What's the deal with custard notes? Sorry if that's a dumb question.
There's no such thing as 'dumb question'! We2 (and many others) have been researching this issue for along time. We're throwing all this together quickly, so hopefully it'll be a good 'overview'
The three most commonly used "custard note" chemicals in vaping are diacetyl, acetyl proprionyl and acetoin. All of these chemicals (in their synthetic form, created for use in 'food flavors') are considered 'inhalation risk' chemicals by NIOSH/CDC. These are the chemicals that created the fumes/vapor in the popcorn factories that caused "popcorn lung" (bronchiolitis obliterans).
These chemicals also occur naturally in many plants, milk/dairy and fermentation. The concern appears to be with the synthetics used in food flavors as (to our knowledge) there has never been a case of bronchiolitis obliterans from inhaling the fumes/vapors of the non-synthetics.
These chemicals are prevalent in the food flavors we typically use for vaping/DIYing....and they are FDA GRAS for ingestion (but we're inhaling them, and that's a totally different issue). There are only two companies that test for these chemicals and publish the results (so that we can make an informed choice - whatever choice that may be). The E-Cig line of flavors from FA is totally 'custard note' free, and there are many flavors from TFA that are free of these chemicals as well (but some flavors still contain them). No problem there, because TFA reveals the test results on each of their flavors here:
Spec Sheets & Components
...and we can use the chemical CAS #'s below for searching the Component list (or click on the links at the end for specifif searches on each).
The CAS #'s are:
diacetyl: 431-03-8
acetyl propionyl: 600-14-6
acetoin: 513-86-0
Many erroneously think these chemicals are limited to "creams, butters, caramel & custards" - but the list of flavors below from TFA (with acetyl propionyl and/or acetoin) show the vast range of flavors that commonly contain them. We can assume these flavors from ANY vendor are going to contain these chemicals (unless they've tested for them and reveal the results of that testing publicly).
There's one more issue for considerations, and that's the "amount". The current NIOSH/CDC safety recommendations for inhalation exposure (normal breathing of room air, not direct inhhalation, like when we vape) is 8-25 ppb (parts per billion).
When we see these "trace amounts" (found on the TFA site) of say, .5% of a chemical in a flavor, we naturally/automatically think 'that's not much of a concern'. But if a flavor contains just .5% of one of the chemicals and it's used to make a juice at only 5%, the resulting juice contains 250,000 ppb. Of course, that 250,000 ppb juice will be 'vaporized' (heated, mixed with air in the tank, and then mix with air when we inhale), so the resulting exposure is NOT 250,000 ppb (it will be
much less)...but with a safety recommendation of only 8-25 ppb, many vapers feel that these 'trace amounts' are cause for concern.
As far as we2 are concerned, we're sticking primarily to FA and the TFA flavors that are 'clean'. Not only because of the health issues, but because we feel that EVERY manufacturer/vendor of flavors that profits/sells to vapers should test & fully disclose the chemical content of their flavors. This has been a known/public issue for MANY
years...and there's simply no excuse for the 'vape industry' to be acting anything like the 'tobacco industry' when it comes to hidden chemicals that are known inhalation risks. (There are vendors that know these chemicals are in their flavors and don't disclose it - and recently FW was caught cavors were 'diacetyl free', but were tested and found to contain high amounts
Of course, being old hippies, we also feel that everybody certainly has the right to make their own choices. We just want all vapers to have the chance to make an
informed choice!
(You'll need to go to the actual site and do the search, or click on the links below... and then click on the word "list" to the far right of each flavor to see the percentage/amount contained in each) - I was over the 1,000 character limit so I couldn't post the lists).
From TFA,
flavors containing acetyl propionyl
From TFA,
flavors containing acetoin: