What is Propylene Glycol?
Date Posted: January 23, 2012
What is propylene glycol? We are asked this question repeatedly and there is a lot of misinformation about propylene glycol and e-cigarette ingredients circulating in the media. To help answer this question, we have gathered together this list of information from reputable sources in one place.
-Propylene glycol is a clear, colorless, slightly syrupy liquid at room temperature. It may exist in air in the vapor form, although propylene glycol must be heated or briskly shaken to produce a vapor
-Propylene glycol is practically odorless and tasteless
-Propylene glycol is a chemical made by reaction of propylene oxide with water
-Propylene glycol has had an unsurpassed reputation for safe use in a wide range of consumer products, including food products, animal feed, cosmetics and pharmaceuticals, as well as industrial applications
-It’s used as a stabilizer (to keep things held together, and keep them from evaporating), and to keep foods moist. It’s used in many of the foods that we eat, and the FDA deems it safe for human consumption
-Industrial grade propylene glycol is an ingredient used to make non-toxic antifreeze and deicing solutions for cars, airplanes, and boats; to make polyester compounds; and as solvent in the paint and plastics industries.
The point above needs a special note, since PG has been vilified in the media for being an ingredient in antifreeze. These reports fail to mention that they are referring to non-toxic antifreeze, giving consumers a false impression. This is a scare tactic used by the media, those who are misinformed and organizations against e-cigarettes. More information is below in the FAQ.
Propylene Glycol (PG) in e-cigarette cartridges:
-The content of the V2 Cigs liquid solution found in cartridges includes three primary ingredients: nicotine (except in Zero nicotine carts), flavorings, water and pharmaceutical-grade propylene glycol. You can download and view our ingredient list right on our website: http://www.v2cigs.com/pages/downloads
-Propylene glycol is added to the V2 liquid solution as a vaporizable base to dilute pure liquefied nicotine
-Because of its water-retaining properties, propylene glycol is the compound of choice for delivering atomized medications. It has been used in asthma inhalers and nebulizers since the 1950’s
-In e-cigarettes, propylene glycol allows atomization to take place at substantially lower temperatures than required for a tobacco cigarette and will also help carry / deliver the nicotine when the vapor is inhaled
-While the contents of the liquid solution found in cartridges may vary depending upon brands, the major ingredients usually remain the same.
Features of propylene glycol:
-Serves as a solvent
-Connects and stabilizes insoluble fluids (emulsifier)
-Helps to bind and transport other substances (excipient)
-Holds and dissolves active ingredients equally in a medium
-Attracts/holds water/moisture (hygroscopic)
-Reduces the freezing point
-Increases the boiling point
-Offers outstanding stability with high flash and boiling points
By emulsifying (mixing) active ingredients, which otherwise would not mix with one another, the propylene glycol creates a stable homogeneous fluid that will allow the intended final product, be it a face cream or shampoo, for example, to do its job.
Safety of propylene glycol:
-It has been used safely for more than 50 years, including in health-sensitive products such as food, cosmetics and pharmaceuticals, where the molecule mainly serves as non-active ingredient or carrier of other substances
-Studies have proven that propylene glycol has a very low degree of toxicity
-In the body, propylene glycol is rapidly converted into lactic acid, in a similar manner to what happens with sugar (energy) in the muscles during sports
Applications of propylene glycol:
-To carry flavors in food and drinks
-To make face creams, body lotions, deodorant-sticks, lipsticks and many other cosmetic articles soft, moist and consistent
-To stabilize foams in cosmetic and healthcare products
-To help pet and livestock feed retain its moisture and taste
-To act as a carrier of active ingredients in vaccines, cough relief syrups or gel capsules to help deliver this substances within the body for treatment and prevention of diseases
Applications of propylene glycol in cosmetics and toiletries include products in:
-Personal care: bath and shower soaps, gels, face cleansers, shaving foams, after shave, antiperspirant deodorants, roll-ons, sticks, lipsticks, fragrances, perfumes
-Skin care: hand, body and facial moisturizers, sunscreen products
-Hair care: shampoos, conditioners, styling gels
-Oral care: mouthwashes, toothpaste
-Baby care: wipes, antiseptics
-Solvent and carrier of flavor or color in the food and beverage manufacturing processes, to make drinks, cookies, cakes, candy
-Thickener, clarifier and stabilizer in food and beverage such as beer, salad dressings or baking products
Applications of propylene glycol as pet and cattle feed additive* include its use as a(n):
-Humectant to provide moisture and taste. ” A humectant is a substance with the ability to attract and hold water in a formulation ”
-Solvent, stabilizer and preservative to keep the feed suitable for longer use
-Additive for increased energy provision
- * Not approved for use in cat food
Some Pharmaceutical applications include:
-Therapeutic drugs and medicines, such as vaccines or cough syrup
-Vitamins and hormones
Industrial propylene glycol can be used:
-As aircraft deicer, enabling safe global public transport
-In non-toxic antifreeze
-In paints and coatings, providing sustainable weather and wear protection
-In liquid detergents, supporting hygienic conditions
-As a basic building block in the production of other formable plastics such as unsaturated polyester resins (UPR) used in furniture, heavy-impact surfaces (floors, kitchen, bathroom) or windmill blades
Propylene glycol and Antifreeze:
-Antifreeze has traditionally been manufactured with ethylene glycol. This product is highly toxic and poisonous
-On the other hand, propylene glycol is used in certain types antifreeze labeled as “non-toxic antifreeze”. Because propylene glycol is considerably less toxic than it ethylene glycol counterpart, it is now used in antifreeze where ethylene glycol would be inappropriate, such as in food-processing systems or in water pipes in homes when incidental ingestion may be possible
Has the federal government made recommendations to protect the human health?
The Food and Drug Administration has classified propylene glycol as GRAS, “generally recognized as safe,” which means that it is acceptable for use in flavorings, drugs, and cosmetics, and as a direct food additive.
Which products contain propylene glycol?
Propylene glycol is used in a large variety of every day convenience and care products, such as in cosmetics and toiletries, food, animal feed, and pharmaceuticals, as well as in a number of industrial applications.
How can I come in contact with propylene glycol?
Most people will come in contact with propylene glycol during their normal everyday life, when using personal care articles like creams, sprays, lotions, when enjoying soft drinks, sweets and other foods, or when taking medication or being vaccinated.
What happens with propylene glycol in the body?
In the body, under conditions of normal low exposure, propylene glycol is quickly metabolized and eliminated. Its metabolic pathway is comparable to that of sugar: propylene glycol is rapidly converted into lactic acid, just like what happens with sugar (energy) while exercising. The lactic acid formed by propylene glycol ingestion is then discarded by the body via the urine.
Is there a danger associated with ingestion in large quantities?
Propylene glycol is used professionally by manufacturers of consumer and industrial products, but it is not available to consumers as a pure substance. Under normal circumstances, it is impossible to ingest propylene glycol in large amounts, and exposure to propylene glycol via consumer products is extremely low. In addition, studies have shown that propylene glycol has a very low degree of toxicity. In fact, from a toxicological point of view, alcohol is actually more toxic than propylene glycol.
Can propylene glycol have negative health effects if consumed over long periods in time in small amounts?
Propylene glycol has been used safely for more than 50 years in a large variety of applications. Studies have shown that propylene glycol has a very low degree of toxicity. No negative health effects from exposure to small amounts of propylene glycol have ever been observed. The FDA has approved the use of propylene glycol in sensitive applications such as in pharmaceuticals, foods and cosmetics, and thus confirmed its safety.
Can I be sure that industrial propylene glycol will not be used for pharmaceutical applications?
The quality and purity of both industrial propylene glycol and pharmaceutical grade propylene glycol is very high. For propylene glycol intended for use in pharmaceutical applications, utmost care is placed on fulfilling specific strict rules for the production, transport and hygiene of the product to be used in sensitive applications like in food or cosmetics.
How can a deicer be used in food or in cosmetics?
Deicer (for de-icing) is not used in food or cosmetics. The different “natural” functionalities of propylene glycol make it a substance which can achieve various results. In the deicer, it is the ability to reduce the freezing point, in cosmetics the ability to dissolve, emulsify, or carry active ingredients in substances. Industrial propylene glycol is used is used for de-icing while pharmaceutical grade propylene glycol is used in cosmetics. Propylene glycol really becomes active when mixed with other ingredients and depending on what those ingredients are, different results will be achieved. Hence, deicer and cosmetics both contain propylene glycol but are mixed with different ingredients which will give way to different results.
How pure is pharmaceutical propylene glycol?
Pharmaceutical grade propylene glycol has a very high purity of more than 99.5% – which is extremely high for a chemical. However, the most important requirement to keep the degree of purity of pharmaceutical grade propylene glycol is to thoroughly respect the hygiene regulations and manufacturing standards of production, transport and further processing of the product.
Is propylene glycol safe for human health? Can it give me an allergic reaction?
It may be possible to develop an allergic reaction to propylene glycol and some individuals allergic to the product may exhibit different symptoms. However, pharmaceutical grade propylene glycol has been safely used for decades in a large variety of consumer products, including more than 4000 cosmetics and toiletry products. Over this long period of time and a large variety of products, there has been no evidence of significant adverse effects.
How likely is propylene glycol to cause cancer?
Propylene glycol does not cause cancer. The US Department of Health and Human Services (DHHS), the International Agency for Research on Cancer (IARC), and the and the US Environmental Protection Agency (EPA) have not classified propylene glycol for carcinogenicity. Animal studies have not shown this chemical to be carcinogen.