I use my 510 all day, but people need to understand that just because the FDA has cleared PG as "safe for human consumption" doesn't mean that it actually is safe in e-cigs. PG can be found in icing and skin products sure, but we are not ingesting or rubbing PG on our skins, we are vaporizing it. By doing this the avioli in our lungs are absorbing the PG into out bodies. It is a different delivery into our bodies and PG undergoes a phase change.
Obviously people dont eat a gallon of icing everyday but vapers may inhale PG for the rest of their lives. It is somewhat naive to think that if it is safe in icing (or antifreeze for that matter), than it is safe to be inhaled for years continuously.
Whenever a chemical changes phase, it may decompose. When a molecule gets energetically excited by a temperature change it may rearrange its chemical structure it achieve a lower energy level. I failed to find at what temperature PG ddecomposes at, if its temperature is high above it boiling point, than it isn't likely to decompose.
Vegetable Glycerin (VG) will decompose in a pure VG e-juice. It creates a very harmful byproduct called Acrolein. VG, or glycerol, has a decomposes at a same temperature as which it boils at.
Although the present of decomposition of VG bay be below 5%, whith long term exposure, a pure VG/nicotene e-juice is far more harmful that a PG juice.
Take a look at what MSDS says about PG:
MSDS is a far better tool for learning about organic molecules than Wikipedia. It says however:
Inhalation:
No adverse health effects via inhalation.
Chronic Exposure:
Lactic acidosis, stupor and seizures have been reported following chronic ingestion.
Aggravation of Pre-existing Conditions:
Kidney disorders.
--------\Cancer Lists\------------------------------------------------
---NTP Carcinogen---
Ingredient Known Anticipated IARC Category
---------------------------- ----- ----------- -------------
Propylene Glycol (57-55-6) No No None
So the MSDS is pretty much saying that it is generally safe,
but I don't think they knew people would be
inhaling this over years of time.
This is why the FDA needs to have some responsibility in at
least testing the effects of inhaling PG of long periods of time.
They will be testing inhalation of e-liquid vapor in lab rats.
The FDA has claimed they are not out to ban the product, they
will first do a study as to what/if are the risks to our health.