What is propylene glycol?

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.