce.

Trials in Brazil, Panama and the Cayman Islands have shown that the GM mosquitoes can reduce localized Aedes aegypti populations by more than 90 percent.

The GM mosquito strain is made by Oxitec, an Oxford University spin-off company that is now a UK subsidiary of U.S.-based Intrexon.

While most people experience mild symptoms, Zika infections in pregnant women have been shown to cause microcephaly, a severe birth defect in which the head and brain are undersized. 

In adults, it can cause a rare neurological syndrome called Guillain-Barre.



The Zika (ZEE’-ka) virus was first discovered in monkey in Uganda in 1947 – its name comes from the Zika forest where it was first discovered.  



It is typically transmitted through bites from the Aedes species of mosquitoes.

They are aggressive feeders, commonly biting multiple people in quick succession, fueling the spread of the virus.   

They are most active during mid-morning and then again between late afternoon and nightfall.


Scientists have found Zika can be transmitted sexually – from both men and women.  

Couples should abstain or wear condoms for eight weeks if either partner has traveled to a country with a Zika outbreak, regardless of whether they have symptoms. 


A mother can pass the virus to her unborn baby during pregnancy. 

There are two ways this can happen: through the placenta, and through the amniotic sac.

Since the virus can live in the womb lining, there is a chance the baby can become infected during birth.


The majority of people infected with Zika virus will not experience symptoms. 

Those that do, usually develop mild symptoms – fever, rash, joint pain, and red eyes – for no more than a week.

There is no specific treatment for the virus and there is currently no vaccine.


Individuals can protect themselves from mosquito bites by using insect repellents.

They could also wear long sleeves and long pants – especially during daylight, when the mosquitoes tend to be most active, health officials say.

Eliminating breeding spots and controlling mosquito populations can help prevent the spread of the virus.