A great variety of properties is attributed to propylene glycol. But which of them are true?
For example, it is commonly said that propylene glycol can cause a variety of allergic skin reactions and that its penetration through the skin can cause kidney damage and liver irregularities. There are no studies that would conform such claims ever so slightly. These are just figments of the mind found on some dubious websites.
Moreover, it is said to be derived from petroleum, to have an occlusive effect on the skin and to dry up and irritate the skin.
Propylene glycol mainly emerges from the hydrolysis of propylene oxide, an intermediary reaction product deriving from propene. Propene is obtained by processing petroleum so that propylene glycol gained this way may in the broadest sense be related to mineral oil.
However, the product has in no way the characteristics of a mineral oil and it is characterized by fundamentally different properties. Propylene glycol can be also gained from vegetable glycerine. The propylene glycol used in Belico preparations is obtained from glycerine.
In fact, propylene glycol is used in hydraulic fluids and also as an antifreeze because it has such properties and is quite harmless for people and the environment. It thus replaces substances that are harmful for the environment, like PCBs. Propylene glycol is also approved as a food additive and for feeding cows. This shows the good toxicological properties of the product.
Propylene glycol is hygroscopic, attracting and binding water. Therefore, propylene glycol should never be used in high concentrations as it will then attract water from the environment, including the skin where it would then become an irritant. Therefore, propylene glycol for skin care is always used in concentrations of no more than 10 %.
Propylene glycol does not have a virtually occlusive effect because the molecule is rather small and soluble in water. It is more probable that the small molecules penetrate into the callous layer, drain the bound water and thereby hydrate the callous. This resembles the impact of glycerine which is very similar to propylene glycol.