Mention Propylene Glycol (PG) to most people and they will probably tell you that it is a toxin. On the other hand, PG comes in more than one formulation, so it needs to be clarified as to which formulation is meant.
The real question is, does it make a difference which one is used, since it is used in everything from
hydraulic and brake fluid to snack foods?
The answer is: it does and it doesn't. It is a toxin regardless of which strength is used. Propylene Glycol is a form of mineral oil, an alcohol produced by fermentation of yeast and carbohydrates. This gives it the designation of carbohydrate when used in foods.
The form most pertinent to this article is the pharmaceutical grade. This is a much less concentrated form of PG and therefore less problematic. That being stated, it is also the controversial form due to its use in products that are either ingested or enter the body through application to the skin. It is commonly used as a solvent in oral, topical and injectable drug products as well as in foods.
Though the controversy over PG wages on, it is not for lack of research. In fact many studies have been conducted, but results have been contradictory. Possibly this is because the concentration of PG in the formulation studied is not always readily apparent. Regardless, the government agencies involved have deemed it safe: The FDA includes Pharmaceutical grade PG on its Generally Recognized As Safe (GRAS) list. The World Health Organization also considers it as safe for use.
Studies on dogs and rats, which were fed doses of PG ranging from two to five grams per kg of body weight per day, showed no links to cancer. The results satisfied the Cosmetic Ingredient Review Expert Panel enough to conclude that there was no carcinogenic risk with low levels of ingestion of PG. A low level of PG was defined, and as a result, the panel recommended that only PG with a concentration less than 50% should be used in cosmetics.
Though cancer might not be a concern, it was also found that PG provoked allergic reactions in patients with eczema and other skin allergies, even in formulations of much less than 50%.
The Material Safety Data Sheet (MSDS) cites skin, liver and kidney damage that can result from contact with PG, and it gives safe handling instructions, calling it a hazardous substance. Though not specified, this is for the more concentrated industrial grade.
On the other hand, studies done in vitro tests on mammalian cells revealed that some cells underwent
mutation. Other research conducted twenty and thirty years ago documented toxic effects after repeated small doses of
In Europe, where the authorities are much more cautious about what is allowable in cosmetics and foods, propylene glycol is limited to mostly non-food uses. What food uses are allowed are very limited.