Propylene glycol is a tasteless, colorless and odorless synthetic liquid capable of absorbing water and is slightly more viscous than water. It is a common ingredient found in a variety of products that are used in daily life. These include pharmaceutical products, cosmetic products, antifreeze and food products.
The substance has had a contentious reputation due to fears of possible toxicity when used. There was heightened public fear when it was discovered that propylene glycol is present as an ingredient in both antifreeze and food. This then sparked fears that food containing it was toxic. These were debunked however as the propylene glycol present in food is considered safe to consume and differs from the antifreeze product. The substance is safe to use and consume in the food according to the Food and Drug Administration and up to certain amounts according to the European Food Safety Authority.
It is generally safe to use in cosmetics, it is considered nontoxic to the skin. It has been used safely on the skin for decades.
There are also worries about the safety of its use of medicine. However, there has been no concrete evidence on propylene glycol causing harmful effects or reactions when administered inappropriately low amounts.
How is Propylene Glycol Used in Food?
The presence of propylene glycol in food is mainly as an emulsifier to help stabilize food, as an additive to help add flavor and color to the food by being a solvent for other ingredients, and as a humectant to help maintain moisture on the food for extended periods of time. Due to its state of being free of odor, taste and color; it can perform its functions without affecting other ingredients.
A real world example would be that it helps keep processed and prepared food such as cakes and candies to last longer. Other examples are:
- Ice cream – acts as an antifreeze to keep the ice cream’s shape and flavor.
- Soft drinks – the flavor of soft drinks are maintained when kept using propylene glycol.
- Sweeteners – prevents moisture and mold from forming.
This also gives a sweetness to the food that lasts. With proper preparation and safe amounts, there should be no side effects when consuming products that contain propylene glycol.
The only rare cases wherein an adverse reaction to the product would occur is if the person consuming the product is allergic to the substance. Skin rashes are the common reaction. Adverse reactions can also happen if one willingly consumes a large amount of products containing it. Even then, incidents with products containing it are often not caused by the presence of it.
Care must be taken by those with kidney and liver conditions however. The liquid is easily absorbed then excreted by the body through urine. However, those with the mentioned conditions may have difficulty in cleansing the substance from their body.
How is Propylene Glycol Used in Medicine?
In medicine, propylene glycol acts as a solvent for oral, injected, and topical pharmaceutical products. Additionally it is a excipient in medical products, acting as a vehicle or medium for other drugs and substances to use. It has been used in this manner for nearly 50 years with only very rare cases of toxicity.
Medical use is where the highest risk of overdosing is possible due to poor estimation and dosage. It is highly recommended to avoid using the product in babies as they are of higher risk in toxicity.
In theory, people suffering from liver problems and impaired renal function must avoid using the substance. This is because they are more susceptible to accumulation in the serum.
Adults can be administered propylene glycol for a long term period without any adverse effects, as well as children below 5 years of age.
Infants that are a few months old must be given special care. Their total body clearance is low and the risk of toxicity is higher.
In general practice, the safety limits of administering any substance with propylene glycol is well known and there is little worry needed with it.
Where Else is Propylene Glycol Used?
Propylene Glycol can be found in many varieties of products. To list a few:
- It is used as moisturizer in cosmetic products such as lotions and ointments.
- A dispersant in fragrances.
- Fog machines
- E-cigarettes and vapes
- Printing Ink
- Deodorant Sticks
- Simulated Smoke
In regards to the the use of propylene glycol in fog machines, simulated smoke, e-cigarettes and vapes, there has been no evidence of long term damage from inhaling the substance. Multiple studies have shown that exposure and inhalation of propylene glycol in low doses show no damage. However, frequent exposure in high doses (working around fog machines on a constant basis) can lead to mild respiratory problems. Mainly nose, throat and breathing-related symptoms along with inflammation to the vocal chords. According to a study by the National Institute for Occupational Safety and Health there is no cause of concern on propylene glycol causing asthma, at most anyone exposed will only have irritant effects with no lasting damage.
Enivronmental damage however is a challenge when dealing with the substance. The substance has shown to be non-toxic to most aquatic and terrestrial animal and plant species, but precautions and regulations are still undertaken to ensure the safety of flora and fauna when it comes in contact with the liquid.
Other research has shown that though there is a set baseline for the detection levels of it, there is fear that there is still damage dealt with present contamination. The substance is known to cause degradation in surface waters and affect aquatic life by consuming oxygen needed by the organisms for survival.
Despite the rocky reputation (including being named the American Contact Dermatitis Society’s Allergen of the Year for 2018) and fears surrounding the use of propylene glycol, decades of use of the substance and repeated research has shown that there is no worry needed as it is safe to use. More research must be done however in regards to the possible environmental impact of the substance.