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MIAMI BEACH (CBSMiami) — Protesters gathered outside Miami Beach City hall for a second straight day – calling for officials to halt a spraying in the Zika fight.

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The group is opposed to aerial spraying of a controversial chemical called Naled – set to be sprayed Friday in Miami Beach.

“We are concerned that the Naled has more potential risk of creating the problem we are trying to avert than the actual concern with Zika,” said Brik Viera one of the protesters.

Opponents do not believe government assurances that the pesticide will not harm humans.

“It is a world where we can do our own research now. It really isn’t hard to look at toxicity reports,” said Irene Sperber.

She points to a study that showed children born in farming regions, where Naled is frequently sprayed on crops, have a higher rate of autism and learning disorders.

But at a forum hosted by University of Miami President Julio Frenk, himself a public health expert, a brain trust of doctors, epidemiologists and chemists concluded that health officials are moving wisely and safely to contain a dangerous virus.

“The best available evidence,” Frenk said.”suggests the aggressive attack against the spread of Zika is appropriate.”

Frenk said even more needs to be done, in the way of research and developing a vaccine.

“We seldom think of the cost of inaction,” Frenk said.

The spraying – originally set for Thursday – was pushed back until Friday after public outcry against it. City officials said the reason was to give residents time to leave if they are not comfortable.

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Miami Beach Mayor Philip Levine is not happy about the Naled spraying; however, he says, based on what the experts tell him, it must be done.

Related: Amid Concerns, Spraying Of Naled Delayed In Miami Beach’s Zika Fight

Levine said he learned from the state on Tuesday through a news release that Florida Governor Rick Scott was mandating the spraying of Naled on the beach using its helicopters and its contractors – a decision that Miami-Dade County Mayor Carlos Gimenez is also supporting.

The recommendations came after mosquitoes in Miami Beach tested positive for the Zika virus last week, prompting stepped up spraying efforts in the city’s transmission zone. Despite that, the mosquito population grew, raising more concern about the spread of the virus that has been linked to severe birth defects in children.

Opponents of the spraying remain unconvinced.

“I think the poisoning an entire population is unnecessary and wrong,” said a very pregnant Michelle Hurtado who stood on the side of 17th Street, outside Miami Beach City Hall chanting with other demonstrators.

Some plan to get out of town before Naled falls from the sky Friday morning.

“I am packing up my four-year-old daughter and we are driving home to Alabama, even though this is home, I have been here 17 years,” said Victoria Fickland.

As of Thursday, there were 56 non-travel related cases of the virus in Florida and 604 travel-related cases. About 84 pregnant women in the state have been infected with Zika.

So far, the local transmission zones are the following:

  • Wynwood Area – NW 22nd St. at the South, NE 2nd Ave to NE 23rd St. at the east; NW 3rd Ave to the west; and NE 36th St to the north.
  • Miami Beach Area – 28th Street to the north, 8th Street to the south, intercoastal water to the west and the Atlantic Ocean to the east.
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Click here for more information on the Zika virus or here for more Zika-related stories.