No, this is not directly related to vaping, but... Have a look at their press release here. Then consider the fact that they're doing this strictly via "guidance". No "Notice of Proposed Rulemaking" and normal regulatory process, just instant "fiat". What follows is an except from the actual guidance document:
These products are typically meant to be diluted before being consumed, and not consumed “as is.” An amount of highly concentrated liquid caffeine that would be safe for a given individual to consume in a properly diluted solution could nonetheless be unsafe for the same individual if the highly concentrated liquid were consumed directly. In the reasonably foreseeable scenario where a consumer makes an error diluting the product, or does not dilute it at all, that consumer could ingest a toxic quantity of caffeine.
Substitute one word, "nicotine" for "caffeine", and you've got a template for an instant ban on DIY nic base being sold to consumers. No notice, just done.
These products are typically meant to be diluted before being consumed, and not consumed “as is.” An amount of highly concentrated liquid caffeine that would be safe for a given individual to consume in a properly diluted solution could nonetheless be unsafe for the same individual if the highly concentrated liquid were consumed directly. In the reasonably foreseeable scenario where a consumer makes an error diluting the product, or does not dilute it at all, that consumer could ingest a toxic quantity of caffeine.
Substitute one word, "nicotine" for "caffeine", and you've got a template for an instant ban on DIY nic base being sold to consumers. No notice, just done.