As far as I know there have been no studies. And nicotine is not particularly addictive. With ecigs I think it's more the hit nicotine gives in your throat. But real cigarettes contain a chemical that makes nicotine more addictive.
There are two studies that show there is virtually no "2nd hand nicotine" in the vapor. And as another poster mentioned, that if there is no 2nd hand nicotine concerns from smoking, there sure won't be any from vaping. More people on ECF need to join CASAA and read the information available from their site. Especially the veteren vapers should be members and proponents of CASAA.