Propylene glycol is an ingredient found in many food products. It's also an ingredient found in antifreeze. If your concerns just heightened, fear not. We're going to shed light on this widely-used ingredient to give you a better understanding of its purpose.
The truth about propylene glycol is fairly complicated. Research on this substance is limited in many cases, although it is still a legal ingredient in many products, including flavored iced coffee, processed foods, personal care products, and more.
So let's begin by discussing what propylene glycol is and why it's used in such a wide array of products (see if these top teeth whitening pens contain it, as well).
Propylene Glycol: Facts
Propylene glycol (commonly referred to as PG) is the third component in the chemical process. Starting with propene, propylene is a by-product of fossil fuels (refining and natural gas processing) and a by-product of fermentation in nature.
Propylene is converted to propylene oxide, a volatile compound often used in the manufacturing of polyurethane plastics (and propylene glycol). The oxide variant is generally considered a possible carcinogen.
Finally, through the process of hydrolysis (by adding water to separate the molecules), you're left with propylene glycol.
Odorless, Colorless, and Tasteless
Propylene glycol is a synthetic liquid substance that absorbs water. It is classified by the chemical formula C3H8O2. Moreover, propylene glycol is an organic compound (a glycol alcohol), an odorless, tasteless, colorless, and transparent oily liquid.
Its other name is "propane-1,2-diol," which is sometimes used when it is listed as a compound on the ingredient label. Since it is present in food as an additive (at least in the United States), it is cited by the U.S. Department of Agriculture through "E1520." It is completely water-soluble and one of its main functions is when it's used as a carrier for topical products.
That's why propylene glycol is so prevalent in skin lotions and other beauty products. In fact, this chemical is found in thousands of cosmetics. You'll even find it in a large number of processed foods.
Another common place you will find propylene glycol is in many medicines. This is done to help your body absorb chemicals more efficiently. It is also a common ingredient in e-cigarettes (go to 'Is Vaping Bad for Your Teeth?' post), helping to increase the flavor and provide smoother inhalation.
The Problem with Research
This liquid substance is full of inconsistencies in its research. Moreover, there are many different opinions on whether propylene glycol is a dangerous toxin or a fundamentally harmless compound.
However, there isn't a clear, definitive answer to either opinion. According to a large number of studies, the effects of this chemical are rarely negative and are usually related to very large levels of intravenous doses. As a result, propylene glycol is classified as "generally recognized as safe" by the US Food and Drug Administration (FDA).
But if there's one thing researchers can agree on, it's that propylene glycol is less dangerous than ethylene glycol, which is a toxic compound still used in many types of antifreeze and other household products.
Furthermore, ethylene glycol is considered toxic and is sometimes ingested (intentionally or unintentionally). If this happens, immediate medical attention is required due to its toxic chemical makeup.
And because it has a sweet taste, the ethylene glycol in various antifreezes has caused many household pets to ingest these products and die as a result. When propylene glycol is used in antifreeze products instead of ethylene glycol, it is considered non-toxic.
However, this does little to resolve concerns among consumers. Many people are still very worried about the presence of such an ingredient in their food. This has caused an uproar in recent years, one of which was when three European countries yanked a popular alcoholic beverage off of store shelves due to it having illegal levels of propylene glycol.
But here's the real kicker for all of you reading this who live in the United States. The reason those European countries pulled the product was because the manufacturer accidentally used the American recipe! That's right, Americans who drink that particular brand of alcoholic beverage are consuming even higher levels of propylene glycol. Six times as much, in fact.
Of course, this issue doesn't start and stop with this one alcoholic drink. Consumers are regularly surprised and frustrated when they hear that their favorite foods and beverages may contain propylene glycol.
And these concerns and frustrations are only exacerbated by its presence in many other daily products. Many people are afraid of the connection between antifreeze and food, even though propylene glycol only lowers the freezing point of water (just like salt) and is only introduced into antifreeze products to replace more dangerous chemicals. Or at least, that's the going claim.
According to the assessment of the Environmental Working Group, the main body of research presently surrounding propylene glycol is considered fair. What's more, it rated propylene glycol as a "3" on its scale of health concerns. what does that mean?
It essentially means that the harm it brings is moderately low. But it's worth inserting the fact that such studies are based on older research. So, what do we know about propylene glycol to date? Read on to find out.
Propylene Glycol: Dangers
Propylene Glycol Toxicity to Liver and Kidneys
Propylene glycol is used in many intravenous medicines, including lorazepam, a medicine to reduce anxiety and seizures. This drug is usually used as a sedative during the healing process of patients with extensive burns or in patients with mental illness.
When lorazepam was taken in large doses for a long period of time, clinicians discovered kidney problems that may arise from elevated blood creatinine levels, leading further credence to propylene glycol toxicity.
Heart disease and symptoms are often related to propylene glycol exposure, partly because a few studies have attracted alarming attention. One such patient is an 8-month-old child who had a heart attack after taking four doses of topical medication for burns.
Allergic Reaction/Skin Irritation
Another typical side effect of this chemical includes mild skin irritation, including redness. Usually, this happens to people who are allergic to chemicals, and it subsides within a short time after the body has time to break down the compounds.
The CDC's toxicity profile is one area where this chemical is negatively assessed in the area of neurological symptoms. When taken orally and tested for how many chemicals were still in their system through a patch test, it was found that many people have neurological problems of varying degrees.
This includes stupor, convulsions, and other unspecified mental symptoms. As such, there is understandable concern surrounding the toxicity of propylene glycol.
Likely Unsafe for Babies and Pregnant Women
Expectant mothers are usually very cautious during and after pregnancy to ensure the health of their children. In the case of propylene glycol, there should be no difference.
Although some studies have shown that newborns and premature babies have been found to be free of the adverse side effects of propylene glycol, it is also true that babies cannot break down this compound as quickly as adults.
This is due to the enzymatic pathways that are still developing at birth. And depending on which research you trust, the developmental period can last from six months to four years. Therefore, parents should avoid products that contain propylene glycol, especially in the early years.
Breathing Concerns (Respiratory)
There are conflicting reports about the effects of inhaling this chemical. Since it is a fairly common ingredient in smoke machines (used in theater productions) and other inhalable substances, this is an important difference.
In rats, some scientists found enlarged cells in the respiratory tract, as well as some bleeding from the nose. In another case, a horse with myocardial edema died of respiratory arrest. With such concerns as these, it's understandable why anyone with breathing issues like asthma would want to avoid products containing propylene glycol.
May Serve as a Pathway
Perhaps the most worrying part of continued exposure to propylene glycol is the way it may allow other chemicals to enter your blood freely. Propylene glycol increases the tendency of the skin to absorb any substances it comes into contact with. Considering the large number of hazardous chemicals people often encounter, this may be more dangerous than the compound itself.
This chemical has enough concerns surrounding it that you may want to avoid it altogether. Given the fact that cosmetic goods aren't well-regulated in the United States, you have even more reason to research what products you use and consume.
The best practice you can employ is to use as many natural ingredients as possible. Whether in your cleaning products or food, natural ingredients ensure the safest results for you and your loved ones. For many people, the risk is simply too great to use anything else.
1. Is propylene glycol toxic to humans?
The United States Food and Drug Administration (FDA) classifies propylene glycol as generally regarded as safe (FDA 2017). In most cases, propylene glycol's toxicity is irrelevant in environmental or occupational exposures. Propylene glycol poisoning is most frequently caused by an iatrogenic propylene glycol overdose.
2. Is propylene glycol cancerous?
The Department of Health and Human Services (DHHS), the International Agency for Research on Cancer (IARC), and the Environmental Protection Agency (EPA) have not classified propylene glycol as carcinogenic. Animal experiments have not shown this substance to be carcinogenic.
3. Is propylene glycol bad for skin?
Propylene glycol is generally well tolerated by the skin and should not cause irritation. These molecules may cause irritation to the skin's lipid barrier if they are skin toxins such as pollution or harsh chemicals.