Propylene glycol is a versatile and widely used chemical compound that is found in a variety of consumer products, including food, cosmetics, and pharmaceuticals. It is a clear, odorless, and colorless liquid that is soluble in water and has a slightly sweet taste. 

Propylene glycol is valued for its ability to act as a solvent, stabilizer, and humectant, and it is commonly used to enhance the texture, flavor, and shelf-life of products. In recent years, propylene glycol has also gained attention for its use in e-cigarettes, where it is used as a base for the liquid that is heated and inhaled as a vapor. 

This blog post will explore the uses, benefits, and safety of propylene glycol in various industries and products, including e-cigarettes. We will also discuss its benefits in food, pharmaceuticals, cosmetics, and industrial applications.

By the end of this blog post, readers will have a better understanding of propylene glycol, and the implications for industry and consumers. 

Importance of propylene glycol in various industries 

The importance of propylene glycol lies in its ability to act as a versatile solvent, carrier, stabilizer, and humectant in a wide range of industries and products. Its unique properties make it an essential ingredient in many consumer products and industrial applications.

Uses of Propylene Glycol 

Propylene glycol (PG) is a versatile chemical compound that is widely used in different industries due to its unique properties. Here is an explanation of the uses of propylene glycol in various industries:

A. Food industry 

• Sweetener and flavor carrier - Propylene glycol is used as a sweetener in various food products such as soft drinks, baked goods, and confectionery. It is also used as a flavor carrier in these products to enhance their taste.

• Moisture retention agent - Propylene glycol is an effective moisture retention agent that is used to keep food products from drying out, thereby extending their shelf life. 

B. Pharmaceutical industry 

• Solvent and stabilizer - Propylene glycol is used as a solvent in the pharmaceutical industry for various drugs and medicines. It is also used as a stabilizer for these products, preventing them from breaking down or separating.

• Excipient and carrier - Propylene glycol is used as an excipient, which means it is used as a filler or binder in tablets and capsules. It is also used as a carrier for inhalable medications such as asthma inhalers.

C. Cosmetics and personal care products 

• Humectant and emulsifier - Propylene glycol is used as a humectant in cosmetics and personal care products, which means it helps to retain moisture in the skin. It is also used as an emulsifier, which helps to mix water and oil-based ingredients.

• Solvent and viscosity regulator - Propylene glycol is an effective solvent that is used to dissolve ingredients in personal care products. It is also used as a viscosity regulator, which means it helps to control the thickness or consistency of the product.

Benefits of Propylene Glycol 

A. Food industry 

• Safe for consumption - Propylene glycol is recognized as safe for consumption by the U.S. Food and Drug Administration (FDA). It has been used in the food industry for decades and is considered safe for human consumption.

• Enhances flavor and texture - Propylene glycol is used as a flavor carrier and sweetener in food products. It enhances the flavor and texture of the food products without altering their taste.

B. Pharmaceutical industry 

• Improves drug delivery - Propylene glycol is used in pharmaceutical products as a solvent and stabilizer. It helps to improve the solubility of the drugs and increase their absorption rate, thereby improving their delivery.

• Increases shelf-life of products - Propylene glycol is a highly effective preservative that can extend the shelf life of pharmaceutical products. It prevents bacterial growth and degradation of the drugs, thereby ensuring their quality and efficacy.

C. Cosmetics and personal care products 

• Hydrates and softens the skin - Propylene glycol is a highly effective humectant that can help to hydrate and soften the skin. It helps to retain moisture in the skin, thereby preventing dryness and cracking.

• Enhances the texture and stability of products - Propylene glycol is a versatile ingredient that can help to enhance the texture and stability of cosmetics and personal care products. It can help to thicken or thin the products, and it can also help to prevent the separation of the ingredients.

Safety of Propylene Glycol 

Propylene glycol (PG) is generally considered safe for use in various applications. However, it is important to understand its potential toxicity and health concerns, regulations and safety standards, as well as the associated risks and precautions.

A. Toxicity and health concerns 

• Acute toxicity and exposure limits - Propylene glycol has low acute toxicity and is not known to cause any significant health problems. The Occupational Safety and Health Administration (OSHA) has set the permissible exposure limit for propylene glycol at 50 parts per million (ppm) over an 8-hour workday.

• Long-term exposure and health effects - Long-term exposure to propylene glycol is known to cause any significant health problems like irritation to the eyes, nose, and throat, and may also cause skin irritation and allergic reactions in some people. However, some studies have suggested the use of propylene glycol in moderation is safe. 

B. Regulations and safety standards 

• FDA and EPA regulations - Propylene glycol is recognized as safe for use in food, pharmaceuticals, and cosmetics by the U.S. Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA). The FDA has set a maximum allowable limit of 5% propylene glycol in food products.

• International safety standards - Propylene glycol is also approved for use in various countries around the world. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) and the European Food Safety Authority (EFSA) have also determined that propylene glycol is safe for use in food products.

C. Risks and precautions 

Handling and storage precautions - Propylene glycol should be handled and stored in accordance with the manufacturer's instructions. It should be kept in a cool, dry place, and should be kept away from heat and sources of ignition. It should also be kept out of reach of children.

Potential hazards and safety measures - Propylene glycol may pose a fire or explosion hazard if exposed to high temperatures or sources of ignition. Safety measures, such as the use of protective clothing and equipment, should be taken when handling and using propylene glycol. In case of accidental ingestion, exposure, or inhalation, medical attention should be sought immediately.

Studies on Propylene Glycol 

"A review of the safety of propylene glycol in food, cosmetics and medicines" (2018): This review assesses the safety of propylene glycol in various consumer products, finding that it is generally considered safe for use in the concentrations typically found in these products.

"Toxicological evaluation of glycerol and propylene glycol in aerosol generated by electronic cigarettes" (2018): This study evaluates the toxicological effects of glycerol and propylene glycol in e-cigarette aerosols, finding that they are generally safe for inhalation.

World Health Organization on use of Propylene Glycol

The World Health Organization (WHO) has recognized propylene glycol as safe for use in food, pharmaceuticals, and cosmetics. WHO has established an acceptable daily intake (ADI) of propylene glycol of 25 mg per kg of body weight. This means that a person weighing 60 kg can safely consume up to 1500 mg of propylene glycol per day without any significant health risks.

WHO also notes that the inhalation of propylene glycol through vaping has not been extensively studied, and the potential risks associated with it are not yet fully understood. WHO recommends that further research be conducted to determine the safety of propylene glycol in vaping and other forms of inhalation. In addition, WHO stresses the importance of regulating the quality and safety of e-cigarette products.

Propylene Glycol in E-cigarettes

Propylene glycol (PG) is a common ingredient in e-cigarettes or vapes, used to create the vapor that is inhaled by the user. It is added to the e-liquid along with other ingredients like vegetable glycerin, nicotine, and flavorings. PG acts as a humectant, helping to keep the e-liquid from drying out and delivering a smooth hit to the user. 

Function and Purpose of Propylene Glycol in E-cigarettes

Propylene glycol (PG) is a common ingredient found in e-cigarettes, serving multiple functions in the device's operation. 

In e-cigarettes, PG serves as a solvent and carrier for nicotine and other flavorings. It is used to create the vapor that is inhaled by the user. PG has a low viscosity and low boiling point, allowing it to easily vaporize when heated by the e-cigarette's heating element. This vaporization process creates a cloud of aerosol that is inhaled and exhaled by the user.

PG is also used in e-cigarettes to enhance flavor and vapor production. PG has a slight sweetness to it, which can enhance the taste of the e-liquid. It also produces a thin vapor, which some users prefer as it more closely resembles the sensation of smoking traditional cigarettes.

The Role of Propylene Glycol in E-cigarettes

A. PG as a solvent and carrier of nicotine

Propylene glycol (PG) is used in e-cigarettes as a solvent to dissolve and carry nicotine and other flavorings. PG has a high boiling point, and low toxicity, and is considered to be an effective carrier of nicotine, making it an ideal ingredient for e-cigarette liquids. PG is also a viscous liquid, which can help to prevent leakage of e-cigarette liquid from the device.

B. Effect of PG on flavor and vapor production

PG can affect the flavor and vapor production of e-cigarettes. It has a slightly sweet taste, which can enhance the flavor of the e-liquid. PG also produces a thin vapor that some users prefer, as it more closely resembles the sensation of smoking traditional cigarettes. 

C. Potential health risks and precautions to take with PG use in e-cigarettes

While PG is generally recognized as safe for use in food and cosmetics, its use in e-cigarettes has raised concerns regarding potential health risks. However, there is no as such research direct us towards the understanding of heath issues by using e-cigarettes. It can also vary depending on a number of factors such as the individual user's health status, the frequency and duration of use.

As per a few expert comments, inhalation of PG vapor in a regulated or moderate way has no side effects on health. However, to minimize the potential risks that could be associated with PG use in e-cigarettes, users should consider the following precautions:

1. Choose high-quality e-cigarette liquids from reputable manufacturers.
2. Practice good e-cigarette hygiene, such as regularly cleaning the device and avoiding sharing e-cigarettes with others.
3. Use of e-cigarettes in moderation. 
4. Read and follow the manufacturer's instructions for the safe use of e-cigarettes.

Health Concerns That Could Be Associated with Propylene Glycol in E-cigarettes

Effects of inhaling PG vapor are not well understood. While some studies suggest that PG is generally safe for use in food and cosmetics, the effects of inhaling PG vapor on a regular basis are still unknown. More research is needed to fully understand the long-term effects of inhaling PG vapor. However, inhalation of PG vapor in regulated or moderate way has no side effects on health.

Vegetable Glycerin:- Alternatives to Propylene Glycol in E-cigarettes

What is Vegetable Glycerin?

Vegetable glycerin (VG) is a clear, odorless liquid that is derived from vegetable oils such as coconut or palm oil. It is commonly used in food, cosmetics, and pharmaceutical products due to its non-toxic and non-irritating properties.

Use of Vegetable Glycerin in e-cigarettes

VG is used as an alternative to propylene glycol (PG) in e-cigarettes. Like PG, VG is used as a solvent and carrier for nicotine and flavorings in e-cigarette liquids. VG is also known to produce thicker vapor clouds compared to PG, making it a popular ingredient in e-liquids for cloud chasing enthusiasts.

Comparison of VG (Vegetable Glycerin) and PG (Propylene Glycol)

VG and PG have some similarities in their use in e-cigarettes. Both are commonly used as solvents and carriers for nicotine and flavorings in e-liquids. However, there are some differences between the two:

• Vapor production: VG produces thicker vapor clouds compared to PG, which some users may prefer.

• Throat hit: PG is known to produce a stronger throat hit compared to VG, which some users may prefer.

• Allergies: Some individuals may be allergic to PG and experience allergic reactions after exposure. VG is generally considered to be non-irritating and non-toxic, making it a safer option for individuals with sensitivities.

• Sweetness: VG has a slightly sweet taste, which can impact the flavor of e-liquids. PG has a less noticeable taste.

Overall, while both VG and PG are commonly used in e-cigarettes, some individuals may prefer one over the other based on their personal preferences or sensitivities. 

Conclusion

Propylene glycol is a versatile substance that finds its applications in various industries such as cosmetics, pharmaceuticals, and food. It serves as a solvent, a humectant, and a preservative. 

Propylene glycol is generally recognized as safe by the FDA and has a low risk of causing harm when used appropriately. However, it is essential to exercise caution when using it in high doses or for prolonged periods, as it may lead to mild side effects like skin irritation, headaches, or allergic reactions. 

With its appropriate use, Propylene glycol can provide benefits to various products without compromising safety.

FAQ - 

What is propylene glycol and what is it used for?

Propylene glycol is a colorless, odorless, and slightly viscous organic compound that is commonly used as a solvent, humectant, and preservative in a variety of industries. It is used in food and beverage processing, cosmetics and personal care products, pharmaceuticals, and antifreeze and deicing solutions, among other applications.

Is propylene glycol safe to consume?

Propylene glycol is generally recognized as safe (GRAS) by the U.S. Food and Drug Administration (FDA) and has been approved for use in food and beverage products as a direct additive. 

Can propylene glycol be harmful if ingested in large quantities?

While propylene glycol is generally considered safe for consumption, ingesting large quantities can be harmful. Ingesting high doses of propylene glycol can cause symptoms such as nausea, vomiting, abdominal pain, and diarrhea. 

Is propylene glycol safe for use in cosmetics and personal care products?

Propylene glycol is widely used in cosmetics and personal care products as a moisturizer and emulsifier. The Cosmetic Ingredient Review (CIR) Expert Panel has evaluated the safety of propylene glycol in cosmetics and concluded that it is safe for use in concentrations up to 50%. 

What are propylene glycol used for?

Often used as a way to absorb moisture in certain pharmaceutical or cosmetic items. Its solvents are useful for coloring and flavors in foods, paints, and the plastics industries. Propylene glycol has also been used to make artificial fumes and fogs for fire protection courses and theatrical productions.

Is vaping industry regulated in Australia?

Yes, the vaping industry in Australia is regulated, with e-cigarettes and nicotine-containing e-liquids considered to be prescription-only medicines. The sale, supply, and possession of nicotine-containing e-cigarettes is regulated by the Therapeutic Goods Administration (TGA) and varies by state and territory.

Is propylene glycol safe for use in e-cigarettes?

Propylene glycol has been used safely in a variety of consumer products, including food and pharmaceuticals, for many years. While there is ongoing research into the long-term effects of inhaling propylene glycol when vaping, current evidence suggests that it is a safe ingredient when used as directed.

Can propylene glycol cause allergic reactions when used in e-cigarettes?

Some people may be sensitive or allergic to propylene glycol, which can cause symptoms such as skin irritation, hives, or difficulty breathing. However, allergic reactions to propylene glycol are rare, and most e-cigarette users do not experience any adverse effects from using products containing propylene glycol.

How does propylene glycol compare to vegetable glycerin as an ingredient in e-cigarettes?

Vegetable glycerin is another common ingredient in e-cigarettes, where it is used as an alternative to propylene glycol or in combination with it. While propylene glycol is thinner and produces less visible vapor than vegetable glycerin, it has a slightly sweeter taste and can provide a stronger throat hit when vaping.