SALT LAKE CITY — Popular smartphone apps such as Snapchat and Instagram need to better help parents protect children from being exposed to sexually explicit content and sexual predators, digital watchdogs told a U.S. Senate panel Tuesday.

"We simply want transparency and additional information for parents," said Chris McKenna, founder and CEO of Protect Young Eyes, a nonprofit dedicated to helping parents and children create safe online environments.

"In no other context where we know that young people are spending a lot time do we allow for this much inaccuracy with the information we give parents to know how to protect their kids."

McKenna's comments came in response to Sen. Mike Lee's question about what app stores should be doing differently during a Senate Judiciary Committee hearing in Washington, D.C., titled, "Protecting Innocence in a Digital World."

The Utah Republican agreed with McKenna.

"Demanding or expecting that a child behave like a good internet citizen falls on deaf ears, especially when someone is encouraging a child to use an app that, at times, acts like a strip club," Lee said.

Panelists told senators that the risk of exploitation is increasing. Last year, the National Center for Missing and Exploited Children received more than 18 million reports of international and domestic online sexual abuse. Just four years ago, the number was closer to 4 million, said John Clark the center's president and CEO.

Research shows 45 percent of the nation's teenagers are online constantly and 44 percent are online several times a day, Lee said.

"This is a crisis affecting our children. It’s not an abstract one. It’s not a rare one," he said.

To their credit, Apple App and Google Play stores, use rating systems for their apps and have rules that prevent children from seeing harmful content, he said.

"And yet some of the most popular apps sold through those stores, including things like YouTube and Snapchat and Instagram, can and often do — in fact constantly do — provide sexually explicit content to children," Lee said. "And it’s not just when a child is looking for that. It’s happening when they input very innocent childlike search terms that have nothing to do with sexual content."

One of the problems is that Apple and Google use different rating systems to evaluate and score their apps, McKenna said.

McKenna called for a uniform, independent and accountable rating system along with more accurate and less generic descriptions of apps. He also contends that system defaults should be based on the age users provide to set up the device and the app so parents don't have to search for privacy and controls. He said it takes more than 30 steps to set up parental controls on a smartphone.

"What if the posture of our digital devices was one of protection and privacy instead of exploitation?" McKenna asked.

Sen. Richard Blumenthal, D-Conn., said parents have a primary responsibility, but need a more proactive and preventive role from big tech companies.

"I feel like we're drowning," said Melissa McKay, a South Jordan resident and mother of five children who attended the Senate hearing.

McKay suggests tech companies create a rating system for apps similar to those for movies and video games. It could remain self-rated but alert people to nudity, extreme violence or drug use, she said.

"This is not a censorship campaign. I don't want them to change any of the content at all. I'm just asking them to be transparent and to give parents better tools," said McKay, who works on proposed solutions with Protect Your Eyes.

As it is now, she said, the burden falls entirely on parents, who often aren't up on the latest and most popular apps.

"There so many things about Snapchat that parents don't understand," she said, citing features such as Snap Map and Discover.

The Church of Jesus Christ of Latter-day Saints also favors a rating system for apps similar to one for movies and entertainment software and uniform standards that are reviewed periodically as the apps change, said Marty Stephens, the church's director of government relations.

"We just believe that this is an area that is wide open for abuse, and there is easy access to children and to pornography on many of the applications that are used regularly by our youth," he said Tuesday. "We're not proposing that these be done away with or anything. We’re simply saying people ought to know what they’re getting into."

Church officials didn't testify at the Senate hearing, but might weigh in more formally in the future, according to Stephens.

"It's a real problem and we've got to figure out a good solution to protect our children," he said.

Sen. Marsha Blackburn, R-Tenn., said sexual predators no longer lurk in AOL chatrooms.

"They are right there on all of these apps that our precious children are using, whether it is Snapchat or Instagram or Facebook or YouTube or GroupMe," said Blackburn, who urged Snapchat in a letter Monday to take action to prevent children from being exposed to sexual predators and explicit content.

Angela Campbell, a Georgetown University law professor, told the committee that the problems parents have protecting the children's privacy, preventing exposure to inappropriate content and limiting their time on digital devices are the "direct" result of two things.

First, the business models of the dominant tech companies are designed to attract a large number of users, including children, and to keep them online as long as possible, so they can maximize revenue by collecting valuable data about the users and delivering targeted marketing to them, she said.

Second, government has failed to adopt sufficient protections for children and has not effectively enforced existing ones, Campbell said.

"In particular, the Federal Trade Commission’s failure to vigorously enforce the Children’s Online Privacy Protection Act creates an atmosphere in which the big tech companies — such as Google, YouTube, Facebook and Amazon — feel empowered to ignore existing safeguards," she said.

Judiciary Committee Chairman Lindsey Graham, R-S.C., tweeted after the hearing that he would work with Republicans and Democrats to "fashion a system that will require social media companies to use best business practices with appropriate government oversight" not only to protect children from sexual exploitation, but also to get social media companies to do better.