Is Polypropylene Toxic to Humans?

Medically Reviewed on 3/19/2021

Polypropylene (PP) is usually considered safe for humans.
Polypropylene (PP) is usually considered safe for humans.

Polypropylene (PP) is usually considered safe for humans. It is considered the safest of all plastics; it is a robust heat-resistant plastic. Because of its high heat tolerance, it is unlikely to leach even when exposed to warm or hot water. It is approved for use with food and beverage storage. It can be re-used safely and used with hot beverages.

However, few studies have reported that it can leach on plastic additives and cause occupational asthma. It is less likely to contain fillers, plasticizers, and additives compared with many other plastics, but they may still be present. Unfortunately, without better disclosure from manufactures about the content of specific plastic materials, we can only speak about toxicity and safety in general terms.

  • Several safety organizations including the International Agency for Research on Cancer (IARC) and Occupational Safety and Health Administration (OSHA) do not find PP to be carcinogenic according to its Safety Data Sheet.
  • PP is very similar to polyethylene but has higher resistance to heat, which is why it is often used for food packaging and food storage bags and containers.

Potential health effects of PP:

Eyes:

  • Contact of powder or fines with the eye may cause mechanical irritation.
  • Contact with a hot or molten material may cause severe injury, including possible blindness.

Skin:

  • Contact of powder or fines with the skin may cause mild to more serious irritation that is increased by mechanical rubbing or if the skin is dry.
  • Contact with a hot or molten material may cause severe thermal bums.

Ingestion:

  • Although unlikely, ingestion of PP may produce mild gastrointestinal irritation and disturbances.

Inhalation:

  • Inhalation of fine particles may cause respiratory irritation.
  • Fumes produced while thermal processing may cause irritation, pulmonary edema, and a possible asthma-like response.

Although PP is relatively stable and generally considered a safer plastic for food and drink, it has also been shown to leach plastic additives. In one study, pure PP resin did not leach any endocrine-disrupting chemicals, but common food containers made with PP did leach. Leaching from plastic food containers is increased with heat, duration of contact, and acidity of the food or drink. Therefore, consider how the item is being used and how you will be exposed to it. For example, a water bottle made of PP that has only brief contact with the water is less likely to leach than a container used to store hot tomato soup.

What is polypropylene (PP)?

Polypropylene (PP) is made by combining propylene monomers (a tasteless, colorless, odorless synthetic material). It has numerous different applications such as consumer packaging material, plastic hinges, waterproofing insulation, and more. It is considered a low-toxin, heat-tolerant material. This type of plastic is used for various applications related to human consumption, including straws, yogurt containers, bottles, and even medical devices.

The advantages of PP include:

  • It is readily available and relatively inexpensive.
  • It has high flexural strength because of its semi-crystalline nature.
  • It has a relatively slippery surface.
  • It is very resistant to absorbing moisture.
  • It has good chemical resistance over a wide range of bases and acids.
  • It possesses good fatigue resistance.
  • It has good impact strength.
  • It is a good electrical insulator.

The disadvantages of PP include:

  • It has a high thermal expansion coefficient (marked increase in volume with temperature increase) that limits its high-temperature applications.
  • It is susceptible to ultraviolet (UV) degradation.
  • It has poor resistance to chlorinated solvents and aromatics.
  • It is known to be difficult to paint because it has poor bonding properties.
  • It is highly flammable.
  • It is susceptible to oxidation.

Avoiding any plastic is ideal because it not only poses risk to human health but also is harmful to the environment. However, if you must use products made with PP, the risk of exposure is probably low.

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Medically Reviewed on 3/19/2021
References
Carcinogenic Effects of Exposure to Propylene Oxide: https://www.cdc.gov/niosh/docs/89-111/default.html