Propylene Glycol (PG)
Food-approved — but as an aerosol over years, a data gap.
⚠ Sounds harmless — it isn't
PG gilt als Lebensmittelzusatzstoff (E1520) und Pharmaka-Trägerstoff — als Aerosol über Jahre eingeatmet ist die Datenlage allerdings dünn, und bei Überhitzung (hohe Wattzahl, Dry Hits) entstehen Formaldehyd, Acetaldehyd und Acrolein.
At a glance
- Also known as
- PG · 1,2-Propandiol · Propan-1,2-diol
- CAS number
- 57-55-6
- Toxicity
Low
- Carcinogenic
- Not classified for cancer
- In cigarette smoke
- In vape aerosol
- Hauptkomponente, typisch 30-70 % des Liquids; pro Zug 1-3 mg
What is Propylene Glycol (PG)?
Propylene glycol (PG) is a colourless, slightly sweet, syrupy liquid. Approved in the EU as food additive E1520, considered safe as a carrier in pharmaceuticals, cosmetics and theatrical fog machines for oral and dermal intake. In e-cigarette liquids, PG is — along with vegetable glycerin — the most important carrier, typically making up 30 to 70 percent of the liquid.
Why is Propylene Glycol (PG) in cigarettes?
PG serves two functions in vape liquids: it dissolves nicotine and flavours, and when heated produces the characteristic throat hit — the mild scratching in the throat many smokers experience as a stimulus moderator. Each puff delivers 1 to 3 milligrams of PG as aerosol into the lung. This route of intake is new — oral and dermal intake via food and pharma has been studied for decades; long-term inhalation as aerosol has not.
What Propylene Glycol (PG) does to your body — short term
PG acutely irritates the mucous membranes of the upper airways, showing as dry mouth, scratchy throat and increased salivation. Many vape beginners report exactly these symptoms in the first weeks, because PG draws moisture from tissue (it's a humectant — binds water). This irritation usually disappears with adaptation, which doesn't mean the effect has disappeared, but that the mucosa has adjusted.
What Propylene Glycol (PG) does long term
Scientific data on long-term PG aerosol inhalation is thin. Studies on actors and stage personnel with years of fog-machine exposure show elevated airway symptoms but no clear severe damage. However, at high wattages or in dry hits, PG breaks down to formaldehyde, acetaldehyde, methylglyoxal and acrolein. These pyrolysis products are the actual concern, not PG itself.
Where else do you know Propylene Glycol (PG) from?
You know PG from food packaging as E1520 (carrier for flavours, colours, sweeteners), as the fog in stage and concert fog machines, and as antifreeze in HVAC systems. In pharma, PG is the standard carrier for many intravenous and oral active ingredients — for example in diazepam injections and some cough syrups.
How it compares
There's no DFG MAK value specifically for PG aerosol; NIOSH recommends 10 mg/m³ as a shift value for PG mist at workplaces. A vaper with 300 puffs per day takes in roughly 0.5 to 1 gram of PG — a high daily dose, but the critical question isn't the amount of PG itself but the pyrolysis products formed during every aerosolisation.
Workplace exposure limit: kein DFG MAK; NIOSH-Empfehlung 10 mg/m³ (8h, Aerosol)
These substances you want out of your body.
Flamy walks you through quitting, step by step.
Download the Flamy app