Here is a new study that looked at urine samples from only smokers, only e-cig users, dual smokers, and never smokers: https://jamanetwork.com/journals/jamanet

Here is a new study that looked at urine samples from only smokers, only e-cig users, dual smokers, and never smokers: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2718096?widget=personalizedcontent&previousarticle=0 https://jamanetwork.com/journals/jamanetworkopen/fullarticle... If you look at Figure 1, the e-cig users and never smokers are pretty similar.