That is 1/4 of 1% in a 10ml bottle of juice. So the flavor is already diluted.
So that would be 0.0025 p/ml (?)... I should have paid attention in math. I'll ask my daughter when she gets home - she's smart.
As a point of reference 0.0025=25ppm(parts-per million). I think everything has risk in life, but if the number Bruce got was accurate, I don't think that it would cause any harm.
I know this thread has been dormant for a couple months, but people might wind up here as they research diacetyl, and this requires correction:
1/4 of 1% does reduce down to 0.0025, but it's still a dimensionless quantity and doesn't relate in any way to a "per ml" standard. We're talking percentages in a solution. No matter what the quantity, it's always going to be 1/4 of 1% (or 0.25% or 0.0025, however you want to write it, it's the same value).
With that being said, the ppm concentration of the juice in question is not 25ppm... it's 2,500ppm. THAT IS EXTREMELY HIGH! Based on all the studies I've read concerning diacetyl, the largest concentration observed at one of those factories was around 1,200ppm. But the concentration levels were all over the place. Some areas were several hundred, others only 100, yet others were 5-25 and some were below detectable limits. To put things in perspective, in 2009 OSHA was considering time weighted average thresholds between 0.05-1ppm and short term limits between 0.2-4ppm. They decided not to do this and, instead, basically said "we're just gonna say this isn't safe at all (effectively a PEL of 0ppm) and do a .... load more research and come back to this".
However... this is all a crapshoot... especially when it comes to us. What constitutes a "million parts" when it comes to vaping? Is it how much is in the juice? In the vapor? How much of it is even vaporized and reaches our lungs? Then you have to consider that only a very small percentage (something like 1.2%) of all those workers who were exposed to some measurable concentration of diacetyl 8hrs/day 5 day/week, came down with the disease. Some just got some asthma and shortness of breath, those symptoms went away in some people and others didn't have any adverse effects at all. There are so many variables and unknowns that it's impossible to say anything with any certainty.
Some light reading:
OSHA Direction 2011
April 2008: OSHA Convenes SBREFA Panel on Diacetyl Proposal
the scary part is what is replacing diacetyl, the replacements are worse in different ways. So the vendors that have replaced it, what have they replaced it with is the question?
So far it's been shown that many (if not all) of these "replacements" are almost identical to diacetyl, and preliminary studies have shown that they have the same adverse effects on the respiratory system. Where they differ is in the fact they are less water soluble. This means they can more easily get deeper into the respiratory system (deeper into the lungs, meaning potentially more harmful). How much this effects us as vapors I don't know. Afterall, the whole concept of vaping revolves around "inhaling deep into the lungs". I don't know of anyone who puts their PV in their nose, so we're bypassing the protective aspects of our upper respiratory system anyway... like I said earlier, it's all a crapshoot.
Before you go thinking I'm here just to scare folks, or to tell you what to vape and what not to vape, just know that is far from the case. I just saw some concerning math and felt morally obligated to correct it. I'm right there with ya! These compounds make for the most delicious juices ever conceived! Ever since I picked up a bottle of Killa Vanilla at a local shop, I've been on a mission to recreate it myself. When I finally did I realized that it was these damned butter compounds that make it so damn good (I tried a lot of vanilla flavorings that didn't have them... none of them cut it). I still have a 5ml bottle of "the good stuff" mixed up that I vape on rare occasions
It's just so good I can't help myself sometimes!
What we need is a lab that can take a PV, hook it up to a machine that can take in the vapor that comes off of it, and measure how much of this stuff ends up in our lungs.
Bruce, I commend you for tackling this issue head on and getting your juices tested and for working toward a diacetyl free formulation that still satisfies
Vape safe folks!