when we first met researcher monique williams, she'd wrapped up a study that found harmful metal particulates in the vapor from earlier models of e-cigarettes... following the evolution of the industry she's updating her study. >> so the original study we had looked at a cartomizer style e-cigarette and we had detected high amounts of tin, present in the cartomizer parts. >> are you still finding heavy metal particulate in the vapor? >> we are still finding that, yes. >> that's really scary because that's going into people's lungs. what happens to your lungs when those metal particles go into them? >> inhalation of metal, especially something like tin, can cause stenosis, and that could constrict the bronchioles and the airwaves in the lungs. >> across the hall at uc riverside they're studying one of those compounds. researcher iliana cordova is focused on nicotine concentrations in re-fillable e-cig liquids. in this case, the solution tested is "tennessee cured" by red oak, a fluid made by johnson creek enterprises, an online seller of e-liquids and accessories. >> we order a bunch of them a