I appreciate knowing. I want to be in the loop! Can you tell us which companies are selling the suspected harm and are not disclosing the harmful substance?
There are only two companies that regularly/consistently test & disclose the chemicals in their 'flavors'.
Flavourarts E-Cigarette line is tested to be diacetyl/similar diketones free...but not their Kitchen Magic line. Vendors of vaping flavors commonly sell from both lines - and do not indicate which is which. But both lines are clearly separate on the Flavourart site, so that's easy info to find.
TFA tests their flavors and discloses the results...giving descriptions like "trace amounts", "less than 1%", "less than .01%, etc. But apparently they don't regularly update this information into their product descriptions. However, the information can be found on their
Spec Sheets & Components List
The easiest way we've found to use the list is to click on the word "list" to the far right of a flavor that has both Acetyl Proprionyl & Acetoin (Butter is one). Then once it loads, you can click on either chemical on the Butter page, and it will give you a list of ALL their flavors containing that specific chemical.
The info below is more than you requested, but we'd like to get this all into one post so that we can link others to it easily
With TFA we need to keep in mind the current safety guidelines. "Trace amounts" and percentages that appear to be "wee tiny" typically exceed the safety guidelines substantially! The CDC/NIOSH safety guidelines can be found here:
CDC - NIOSH Update - Diacetyl and 2,3-pentanedione: NIOSH Seeks Comment On Draft Criteria Document Basically, the exposure limits for nasal inhalation are 8-25 ppb (parts per billion). Around 8ppb is for 8-hour exposure, and 25ppb is for short term/15 minute exposure. A flavor containing "less than .01%" used at even 5%, will exceed the guideline amounts.
Also to note - the recommendations above are for "normal breathing", not for putting a tube into our mouth and inhaling these chemicals (mixed with dozens/hundreds of others), directly into our lungs. If you haven't seen the report of a person developing popcorn lung from breathing in the 'steam' from microwave popcorn (no intense factory exposure required) - you'll likely want to check out the story here
http://www.nytimes.com/2007/09/05/us/05popcorn.html?_r=1&
Since these synthetic 'artificial butters' are GRAS for ingestion, and since they are used to create far more than just the 'creams & custards', here is an OSHA list (Table 1) of of the typical flavors where they are commonly used:
(you'll find they correspond with TFA's Component List)
This thread contains a LOT of great information
http://www.e-cigarette-forum.com/forum/diy-e-liquid/543911-acetyl-pyrazine-diacetyl-acetoine-help.html about FW's "claims" (and the crazy amount of these chemicals in one of their flavors), as well as links to an online "ppb calculator" that you can use to convert percentages to ppb.
It's all about making an INFORMED decision. For that, we need valid information & knowledge (on our part) and full, documented disclosure (on the vendor's part). At this point, the only two companies that are providing proof/evidence of anything are FA & TFA.