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MIAMI (CBSMiami) — More than 100 public health advocates are calling on Facebook to pull the plug on its new Messenger Kids app.

Facebook says it created the app to give children a safe way to video chat and send messages to their friends and family.

Tuesday, more than a dozen organizations and about 100 health experts sent a letter to Facebook CEO Mark Zuckerberg saying the new chat app, which is targeted at 6 to 12 year olds, will likely damage a child’s healthy development.

Isla Thomason, who is in kindergarten, has been using the Messenger Kids app since it was released in December.

“You could like do other stuff on your face, and it’s a really good app for kids,” she said.

Her father, Brett Thomason signed her up. Thomason, a technical coordinator at a charter school in Sarasota, likes that parent’s control who their children can talk to.

“That even creates a safer environment than traditional text messaging — that all you need is a phone number and you can send a message to anybody. There’s no blocks or anything with that,” Brett Thomason explained.

Messenger Kids has to be set up through a parent’s Facebook account because children under 13 still are not allowed to have one of their own.  The app, which was developed with help from child development experts, has no buttons for sharing, commenting or liking posts.

A Facebook spokesperson said in response, “We continue to be focused on making messenger kids be the best experience it can be for families.”

Josh Golin, Exective Director of the Campaign for a Commercial-Free Childhood is against the app.

“Really what it’s doing is indoctrinating much younger kids onto social media when their friendships should be offline and face to face,” he said.

Golin believes elementary school age children should not be exposed to the harmful effects of social media. He cites studies linking it to increases in depression, suicide rates, and body image issues.

“We wrote this letter because Facebook is the world’s largest social media company and by them going after young children and try to get them on social media, it’s going to be a game changer.”

Golin feels so strongly about keeping children off social media that he took the “wait until 8th” pledge, which encourages parents not to give their kids smart phones until the 8th grade.

The app analytics firm, App Annie, reports Messenger Kids has been downloaded about 80-thousand times on IOS since it launched on December 4.

Facebook says it has put in safeguards for cyberbullying, such as the ability to flag inappropriate content and block users. The app does not include ads.

However, even those steps are not enough to quell those experts’ fears.

“Even if these safeguards are effective, the app’s overall impact on families and society is likely to be negative, normalizing social media use among young children and creating peer pressure for kids to sign up for their first account,” the letter said.

A Facebook spokeswoman says the company has no plans to shut down the Messenger Kids app.

“Messenger Kids is a messaging app that helps parents and children to chat in a safer way, with parents always in control of their child’s contacts and interactions.”

Kristelle Lavallee, content strategist at the Center on Media and Child Health at Boston Children’s Hospital and a member of Facebook’s Advisory Committee, which helped develop Messenger Kids, said the letter highlights an “alarmist” perspective and shows a lack of understanding of the app.

“The whole idea of this tool is that parents are in control and can help scaffold their child’s learning,” said Lavallee. “Facebook needs to make sure it’s doing the due diligence of educating parents how to use Messenger Kids safely and effectively with their children.”

The letter does not acknowledge the parental controls Facebook put into place. Parents must set up a child’s Messenger Kids account and approve with whom they can communicate (parents must be friends on Facebook to do so).

Facebook said it plans to add more parental controls, such as a tool that could prevent kids from using the app during bedtime or while doing homework.

The company also said it is looking for new ways to educate parents about how to best use the app.

(©2018 CBS Broadcasting Inc. All Rights Reserved. Cable News Network, Inc., a Time Warner Company, contributed to this report.)