I see where you are coming from, peppermint oil has been used for many years for medicinal purposes and normally i would say go for it,
How ever after reading.
http://www.vaportalk.com/forum/forum/forum/topic/11440-gateshead-doctor-calls-for-research-into-e-cigarettes/page__p__103214__fromsearch__1#entry103214
Sorry have forgotten how to do links, It has put me right off oil based liquids.
Do you have any double mint gum or creme de menthe left? you could mix it with or a food grade peppermint flavoring try adding a bit of that to it in a smaller bottle