The ingredients listed on some food products may sound as though they belong in a chemistry lab rather than in grocery store goods. Propylene glycol is one such example, found in thousands of products from salad dressing to dog food, cosmetics and antifreeze. This synthetic chemical, generally regarded as safe for food use, helps products maintain their moisture, consistency and texture, which is why it’s commonly found in packaged consumables and household products.
Propylene Glycol Basics
Propylene glycol begins its life as a chemical called propene, which is a byproduct of the fuel industry or the fermentation of plants. Propene is converted into propylene oxide, a potentially harmful chemical that is also used to make polypropylene-based plastics. Adding water to propylene oxide, also known as hydrolyzing it, creates propylene glycol.
Propylene glycol is a diol alcohol, so it is sometimes listed on products as 1,2-propanediol or propane1,2-diol. It also shows up on some ingredients listings as E1520, methyl ethyl glycol, trimethyl glycol or 1,2-dihydroxypropane, making it trickier to determine which products contain propylene glycol.
On its own, propylene glycol is a clear, odorless liquid that is a bit more syrupy than water. It doesn’t add much, if any, flavor to foods, which is another reason why it’s commonly used in packaged food product, medications and personal-care goods such as deodorant and perfume.
Propylene Glycol Uses
Propylene glycol’s inherent traits make it beneficial to product manufacturers on many levels. The chemical is used to thicken items, keep them moist and help prevent caking. As an anti-caking agent, it comes in handy for keeping dried and powdered items such as soup mixes and grated cheeses from sticking together. Oddly enough, it also helps blend items together, such as the oil with the water-based ingredients in some salad dressings.
Propylene glycol uses also include stabilizing and preserving all sorts of products, increasing their shelf life. Some manufacturers add propylene glycol to ensure even flavor and color distribution in packaged foods. It’s even used in the liquid that creates smoke for a smoke or fog machine and to improve the “smoothness” of vaping or e-cigarette liquids.
This chemical is also used as a solvent in the paint, plastic and food industries. Solvents help dissolve other chemicals.
Propylene Glycol in Food
Since propylene glycol has numerous properties potentially beneficial to packaged foods, its use is quite common in food products designed to have a long shelf life. The Food and Drug Administration (FDA) says propylene glycol is “generally recognized as safe” for use in foods, pharmaceuticals and cosmetics.
The United States government regulates how much of this chemical is deemed safe for food use stateside. In the U.S., up to 50 grams propylene glycol per kilogram of food product is considered a safe amount, while the European Union has stricter regulations, limiting it to 3 grams per kilogram for foods and beverages.
In one instance, an alcoholic beverage company received a bit of backlash in the European Union when it accidentally sent the U.S. version of a cinnamon whisky to several European countries. The drink was pulled from shelves in several countries for containing too much propylene glycol, even though that same formulation would be considered safe in the States.
Foods Containing Propylene Glycol
Many foods containing a laundry list of ingredients also contain propylene glycol. Some of the more common packaged foods containing it include dried soups and seasoning blends, marinades and salad dressings and baking mixes for products such as cakes, pancakes and muffins. In the beverage world, soft drinks, flavored teas, powdered drink mixes and alcoholic beverages may also contain propylene glycol. It is also used in some flavoring extracts for baking, as well as in some types of food coloring.
Propylene glycol is also quite common in fast foods, bread-based products, highly processed snack foods, flavored popcorn and cake frosting. Pre-made, mass-distributed baked desserts such as brownies, cakes and cupcakes may also contain this chemical. Even some ice cream flavors contain propylene glycol.
Marshmallows, dried coconut shreds and even some cans of nuts contain propylene glycol, as it helps retain an acceptable moisture level in these foods.
Cosmetic and Pharmaceutical Use
Propylene glycol is quite common in cosmetic and personal care products, as well as in some medications, for the same reasons it’s used in packaged foods. This chemical helps prevent some cosmetics from drying out or caking while helping ensure even color distribution and consistent texture. It is also used in some body fragrances, deodorants, toothpastes, shampoos and hair dye products, as well as in hair removal creams and hair mousse.
Some mascara also contains propylene glycol, as well as cosmetic concealers, aftershaves and cuticle-treatment products. Even diaper ointments and baby lotions contain propylene glycol; in other words, it’s found in products dotting the shelves of nearly every aisle in a drugstore or grocery store.
In the pharmaceutical world, propylene glycol makes topical, intravenous and oral medications more soluble. When used in a lotion or ointment, propylene glycol increases the skin’s ability to absorb whatever it’s applied to it, which could help medications work better.
Although a rare occurrence, some skin irritation could occur among those sensitive to this chemical. This may also happen after frequent skin exposure to propylene glycol. Those sensitive to propylene glycol may develop a rash or contact dermatitis, even if using a shampoo or moisturizer containing the chemical.
The Antifreeze Connection
The fact that propylene glycol is used in both antifreeze and food products may seem alarming, but the reason it’s used in both substances may come as a surprise. Another chemical with a similar name, ethylene glycol, was once widely used in many brands of antifreeze to lower the freezing point of the product.
This chemical, much more toxic than propylene glycol, also smells sweeter. Pets and wildlife coming across pools of ethylene glycol antifreeze outdoors found the scent enticing and would drink it, to their demise. Some antifreeze manufacturers switched out the ethylene glycol for propylene glycol to make the product much safer and less appealing to pets.
Even though considered safer than the ethylene glycol versions of antifreeze, it should still not be left out where pets, children or even stray animals may consume it. Antifreeze contains other chemicals and dyes and is not designed for consumption.
Other Household Product Uses
Propylene glycol is also found in other household goods besides antifreeze, foods, medications and personal-care products. This ingredient is found in some soaps, including coconut-oil-based soaps. It’s also in spray-based car tire inflators, vinyl and rubber conditioners, foaming tire protectants, automotive scratch removers and leather protectants.
Propylene glycol is also in some hand cleaners designed for garage use, as well as in air fresheners and construction adhesives. Foaming degreasers, floor sealants, wall spackling and crack repair products and wood stain also contain this chemical. Milk paint, acrylic paint and enamel paints also contain propylene glycol, and the list doesn’t stop there.
Caulk, ready-mixed tile grout, wallpaper stripper, boat epoxy and numerous laundry detergents and stain removers contain propylene glycol. Dishwashing detergent, metal polish and rust or soap scum removers also contain this chemical.
The U.S. National Library of Medicine’s website offers an exhaustive list of common household products containing propylene glycol. The list includes specific brand names for easy reference, although the list is not in alphabetical or even categorical order.
Propylene Glycol Dangers
Even though propylene glycol is generally considered safe, it may cause health concerns for those sensitive to it or for those with other existing health issues. Close to half of this chemical is excreted after it reaches the kidneys in a healthy human body, with the rest of the chemical converting into lactic acid. This means that for most people, exposure to safe levels of propylene glycol, even on a repeated basis, is not cause for concern.
Toxicity from ingestion has been reported only once, when a man drank the contents of an ice pack containing propylene glycol, which most likely was not of a food-grade quality and may have contained other potentially harmful chemicals. Another potential instance involved a man that consumed so much of a cinnamon whisky containing this chemical that he became unconscious, although the report did not indicate whether propylene glycol contributed to his condition.
For even an otherwise healthy individual, consuming dangerously toxic levels of propylene glycol could lead to a buildup of lactic acid, which could cause kidney failure, especially if the chemical is consumed in dangerous quantities on a repeated basis.
Kidney and Liver Concerns
Individuals with kidney or liver disease may want to limit or completely avoid products containing propylene glycol, as their bodies may not be able to process the chemical properly. High doses of some medications such as lorazepam may also be of concern for those with existing health issues, as the medicine may introduce potentially problematic amounts of propylene glycol into the body over the course of a few days.
Potential Dangers for Kids and Moms-to-Be
Propylene glycol should also be largely avoided by pregnant women, infants and toddlers. Compared to other people, these groups have low amounts of the enzyme that breaks down propylene glycol in the body, which means they could develop toxicity if exposed to large amounts of the chemical through medications. An infant takes three times as long as the typical adult to expel propylene glycol from the body. Even an oral or injectable vitamin solution containing large amounts of propylene glycol could cause seizures or irregular heartbeat, especially in young children.
Known by Other Names
It’s not always easy to tell if a product contains propylene glycol because is often isn’t listed as such on an ingredients label. Besides the previously mentioned terms, this chemical may also show up as 1,2-Propylenglykol, methyl glycol, alpha-propyleneglycol, isopropylene glycol and Dowfrost, a branded version offered by Dow Chemical Company.
To prevent confusion when trying to avoid products containing propylene glycol, avoid any product containing chemicals with terms similar to the aforementioned. If unsure, search the specific chemical online to determine whether it is really propylene glycol.
Some forms of propylene glycol are made from vegetable-based products, which is also good to know if you’re trying to avoid petroleum-derived products. In most cases, companies using the vegetable-based chemical clearly state so on their websites and packaging materials. Tom’s of Maine is one such company.
Another way to avoid propylene glycol products is to ask for ingredients listings for any medications, including prescription drugs and vitamin solutions. Carefully read package listings on personal care products in particular, as so many of these, even those labeled as “natural,” contain the chemical. Better still, whip up recipes from simple ingredients as often as possible and avoid junk foods, processed food mixes and even frozen meals that often contain an abundance of additives.
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