Chemical profile: PROPYLENE GLYCOL (PG)

1. What is propylene glycol?

Propylene glycol is a liquid compound that absorbs water. Propylene glycol is also used to synthesize polyester, and is the base for de-icing agents.

Propylene glycol is used in the chemical, food, and pharmaceutical industries and is also used as an antifreeze. The Food and Drug Administration (FDA) has classified propylene glycol as a “generally recognized as safe” food additive.

It is used to absorb extra water and maintain moisture in medicines, cosmetics, or certain food products. It is a solvent for food colors and flavors, and in the paint and plastics industries.

Propylene glycol is also used to create artificial smoke or fog used in firefighting training and in theatrical productions. Other names for propylene glycol include 1,2-dihydroxypropane, 1,2-propanediol, methyl glycol, and trimethyl glycol. Propylene glycol is a clear, colorless liquid that evaporates weakly at room temperature. It can exist in the air as a vapor, although propylene glycol must be heated.

Propylene glycol is practically odorless and tasteless.

2. What happens when Propylene glycol is released into the environment?

Waste streams from propylene glycol production primarily impact air, water and soil.

Propylene glycol can also enter the environment through the disposal of products containing it. It is unlikely to exist in large quantities in the air.

We have very little information about what happens to propylene glycol in the air.

Small amounts released into the air are likely to degrade rapidly. If released into the air in large amounts, it will take approximately 24 to 50 hours to completely degrade. Propylene glycol is completely soluble in water and can leach into soil. It can degrade relatively rapidly (within days to a week) in water and soil.

3. How can I be exposed to propylene glycol?

Propylene glycol has been approved for use to some extent in food, cosmetic, and pharmaceutical products.

If you use food products, use cosmetics, or take medications that contain it, you will be exposed to propylene glycol, but the doses are not generally considered harmful.

People working in industries that use propylene glycol may be exposed by touching the products or inhaling the vapor mist.

The risks tend to be low,

However, Propylene glycol is used to make artificial smoke and mist for fire safety training, stage performances, and rock concerts. If used in a confined space, exposure may be more intense.

4. How does liquid propylene glycol enter and leave the human body?

Propylene glycol can enter your bloodstream if you breathe air containing mist or vapor from this compound. It can also enter your bloodstream through your skin if you come into direct contact with it and do not wash it off.

If you eat products containing propylene glycol, it can enter your body.

Exposure of the general population to propylene glycol is possible from a variety of foods, drugs, and cosmetics containing it.

Propylene glycol breaks down in the body in about 48 hours. However, human and animal studies show that repeated exposure to propylene glycol in the eyes, skin, nose, or mouth over a period of time can cause some degree of irritation to the body.

5. How can propylene glycol affect human health?

Propylene glycol can decompose at a similar rate to ethylene glycol, although it does not form harmful crystals as it decomposes.

Propylene glycol in frequent contact with the skin can sometimes cause skin irritation.

6. Are there medical tests to determine whether humans have been exposed to propylene glycol?

Propylene glycol is generally considered a safe chemical, and is not routinely tested unless specific exposure, such as to a drug or cosmetic, can be linked to adverse reactions.

Propylene glycol breaks down very quickly in the body so it is difficult to detect.

7. What recommendations has the federal government made to protect human health?

The government has developed regulations and guidelines for the use of propylene glycol.

The Food and Drug Administration (FDA) has classified propylene glycol as "generally recognized as safe," meaning it is acceptable for use in flavorings, drugs, and cosmetics, and as a direct food additive.

According to the World Health Organization, the acceptable dietary intake of propylene glycol is 25 mg of propylene glycol per kilogram (kg) of body weight.