the necessary changes because they have put their astronomical profits before people. congressional action is needed. >> we have removed content that could lead to imminent real-world harm. >> reporter: facebook ceo mark zuckerberg responded to haugen's testimony in a post to his employees. posting in part, we care deeply about issues like safety, wellbeing, and mental health. many of the claims don't make any sense. if we wanted to ignore research, why would we create an industry leading research program to understand these important issues in the first place? facebook has also said it welcomes regulation but those who know the inner workings of the tech world say that won't save teens. >> because their business model is putting kids into these kinds of loops of engagement. and that's what i'm really worried about is that it's -- there isn't some quick fix to this thing. it's the intrinsic nature of the product. >> reporter: these two young women say, simply put, instagram endangered their very lives as teenagers. >> we shouldn't have to end up in hospital beds.