Would you consume a food product if it contained the same ingredient that is found in antifreeze, paint, and plastic? Of course not. Yet propylene glycol is used in thousands of processed food items, as well as medicines and cosmetics.

Propylene glycol is a petroleum-based, colorless, creamy liquid that has a slightly sweet taste. While some people claim that it is harmless, others believe it is responsible for diseases like cancer.

Although the US and European food authorities have declared it generally safe for use, it has been the focus of controversy for years.

Read on to know more about this controversial product and whether it is dangerous to your health.

What is propylene glycol?

Propylene glycol is a synthetic food additive and has the chemical formula C3H8O2. It is made from propene (a byproduct of fossil fuel) through a chemical process.

Propene is first converted into propene oxide, which is used to create polyurethane plastics. Propene oxide then goes through a hydrolyzation process to get propene glycol.

Propylene glycol (1,2-propanediol) is an organic compound (a diol alcohol) which is usually a tasteless, odorless and colorless clear oily liquid. It is hygroscopic and miscible with water, acetone, and chloroform (1).

Where and why is it used?

Food products

Propylene glycol is often used in foods to maintain their moisture and flavor for a longer time. It is used in drink mixes, soft drinks, popcorn, bread, dairy products, dressings, cake mixes, dried soups, and food coloring.

Here are some of the ways how this food additive is used –

Moisture preserver: It is used in marshmallows, nuts and coconut flakes to maintain a specific level of moisture and to prevent them from drying out.

Anti-caking agent: It prevents food components in powdered soups and grated cheese from clumping and sticking together.

Emulsifier: It is used in salad dressings to prevent ingredients like oil and vinegar from separating.

Shelf life: It protects food from deteriorating and extends their shelf life.

Cosmetics

Propylene glycol can be found in many cosmetics and personal care products like skin moisturizers, mascara, toothpaste, deodorants, and hand wash.

It is used to emulsify oil-based components to water-based components. It also helps prevent cosmetics from melting in the high heat and freezing in low temperatures.

Medications

Propylene glycol is also found in many medicines as it helps the body absorb the chemical more efficiently. It acts as an emulsifier in topical creams and injectable drugs. It is also used as a solvent for the active ingredients in many medications.

Industrial use

Propylene glycol also has many industrial applications. It is used in the production of polyester fiber. The military uses it to form smokescreen. It is also used in liquid detergents. Military and commercial airlines also use it for de-icer for planes.

Is propylene glycol safe?

The fact that we consume the same product that is used to de-ice planes has got many people worried. However, according to the assessment by the Environmental Working group, propylene glycol presents a moderately low health hazard (2).

Though this chemical can cause some issues related to allergies, it does not cause cancer or reproductive problems.

Another factor that we must consider is that industrial grade propylene glycol is used in products like antifreeze. In foods, on the other hand, pharmaceutical grade propylene glycol is used.

Propylene glycol is not bioaccumulative, which means that this chemical does not accumulate in the body over time to create toxicity.

According to a report by the Center for Disease Control and Prevention, there are not many major health concerns linked to the use of propylene glycol.

However, most of this research was done on animals like rats, horses, and monkeys. The study also includes the effect of oral exposure to propylene glycol on the respiratory, cardiovascular, gastrointestinal, musculoskeletal, hepatic, renal, endocrine, dermal, ocular, and body weight effects in humans.

Dangers of propylene glycol

1. Skin irritation

Propylene glycol can produce an eczematous skin reaction that is toxic or allergic. During one study when researchers tested 84 people with 100 % propylene glycol, 12 had an allergic reaction while seven had an irritant reaction. (3).

However, these reactions are mild, and they subside after the body has had time to break down the compound. In some cases, propylene glycol can also cause conjunctivitis if exposed to the eye and facial area.

2. Toxic to liver or kidneys

While adults with normal kidney and liver function are able to process propylene glycol efficiently, those with reduced kidney or liver function should avoid this chemical.

In people with kidney or liver disease, this can lead to building up of propylene glycol and lactic acid in the bloodstream, which can lead to toxicity (4).

Lorazepam, a seizure-treatment medication, also contains propylene glycol. When this drug is given in large doses over an extended period, it can lead to kidney issues and increased creatinine levels in the blood (5).

So, it is advisable for people with liver and kidney disease to use drug alternatives for propylene glycol.

3. Unsafe for pregnant women and infants

Pregnant women and children under that age of four have deficient levels of alcohol dehydrogenase. This enzyme is needed for the breakdown of propylene glycol (6, 7). So these people can develop toxicity if they are exposed to propylene glycol.

The enzyme pathways of babies are still in the developmental stage at the time of birth, so they take three times as long to propylene glycol from their blood (8).

There have been case reports where premature infants were injected with large doses of propylene glycol, and this resulted in seizures (9). Pregnant women and infants should not ingest propylene glycol.

4. Increased risk of heart attack

Exposure to propylene glycol can also lead to an increased risk of heart attack. When propylene glycol in injected in large amounts or too quickly, it causes a drop in blood pressure and the heart rhythm also gets affected (10).

In one case an 8-month-old infant was treated with four dozes of silver sulfadiazine, which contains propylene glycol, for treating burns that covered 78 percent of his body. The infant suffered a heart attack, which leads to brain damage (11).

Specific animal-based studies have also shown that propylene glycol can cause low blood pressure, decreased heart rate and even cause the heart to stop (12, 13).

5. Neurological problems

Propylene glycol can also cause neurological problems. In one case a 39-year-old woman with epilepsy developed propylene glycol poisoning (14). Even infants who are given injectable medicines develop seizures due to propylene glycol toxicity.

During one study when 38 patients were given 2 to 15 ml of propylene glycol, some of the patients developed nausea, vertigo and a curious sensation (15).

In another cat-based study, when cats received a high dose of propylene glycol, they developed a decreased mental activity, mental depression, and moderate ataxia.

6. Respiratory problems

Propylene glycol is used in smoke machines and e-cigarettes. Though it is generally considered safe for consumption, inhalation may be a different case.

According to one study, when rats inhaled propylene glycol, they developed sensitive eyes and noses, and it also caused bleeding in one case.

During on research when 27 asthmatic people were exposed to propylene glycol in a slight stimulator, they observed some irritation in the upper airway, and some coughing (16).

7. Increases the propensity to absorb chemicals

Constant exposure to propylene glycol can provide a free pass for other chemicals to enter the system. Propylene glycol increases the ability to absorb any chemicals that come in contact with it, and this can make exposure to other chemicals even more dangerous.

Ways to avoid propylene glycol?

Although propylene glycol is generally considered safe, it can lead to medical issues in some cases. So to protect your health, you must avoid exposure to propylene glycol whenever possible.

Here are a few simple steps you must take to avoid propylene glycol.

1. Read food labels

Whenever you purchase processed food, make sure you read the label correctly. Propylene glycol can also be mentioned as ‘propane-1,2-diol’ or ‘E1520′ on the food labels. So, avoid processed food and so for fresh fruits and vegetables instead.

2. Purchase chemical-free cosmetics

Many cosmetics and personal care items include propylene glycol. Body wash, mouthwash, ointments, skin treatment cream, deodorants, and even baby wipes can include this compound. Read the labels carefully and avoid using such products.

3. Opt for natural products

Opt for natural products wherever possible to avoid exposure to propylene glycol. Use homemade salad dressing and bake stuff at home. Avoid processed sauces and make them at home. You can also create your household cleaners at home.

Final thoughts

Propylene glycol is a petroleum-based chemical that is used in many products including food, cosmetics, medicines, and industrial products.

Though it is generally considered safe for use, excessive doses can lead to medical problems. It can lead to skin irritation, respiratory problems; and increase the risk of heart attack.

People with liver and kidney problems, infants and pregnant women should avoid exposure to propylene glycol. Eating fresh food, avoiding junk food and opting for natural cosmetics can lower your exposure to propylene glycol.

Propylene glycol is a synthetic food additive, an organic compound, which is usually a tasteless, odorless and colorless clear oily liquid.