There is reason to consider this a possibility, since many molecules may be potentially harmful when inhaled as vapor, with unknown health effects (ie vitamin E

There is reason to consider this a possibility, since many molecules may be potentially harmful when inhaled as vapor, with unknown health effects (ie vitamin E acetate), but under combustion would deteriorate mostly or entirely into the carbon forms that have well understood effect on health -- as a previous commenter mentioned, 10yr lifespan reduction from long term continuous cigarette use. There is just not longitudinal data available for vaporizing plants or synthetic nicotine/thc concentrates. It could be an even higher lifespan reduction than smoking!