The world's one billion smokers provide important clues as to the effect of inhaled diketones. This has been discussed at length in this thread and I won't repeat it unless you ask. Except to suggest it is a 50 Ton Elephant in the room. Ignoring smokers is ignoring a 50 Ton Elephant.
If, however, the facts do not matter then I guess the experience of smokers can be safely ignored.
It was suggested here and in other threads that it might take 40-50 years for diketones to prove deadly. That logic can be applied to every compound in vaping. And in every other aspect of life. There is nothing wrong with dealing with the unknown by abstaining. But then you would have to abstain from cell phone use, wireless network use, GMO foods, and how many other aspects of modern life?
A couple diketone/popcorn factory facts that have been misstated and otherwise ignored: The workers thought to be most at risk (both mixers and quality control workers who popped 100 bags of popcorn each day) showed up to around an 83% incident rate of BO. For ALL the factory floor workers, mostly exposed to far lower levels, the MEDIAN employment time before the 20% or so affected showed significant loss of lung function, per spirometry tests, was 1.5 years. That is not the outliers or exceptions, that means half the affected workers were affected in 1.5 years or less, and the most rapid cases were 5 months. Within 10 years some were so badly affected they were candidates for lung transplants. The onset of lung disease was so fast that NIOSH, over a period of 5 or 6 years, was able to track that onset (in newly employed workers) in the course of multiple rounds of attempts to mitigate the damage. They only needed a year or two before they saw new employees affected.
In the meantime, smokers do not routinely come up as candidates for lung transplants after 1.5 to 10 years of smoking. If they did, you would see large scale reports of smokers in their 20s with significant lung damage, many needing lung transplants. Yet smokers inhale 334 µg of diacetyl with each cigarette. The factory floor production line workers (at least risk) were exposed to about 2700 µg per day, or about 8-9 cigarettes, less than a half PAD, yet many had serious lung damage.
This Harvard report neglects to mention that most of the juice they studied, that they included in their headline blaring 74% containing hazardous diketones, neglects to mention that only 1 or 2 of over 50 samples had more than 10 µg/ml or so. Most were trace amounts, near the limits of detection. THAT is what I have the most problem with in the report.
The facts matter. Even the smoker's facts matter. A lot.
Source- see page 4-5 of this NIOSH report:
http://www.cdc.gov/niosh/hhe/reports/pdfs/2000-0401-2991.pdf
Good science almost always simplifies seemingly contradictory observations and accounts for all the facts. For thousands of years, people looked up and observed that the stars appeared to revolve around the Earth. They did have to ignore the occasional but periodic retrograde motion of the planets and some came up with increasingly preposterous speculations to explain how the planets could do loops as they traveled around the supposedly Earth-centric center of the universe. That was "bad science". It took a couple of very brave guys to move the center of the universe at least to the sun, thus explaining that retrograde motion (as well as other anomalies) in a very simple way. That was good science in action.
