but we now know that two very important politicians in washington believe the company has put profit over the mental health of teenage girls. james clayton, bbc news, san francisco. let's speak to a washington post reporter, thank you for coming on the programme. thank you for having me. how damaging do you think this testimony will be? it looks very bad for facebook, a lot of people throughout the hearing were comparing this to the big tobacco hearings of the 19905. the big tobacco hearings of the 1990s. there was a famous hearing and a 1994 when the ceos of seven tobacco companies testified before congress and said that they didn't believe their products were addictive, that nicotine was addictive. that then became infamous and contributed to really intense and damaging regulation against the tobacco industry. there are