There is a considered statement from WHO on their current position here -
WHO - Marketers of electronic cigarettes should halt unproved therapy claims - *E-Cigtest, the ultimate electronic cigarettes review site and forum* Le site de la cigarette électronique
Their definition is - nicotine delivery system and health product.
These points seem particularly important to me:
... products including the electronic cigarette cannot be supported unless they meet national regulatory criteria for efficacy, safety and quality of a new public health product.
... scientifically rigorous, peer-reviewed studies to substantiate claims for the electronic cigarette as an effective smoking cessation aid. In this respect, WHO does not equate a manufacturers undocumented claims of safety or toxicity to peer-review by a science based committee.
... the generation of theoretically adequate safety data by one manufacture is not tantamount to validation of all electronic nicotine delivery devices.
... WHO is not aware of any set of data that establishes the safety of nicotine and/or propylene glycol (in addition to other constituents of the product which are present to confer the claimed cigarette mimicking sensory characteristics) when heated and delivered to the lung. WHO is not convinced of the precise nature and amount of the constituents of the emissions.
... WHO is concerned about the variety and lack of uniformity of these products. [I wonder what the significance of that statement is]
... WHO does not discount the possibility that the electronic cigarette could eventually be regarded as a useful smoking cessation aid. That said, rigorous pharmacokinetic studies, safety and efficacy trials, and review and approval by national authorities which regulate NRTs must be conducted.
... the burden is on product sponsors to satisfy regulatory agencies and to ensure public health institutions that their products are safe (and effective if such claims are made) - not on WHO or regulatory agencies to prove all aspects of potential harm when there is a plausible basis for harm.
... substantiation of smoking cessation and other health claims would include rigorous pharmacokinetic studies, safety and efficacy trials, and review and approval by major drug regulatory authorities of the following types data and studies: (1) the complete listing of ingredients in electronic cigarettes, (2) the effect on smoking cessation of these products compared to NRT and placebo, and (3) adverse effects caused by these products.
... WHO urges its Member States to require manufacturers to provide adequate scientific data in accordance to the criteria set by national regulatory bodies.
... WHO TobReg also recommends that claims for safety relative to cigarettes, health benefits, or claims such as effectiveness as smoking cessation aids or as cigarette substitutes be prohibited until such claims are substantiated with data accepted by scientific organizations and approved by regulatory agencies.
... WHO TobReg strongly recommended that these class of products not be exempted from clean air laws that restriction restrict cigarette smoke exposure (see WHO FCTC, Article 8) until adequate evidence is provided to assure the regulatory authority that use of the product will not expose people to toxic emissions. [How would this effect us? Will we be unable to vape in no smoking areas?]
... Research is needed on the delivery and absorption of nicotine in relation to these devices, both acutely and chronically, in order for regulators to establish the dosage and formulation for regulatory approval.
... This class of products should be regulated as nicotine delivery systems and must meet the scientific, efficacy and safety criteria established by regulatory authorities prior to sale and marketing.