Fact
E-cigarette aerosol has up to 100 times more nickel, a toxic metal, than cigarette smoke.
Source 1:
Williams, M., Villarreal, A., Bozhilov, K., Lin, S., & Talbot, P. (2013). Metal and Silicate Particles Including Nanoparticles Are Present in Electronic Cigarette Cartomizer Fluid and Aerosol. Plos ONE, 8(3).