What are the uses of propylene glycol?
Propylene glycol includes two isomers: 1,2-propanediol and 1,3-propanediol. The latter is mainly used as a solvent in industry and production. Therefore, when people refer to propylene glycol in everyday life, they are usually referring to 1,2-propanediol.
Propylene glycol is an organic compound that is an almost odorless, viscous liquid at room temperature. It is chemically stable, has some hygroscopic properties, and has very low toxicity and irritation.
Propylene glycol has a wide range of uses in industry and daily life:
It is miscible with water and can dissolve organic matter, so it is widely used as a solvent in the chemical industry;
In cosmetics, soaps, and toothpaste, propylene glycol is often used as a wetting agent, humectant, and antifreeze agent;
It also has some applications in resin synthesis and pharmaceuticals.
Can propylene glycol be added to food?
China has issued detailed national food safety standard GB2760-2014, “Standard for the Use of Food Additives,” regarding food additives.
This standard stipulates that propylene glycol can be used as a synthetic flavoring agent in food, primarily acting as a stabilizer, coagulant, anti-caking agent, defoamer, emulsifier, humectant, and thickener.
However, the national standard also specifies that the use of propylene glycol is limited to raw wet noodle products (noodles, dumpling wrappers, wonton wrappers, etc.), pastries (such as Chinese pastries, Western pastries, mooncakes, etc.), and edible decorations for pastries.
In raw wet noodle products, the amount of propylene glycol added must not exceed 1.5 g/kg; in pastries and their edible decorations, the maximum amount of propylene glycol added is 3 g/kg.
Therefore, propylene glycol, as a food additive with very low toxicity and permitted by the state, is allowed to be added to some foods as long as the content does not exceed the limit. However, the national standard does not permit the addition of propylene glycol to milk.
What are the dangers of ingesting propylene glycol?
Propylene glycol, a legally permitted food additive in China, poses no health risks when consumed in compliant foods. The Codex Alimentarius Commission (JECFA) has set the acceptable daily intake (ADI) for propylene glycol at 0-25 mg/kg body weight. This means that for a 60 kg adult, a daily intake of 1.5 grams of propylene glycol is within the safe range.
Regarding the potential harm of propylene glycol to the human body, it is necessary to comprehensively consider the propylene glycol content in food and the frequency of consumption. A single large intake of propylene glycol may cause kidney damage, while long-term consumption of food with excessive propylene glycol levels may lead to its accumulation in the kidneys, harming human health.
In which industries is propylene glycol used in daily life?
Besides its use as a food additive, propylene glycol can be found in many aspects of daily life, such as in cosmetics, skincare products, and toothpaste.
The main functions of propylene glycol are as follows:
- Moisturizer: Similar to glycerin, propylene glycol has a certain water-absorbing and water-retaining capacity. Compared with glycerin, propylene glycol’s moisturizing properties are gentler and more moderate. Therefore, propylene glycol is often added to cosmetics and skin care products as a moisturizer to enhance their moisturizing performance.
- Antifreeze agent: Adding propylene glycol to cosmetics and skin care products can effectively lower the freezing point of liquids, making them less likely to freeze at low temperatures, thus facilitating the preservation and use of cosmetics and skin care products in winter.
- Lubricant: Propylene glycol has strong penetrating properties and good dissolving and dispersing properties for organic matter. When added to cosmetics and skin care products, it can help other ingredients to be evenly dispersed on the skin surface and promote skin absorption. In addition, in toothpaste, propylene glycol can be used in combination with glycerin and sorbitol as a humectant; in hair dye, propylene glycol can also help the dye substances disperse better on the hair, while also playing a moisturizing role.
In conclusion, propylene glycol has a wide range of applications in daily life, and it is also permitted as a food additive in certain specific foods. Consuming these compliant foods normally does not pose a health hazard. In fact, approximately 45% of ingested propylene glycol is excreted unchanged through the kidneys, while the remainder is metabolized in the body into lactic acid and pyruvic acid (normal byproducts of human energy metabolism). Therefore, unlike heavy metals, it does not accumulate easily. Only in cases of “extremely high doses” or “impaired liver and kidney function” is there a particular concern about the potential for toxic accumulation.
