identified a 13-year-old girl. they followed a few accounts associated with extreme dieting and eating. in a day, the apps were exclusively related to self-injury and eating disorders. cnn's clare sebastian has more on the combative hearing. >> reporter: in defensibly delinquent is how one senator described facebook. it faced intense and bipartisan focus on capitalism. not only instagram, but recently reporting in wall street journal suggests facebook knew about the risks from its own internal research and did not disclose or act on them. several senators describing this has facebook's tobacco moment. >> facebook has taken big tobacco's playbook. it has hidden its own research on addiction. >> instagram is that first childhood cigarette.