US legislators condemned Facebook on Tuesday, accusing the social media giant of sowing division, harming children and fuelling ethnic violence in its insatiable quest for ever-bigger profits.
The blistering criticism of Facebook and its chief executive Mark Zuckerberg came during an extraordinary day of Congressional testimony from Frances Haugen, a former employee who has come forward as a whistleblower on practices and policies inside the company.
Ms Haugen said Facebook algorithms rewarded posts with high levels of user engagement, often resulting in the platform pushing harmful content to users.
If Facebook had better regulation, "they would get rid of engagement-based ranking because it is causing teenagers to be exposed to more anorexia content, it is pulling families apart, and in places like Ethiopia it's literally fanning ethnic violence", she said.
Ms Haugen, 37, a data scientist from Iowa, told a Senate commerce subcommittee hearing that Facebook hides its algorithms and is also responsible for fuelling hate speech across its platform.
This "dangerous online talk has led to actual violence that harms and even kills people", she said, noting that Facebook is "accountable to no one".
In her testimony, she told of the danger of the power in the hands of a service that is woven into the daily lives of so many people.
"It is about Facebook choosing to grow at all costs, becoming an almost trillion-dollar company, by buying its profits with our safety."
Ms Haugen has provided Facebook documents to Congress and The Wall Street Journal, which reported the company contributed to increased polarisation online when it made changes to its content algorithm, failed to take steps to reduce vaccine hesitancy, and was aware that Instagram harmed the mental health of teenage girls.
She called for transparency about how Facebook entices users to extend their stay on the site, giving them ample opportunity to advertise to them.
"As long as Facebook is operating in the shadows, hiding its research from public scrutiny, it is unaccountable," Ms Haugen said. "They need to take responsibility."
Panel chair Senator Richard Blumenthal, a Democrat, said Facebook knew its products were addictive.
"Tech now faces that Big Tobacco, jaw-dropping moment of truth," Mr Blumenthal said.
He called for Mr Zuckerberg to testify before the committee, and for the Securities and Exchange Commission and Federal Trade Commission to investigate the company.
"Our children are the ones who are victims. Teens today looking in the mirror feel doubt and insecurity. Mark Zuckerberg ought to be looking at himself in the mirror," Mr Blumenthal said.
Senator Edward Markey, speaking to the absent Mr Zuckerberg, said during the hearing: "Your time of invading our privacy, and preying on children is over. Congress will be taking action."
"I don't know why it went down, but I know that for more than five hours Facebook wasn't used to deepen divides, destabilise democracies and make young girls and women feel bad about their bodies," Ms Haugen said.
She said those in charge of the social media giant knew how to make Facebook and Instagram safer but they instead put "their astronomical profits" ahead of people.
The revelations have sparked a storm in Washington as legislators accuse Facebook of covering up research about the company's platforms' negative effects, including how it helped to fan the flames of violence that led up to the January 6 insurrection at the US Capitol.
Ms Haugen said Facebook used mostly artificial intelligence to search for hate speech and that only 20 per cent is filtered through humans, making it a very popular device for alt-right extremists.
"We can have social media we enjoy that connects us without tearing our democracy apart our democracy, putting our children in danger, and sowing ethnic violence around the world," she said.
"The way we'll have reconciliation and before we can move forward is by first being honest and declaring moral bankruptcy."
At a hearing last week, US legislators questioned Facebook global head of public safety Antigone Davis over documents that show Instagram can worsen the mental health of teens who are already struggling.
Facebook maintains that Ms Haugen’s allegations are misleading and insists there is no evidence to support the premise it is the primary cause of social polarisation.
Facebook said Ms Haugen had worked at the company for less than two years and had not been privy to executive decision making.
"We don't agree with her characterisation of the many issues she testified about. Despite all this, we agree on one thing: it's time to begin to create standard rules for the internet," Facebook said.