Six people in the u.s. have died from vaping-related lung disease. the cdc, american medical association, and american lung association are warning people to now stop using e-cigarettes. tom, you're saying we still don't know what caused those six deaths exactly. >> reporter: no. that's part of the trouble here. we don't actually know what the link is. what we do know is that there's been this alarming rise both in incidents and awareness that there seems to be some kind of problem with people getting very sick, in some cases dying, after using e-cigarette devices. and that has really raised t...