We have this Popular Science article on the need to 'regulate' e-cigarettes, whatever that entails. I smell vested interest involved in this article. In fact the reek of it is palpable!

 http://www.popsci.com/article/science/e-cigarettes-not-harmless-should-be-regulated-cigs-study-says?src=SOC&dom=fb

Looking at the abstracts for the two studies Popsci cited as indicating second-hand vapor being possibly harmful. The inline citations in the article link to abstracts only for both studies which is a concern, in and of itself. You must pay a fee to see who funded the study and the methodologies. Even though any regulation put in force would affect ALL of us, only some of us will have access to the studies due to fees. This raises an important question. Should studies that are used to determine public policy NOT be available to that SAME public free of charge?

There are other problems with these studies being cited. The first study they used does not accurately reflect the main statement of the paragraph, that second-hand vapor may also be harmful, in the abstract alone. Financial associations were not indicated in either abstract.

If all of the issues concerning secondary-vapor is not properly peer-reviewed or scrutinized by objective non-vested parties then... I don't know what... We base policy and laws on incomplete science! If secondary vapor is revealed to be harmless to present non-smokers by diligent, competent, rigorous and objectively applied scientific method, then that would be the basis for the well justified and vociferous demand by a proactive public to its lawmakers:

"Inform and educate, but DO NOT LEGISLATE!"

ETA: Other than requiring placement of concise and well researched, life-saving info on the containers, of course...