Hi Guys,
It might interest you to know that this "report" looks very, very familiar. The same firm completed an almost identical exercise for another company... TW, to be precise. Unfortunately, this report has been littered with a number of errors which should have been rectified before it was published. Still, that's life!

As it happens, the proposed TWA-exposure to PG is some 470-odd ppm, which is one of the highest for any chemical used in industry. PG may cause throat irritation in some, but its effects are mild and not a long-term risk to health; unlike something of the nature of Carbon Tetrachloride (a known carcinogen), for example. This is where the internet can be both a blessing and a curse. People on a number of forums have freaked out over diacetyl, but ignorance has remained with respect to the route-causes of the cases of bronchiolitis obliterans reported... and this is despite the information being freely available to those who want to go "digging" for it. In the most notorious incidents brought to the public's attention, the afflicted individuals were exposed to prodigious levels of the compound and safety controls in the workplace were either non-existent or poorly observed. That, alone, makes a huge difference to outcomes... It's the difference between someone walking past a car when the exhaust is running and someone sitting directly in front of its path for extended periods of time and breathing in the whole job lot.
The worst that PG will do is to cause mild throat irritation in some people who are sensitive to it. Like some here, Glycerol exerts an effect on me whilst PG doesn't. Both, in the grand scheme of things, are safe... and a damned-sight safer than cigarettes, air fresheners, air-sprays, insecticide aerosols, und so weiter...
The e-cig bandwagon, thankfully, is slowly gaining momentum... and common sense will eventually prevail.
Ta ta for now
J
