Instagram’s CEO disputed allegations by US prosecutors that his company hid negative information from the public while testifying during a blockbuster social media trial.

“I am not trying to encourage my team to hide anything,” the CEO, Adam Mosseri, told a California courtroom on Tuesday.

Mosseri is the first top executive from Meta, which owns both Instagram and Facebook, to testify in a historic lawsuit brought by 29 US states. His testimony began toward the end of the day on Tuesday and is slated to continue on Wednesday.

When the executive was posed with multiple questions about not disclosing low user numbers for Instagram’s features geared toward teen safety, he brushed them aside, saying: “We don’t publish every single stat.”

Jason Slothouber, a prosecutor for the state of Colorado, asked specifically about a tool called Take a Break, meant to encourage teens to close Instagram if they’d been scrolling for a while. Slothouber pointed out that just 1.8% of teens signed up for the feature, and that while Mosseri had touted the tool, he never publicly disclosed that number.

“I’ve definitely said publicly that the opt-in rates are low,” Mosseri responded. “I don’t know if I’ve said numbers.”

The jury trial, taking place in federal court in Oakland, California, began with opening statements last week. The lawsuit centers on the states’ allegations that Meta deliberately designed addictive products that hooked young people, leading to mental health issues, including anxiety, depression and suicide. The states additionally claim the social media company regularly collected data on children under the age of 13 without parental permission in violation of federal and state laws.

If found liable, Meta could be forced to pay damages as high as $200bn and change the design of its products to make them safer for kids. Legal experts say the outcome of this trial could fundamentally change the way social media apps function for young people.

Meta has denied all allegations, saying the states are chasing an “outlandish payout”. A spokesperson said Tuesday that Meta’s safety teams strive to be industry-leading and that Mosseri’s testimony showed the company does research to find ways to improve user experience.

Mosseri became the head of Instagram in 2018 and over the years has faced scrutiny about whether he may have dismissed internal warnings about the platform’s addictive design and negative effects on young people. He was called to testify before a Senate committee in December 2021 and as a witness in other trials about the alleged harm of social media to children.

On Tuesday, Slothouber asked Mosseri about a blog post he had published just one day before his Senate testimony. The post was titled “raising the standard for protecting teens and supporting parents online” and included the announcement of the Take a Break tool. Slothouber questioned Mosseri about the timing of his post.

“We had made progress, and we wanted to get the progress out, so we could talk about the progress,” Mosseri responded.

Slothouber then asked the CEO whether he was aware of the phrase “drumbeat messaging”, the idea of saying something repeatedly until it’s drummed into people’s heads. Mosseri said he had and that it’s necessary when dealing with parents and safety features. “We need to repeat it to raise awareness of those tools,” Mosseri testified.

Over the last week, jurors also heard from Arturo Béjar, a former Meta safety engineer turned whistleblower, who testified that the company has a “don’t ask, don’t tell” strategy when it comes to the safety of children on its platforms. They also heard from a psychologist and other former and current company employees.

The trial is expected to last through September with several other witnesses, including Meta CEO Mark Zuckerberg.