CNN Business  — 

A Facebook executive was grilled by Senators on Thursday about the impact its apps have on younger users, two weeks after an explosive report indicated the company was aware that Facebook-owned Instagram could have a “toxic” effect on teen girls.

The hearing, featuring Facebook’s global head of safety, Antigone Davis, is the first of two that the Senate Commerce Committee is holding on how Facebook approaches its younger users. Next week, the committee is expected to receive testimony from a Facebook whistleblower.

“We now know that Facebook routinely puts profits ahead of kids’ online safety. We know it chooses the growth of its products over the well-being of our children,” Democratic Sen. Richard Blumenthal said in opening remarks at the hearing. “And we now know it is indefensibly delinquent in acting to protect them.”

“The question that haunts me,” Blumenthal added, “is how can we, or parents, or anyone, trust Facebook?”

In a sign of the bipartisan pressure on this issue, Republican Sen. Marsha Blackburn echoed Blumenthal in her opening remarks directed at Facebook. “We do not trust you with influencing our children,” she said.

The Wall Street Journal reported earlier this month that researchers at Facebook have been conducting studies for the past three years into how Instagram, which it owns, affects its millions of young users. The research shows the platform can damage mental health and body image, especially among teenaged girls.

Blumenthal said his office created an Instagram account identifying as a 13-year-old girl. It followed some easily discoverable accounts associated with extreme dieting and eating disorders. Within a day, he said, the Instagram recommendations were “exclusively filled” with other accounts that promoted self harm and eating disorders. (Davis said those accounts would be in violation of Instagram’s policies that crack down on content promoting self-harm.)

Following the Journal report, Instagram said it was looking at new ways to discourage users from focusing on their physical appearance. The company also said that while Instagram can be a place where people have “negative experiences,” the app also gives a voice to marginalized people and helps friends and family stay connected.

“What’s been lost in this report is that in fact with this research, we’ve found that more teen girls actually find Instagram helpful – teen girls who are suffering from these issues find Instagram helpful than not,” Davis said Thursday. “Now that doesn’t mean that the ones that aren’t, aren’t important to us. In fact, that’s why we do this research.”

Davis, who identified herself as a mother and former teacher, also pushed back on the idea that the report was a “bombshell” and did not commit to releasing a full research report, noting potential “privacy considerations.” She said Facebook is “looking for ways to release more research.”

The report, and the renewed pressure from lawmakers in its aftermath, also appeared to force Instagram to rethink its plans to introduce a version of its service for kids under 13. Days before the hearing this week, Instagram said it would press pause on the project.

“While we stand by the need to develop this experience, we’ve decided to pause this project,” Adam Mosseri, head of Instagram, wrote in a blog post published Monday. “This will give us time to work with parents, experts, policymakers and regulators, to listen to their concerns, and to demonstrate the value and importance of this project for younger teens online today.”

In the blog post Monday, Mosseri acknowledged that the Journal’s reporting “has raised a lot of questions for people.” Those questions may only persist after the hearing.

“For 2.5 hours, Ms. Davis offered evasions and misdirections, but refused to commit to a single substantive change or even greater transparency,” Josh Golin, executive director at Fairplay, a child advocacy group formerly known as the Campaign for a Commercial-Free Childhood, said in a statement Thursday. “She also continued to push the fiction that Facebook’s interest in Instagram Kids is driven by concern for children’s safety when the company’s own leaked documents make clear it’s part of a larger strategy for growth and to compete with TikTok and Snap for young users.”

CNN’s Donie O’Sullivan contributed to this report.