Propylene glycol (also known as PG) is a chemical which can be found in an extensive amount ingredient lists ranging from cosmetics, to food, to cleaning products and even car maintenance formulas. It is used in one particular ‘natural’ eyelash growth serum which is slickly advertised by an American company and it also uses other ingredients we have warned about recently. The petroleum derivative is an extremely versatile ingredient which is included in thousands of formulas of cosmetic products. It is used as a moisturiser, skin conditioning agent, a carrier in fragranced oils, a solvent and a thinner. Its use in food as an additive is very common, here it is listed as E1520. As well as foods, you can find PG in toothpaste, mouthwash, deodorant sticks, tobacco products and industrial products such as anti-freeze and brake fluid. PG is used to give lipstick its consistency of texture and other products, such as lotions or formulas containing both water and oil. It helps perfumes sustain their long-lasting fragrances and assists the foaming action of shampoos. The role of PG in skin and hair products is to help retain moisture of the skin and the prevent moisture escaping.
PG can come in more than one formulation and this is how it is very confusing. Furthermore, this gives rise to so many conflicting and controversial reports on the chemical. Propylene glycol IS a toxin. How toxic PG is, really comes down to which strength is formulated. As PG is a form of mineral oil, an alcohol which is produced by the fermentation of yeast and carbohydrates. It is classified as a carbohydrate in foods because of this. More on the formulation process is reported by Dr Axe:
Propylene glycol (often referred to as PG) is the third “product” in a chemical process beginning with propene, a by-product of fossil fuel (oil refining and natural gas processing) and found in nature as a by-product of fermentation. Propene is converted to propylene oxide, a volatile compound used frequently in the creation process of polyurethane plastics (and to create propylene glycol). Propylene oxide is considered a “probable carcinogen.” Finally, through a hydrolyzation process (separating molecules by the addition of water), you get propylene glycol.
Just seeing the words ‘probable carcinogen’ in any form of an ingredient, makes us think that we should not be taking any risks with it. Others may have more faith in other counter arguments and that choice is of course, quite rightly theirs to make. Other forms besides the food designated include an industrial grade (PGI) which is an active ingredient in engine coolants, anti-freeze, aeroplane de-icers, polyurethane cushions, paints, enamels, varnishes and as a solvent or surfactant in many other products. PG was only introduced into anti-freeze formulations as an alternative to the more toxic Ethylene glycol, which had been responsible for the deaths of dogs that had unfortunately lapped up spilt puddles of it. The pharmaceutical grade is the formulation we need to scrutinise further in relation to cosmetics. This grade is far less potent than the PGI form and thus far less potent in its level of toxicity. We must consider the dangers of it though in-regards to products either ingested or absorbed into the body via the skin.
The Agency for Toxic Substances and Disease Registry (ATSDR) state that PG takes around 48 to be broken down by the body. This does leave frequent users of such an ingredient with the risk of some level of possible build up within the body. They also state that studies of people and animals display that repeated eye, skin, nasal or oral exposures to PG for a short time can develop into irritation. As PG is an ingredient of a prominent ‘natural’ eyelash growth serum from the USA, this should be noted by potential seekers of such products. The FDA recognises PG as generally safe, as does the World Health Organization, EWG score it as a fair hazard with 3 out of 10. It does go on to state:
Other HIGH concerns: Irritation (skin, eyes, or lungs);
Other MODERATE concerns: Organ system toxicity (non-reproductive);
Other LOW concerns: Enhanced skin absorption, Data gaps
About PROPYLENE GLYCOL: Propylene glycol is a small organic alcohol commonly used as a skin conditioning agent. It has been associated with irritant and allergic contact dermatitis as well as contact urticaria in humans; these sensitization effects can be manifested at propylene glycol concentrations as low as 2%.
Animal studies had displayed no links to cancer when doses of 2-5g per 1kg of body weight were fed to the dogs and rats. On this basis the Cosmetics Ingredient Review Panel concluded there was no carcinogenic risk with low level ingestion of PG. The panel went on to recommend that PG with a concentration less than 50% should be permitted in cosmetics. Contrary to this, it was found that in formulations with much less than 50% still provoked allergic reactions in patients with skin allergies, including eczema. There are claims that cell mutation has taken place in studies in the 1980’s during invitro studies and others warn about the dangers PG poses by being able to enhance penetration of other chemicals. This is a danger that we have great concern over in-regards to many chemicals. Are there many studies to investigate such possibilities? PG is used in transdermal patches as a carrier for active ingredients to absorb into the body. The biochemist Dr. Vin warns on AntiAgingChoices.com, “PG penetrates the skin so quickly that the EPA warns factory workers to avoid skin contact, to prevent brain, liver and kidney abnormalities”.
Dr Axe goes on to warn that PG concerns are:
- Skin irritation and allergic reactions
- Potential toxicity to kidneys and liver
- Probably not safe for infants or pregnant women
- Neurological symptoms
- Cardiovascular problems
- Respiratory issues
- Potentially bio accumulative in certain cases
- May be a pathway for more harmful chemicals
If the conflicting views, opinions and studies were not enough to leave you feeling discombobulated, you can check out some of the other names that propylene glycol can come under! The following list is reported to be at least some of these:
- α-Propylene glycol
- Methyl ethyl glycol (MEG)
- Methylethylene glycol
- Monopropylene glycol
- PG 12
- 1,2-Propylene glycol
- Propylene glycol USP
- Sentry Propylene Glycol
- Isopropylene glycol
- Ucar 35
- Solargard P
- Ilexan P; Prolugen
- Trimethyl glycol
- NSC 69860
- DL-Propylene glycol
- Alpha -Propylene Glycol
- Solar Winter Ban
- Propylene Glycol USP/EP (PG USP/EP)
- Propylene Glycol Industrial (PGI)
- Dipropylene Glycol (DPG)
- Dipropylene Glycol LO+ (DPG LO+)
- Tripropylene Glycol (TPG)
- Tripropylene Glycol Acrylate Grade (TPG Ac)
- E 1520
The PG controversy will doubtlessly go on. There is a great level of conflicting views out there, although we hope that our compilation of evidence for this article gives you more clarity. PG is not needed in food or cosmetics and that should never be forgotten. Low level toxicity does accumulate and if it was one toxic chemical alone, it would still be one too many in our eyes. The fact that there are so many other chemicals in the toxic soup of formulations, means that safety studies on the ingredient alone is still not overly informative. Long-term studies on how the ingredients reacts with others and how they can deliver toxic chemicals into deeper penetration or make them more toxic, is really what are needed. As we can certainly conclude that PG is an irritant, we would avoid it and certainly in eye products. We do of course leave that choice for you to make and hopefully you can now make it in a more informed manner. We advise further reading and our reference sources are a great place to start. We will be back with another article soon and until then, keep it clean and healthy!