Please be aware that only flavorings from a manufacturer with an FDA approval for food production should be used. Although we don't know the long-term safety implications of inhaling food flavorings, it must be safer than inhaling other types of flavorings such as those for perfumes, which ARE NOT approved for human consumption. Flavorings in a store in the food / cake / baking department probably comply with food regulations.
Perfumes and similar materials designed for skin product use are not approved for consumption and there is a possibility that such materials would not be safe to inhale. In addition, some materials that are safe to consume by eating ARE NOT safe to inhale.
You may prefer to use flavors available online that are approved and/or tested for consumption - and especially flavors from a Supplier who is a qualified chemist and fully understands the implications of correct specification FOR THE PURPOSE OF INHALATION.
For example, some materials MUST NOT be inhaled, and some materials
should not be inhaled. One substance that must not be inhaled is paraffin, whch is safe to eat in the USP/BP form, but when inhaled it is the primary cause of lipid pneumonia or 'oil pneumonia' (a type of pneumonia caused by inhaling mineral oils). Paraffin might conceivably be a component of skin products and perfumes. Castor oil is a vegetable equivalent that must not be inhaled.
A substance that should not be inhaled, or at least the amount should be minimised, is diacetyl - a flavoring used in 'buttery' flavors. Again, it is safe to ingest but not inhale.
As you can see, flavors therefore need to be both approved for human consumption (which in effect means from an original source with an FDA food production approval or equivalent), and also preferably sourced from an
e-liquid supplier who understands these issues and the important fact that some materials are safe to eat but should not be inhaled.
You should probably avoid sourcing materials from a skin products / perfume supplier, unless they can provide details of an FDA food production certificate. Many e-cigarette users consume over 3ml of refill liquid a day and in these quantities it is probably not safe to inhale anything and everything that smells nice.
