I was helping a reader evaluate a product made from polyethylene terephthalate and thought it would be helpful to share the information because it can be confusing.  This material has more than one chemical name as well as many brand names.  Also, surprisingly, it is not a phthalate!

Debra Lynn Dadd wrote the following article on zerotoxics.com.

POLYESTER is a category of polymers that have a specific structure. As a material, it usually refers to a the type of polyester called POLYETHYLENE TEREPHTHALATE (PET)

It is the most common thermoplastic polymer resin of the polyester family and is used to make

• fibers for clothing (where it is called “polyester” or Dacron)
• recyclable containers for liquids and foods (where it is called PET or PETE)
• film for food packaging and space blankets (where it is called MPET or Mylar)

Polyester and polyethylene terephthalates are one and the same.

Polyester is the third most-produced polymer in the world, after polyethylene (PS) and polypropylene (pp).

GOTS-Approved Polyester & Polyethylene Terephthalate

Global Organic Textile Standard (GOTS) approves certain non-agricultural materials for use in making GOTS-certified products that are primarily made from organic agricultural materials. These “approved” materials must meet the portion of their standard that prohibits a whole list of toxic chemicals. “GOTS-Approved Polyester” and “GOTS-Approved Polyethylene Terephthalate”  are polyester and polyethylene terephthalate, respectively, that qualifies to be used in GOTS-certified organic products because it does not contain any of their prohibited chemicals.

This makes polyester and polyethylne terephthalate two of the few plastics approved by GOTS for the making of the incidental “accessory” pieces needed to construct a quality product.

NOTE: About 85% of polyesters contain antimony, which is not allowed by GOTS. GOTS-certified polyester is tested to ensure no antimony is present in the polyester approved by GOTS. This does not mean that all polyester is approved by GOTS, only polyester that is free of antimony and other toxic residues.

Common Misconceptions

There are some common misconceptions about polyethylene terephthalate.

1. Polyethylene terephthalate contains ZERO polyethylene.

Plastics are made of basic units called “monomers.”

The monomer for PET is ethylene terephthalate. PET is commonly recycled, and has the number 1 as its recycling symbol.

The monomer for polyethylene is ethylene. PE is also commonly recycled and has the number 4 as it’s recycling symbol.

These are two different plastics.

2. Polyethylene terephthalate contains ZERO phthalates.

PET and PETE are acronyms for “polyethylene terephthalate.” It’s logic to think that “terephthalate” contains “phthalates.” But the toxic “phthalates” that leach out of plastics are “orthophthalates,” which is a completely different type of chemical than “terephthalate.”

Health Effects

PET has been approved as safe by the FDA and the International Life Sciences Institute (ILSI). In 1994, ILSI stated that “PET polymer has a long history of safe consumer use, which is supported by human experience and numerous toxicity studies.”

I also researched to see if there was any release of chemical gasses from PET into the air. (this is called “outgassing”).

NASA has a website called Outgassing Data for Selecting Spacecraft Materials Online where you can look up all kinds of materials they have assessed because they need to choose materials for spaceships that do not outgas. They found that PET needed zero curing time to be used in a spaceship. So if you are designing a spaceship or some other small area, PET would be a good choice.

All that said, in recent years there have been some concerns about specific uses of polyether and PET.

Problems with leaching from water bottles are the most widely publicized problem. Most commonly discussed is leaching of antimony, a metalloid element that is used as a catalyst in the making of PET. After manufacturing, a detectable amount of antimony can be found on the surface of the PET. While this can be removed with washing, antimony within the PET can migrate into the water in the bottle, or any other liquid contained in a PET bottle. According to the World Health Organization (WHO), the health risk of the resulting low concentrations is negligible (1% of the “tolerable daily intake).

Antimony is also present in polyester fibers, but again, will you actually be exposed to it and will it cause a health effect? This well-reserched post says no: O ECOTEXTILES: WIll the antimony in polyester fabric hurt me?

There have also been reports of leaching of aldehydes from PET bottles, enough to give an off-taste to bottled water. Even extremely low concentrations (10–20 parts per billion in the water) of acetaldehyde can produce an off-taste. Whether or not this poses a health risk is undetermined.