The Chemical Composition Of Polyester – Is It Safe?
Written by Irina Webb
Light, versatile, compact, easy to wash, fast to dry, hard to wrinkle – polyester makes travelling a dream. Indeed, you throw a couple of dresses, a few blouses, two pairs of pants in your travel bag and you are good to go! You don’t have to worry about finding an iron or “showing off” sweat spots on your clothes – the polyester material has taken care of that. No wonder polyester is one of the most popular textiles in the world. According to the latest statistics, in 2022, global production of polyester fibers equaled 63.3 million metric tons, amounting to more than half of the world’s total fiber production.
Standing out among synthetic fibers, polyester is extensively used in clothing, home furnishings, even soft drinks bottles, and various industrial applications. Hence, its widespread use makes it essential to understand its chemical composition. This knowledge will help you make informed decisions about whether polyester fabrics are safe to use in your daily life. Today, I am dedicating this post to exploring the chemical composition of polyester. Read on to find out why I stopped using polyester leggings!
The Importance Of Knowing The Chemical Composition Of Polyester
To begin with, understanding the chemical composition of polyester is crucial for several reasons. For one, it will help you comprehend how this common material is produced and what goes into making it. Plus, it will allow you to evaluate the potential health and environmental impacts associated with its use. In this post, you can expect a detailed breakdown of the chemicals involved in polyester production and their effects.
For your information, the most common polyesters include:
- PET
- PCDT, and
- plant-based polyester.
First, PET, or polyethylene terephthalate, is a clear, strong, and lightweight plastic. It is widely used for packaging foods and beverages, especially convenience-sized soft drinks, juices, and water. Typically, single-serving and 2-liter bottles of carbonated soft drinks and water sold in the United States are made from PET (source).
Second, PCDT, or poly-1,4-cyclohexylene-dimethylene terephthalate, is more elastic and durable than PET, and is also resistant to pilling (forming small fluff balls on textiles). Because of its properties, it is common in heavy-duty applications, like upholstery and curtains (source).
Third, plant-based polyester originates from sugar cane and other plant sources. It works for clothing, sports apparel, student uniforms, and automotive interior materials (source).
Additionally, there is cotton polyester, or polycotton, that combines cotton and polyester fibers. Normally, the ratio is 65% polyester and 35% cotton, but it can vary depending on the purpose of the fabric. Cotton polyester features improved shrinkage, durability, and wrinkling properties, which makes it great for long-term use in outdoor applications (source and source).
What Is Polyester Made Of?
Well, in layman’s terms, polyester is made from petroleum.
In chemical terms, polyester is a polymer composed of repeat units of a chemical compound within the ester functional group. The repeat unit of polyester is ethylene terephthalate. Most synthetic and some plant-based polyester fibers are made from ethylene, a constituent of petroleum that can also be derived from other sources (source).
Let’s delve into the specific chemicals involved in the production of polyester.
Polyester Composition
Technically, the polyester production process involves two primary raw materials: terephthalic acid (aka benzene-1,4-dicarboxylic acid) and ethylene glycol (aka ethane-1,2-diol). A chemical reaction between these two compounds creates the polymer chains that form polyethylene terephthalate (PET) (source).
However, there are other chemicals that manufacturers add to the formulation during the manufacturing process. For example, antimony serves as a catalyst and flame retardant. Plus, there are anti-static agents, wrinkle-resistant agents, dyeing agents, and possibly others.
Terephthalic Acid
For starters, terephthalic acid is a type of dicarboxylic acid that is a key ingredient in polyester production. It reacts with ethylene glycol to form the polymer chains through ester linkage. This reaction involves forming the ester bond, which is crucial for creating the durable polyester fibers used in various applications.
To clarify, dicarboxylic acids have a wide range of direct or indirect industrial applications. Thus, dicarboxylic acids are used in food as well as in the preparation of such copolymers as polyamides and polyesters. Specifically, for polyester, they use glutaric acid which is also used in the synthesis of pharmaceuticals and surfactant compounds. Further, adipic acid is used in the production of nylon as well as a gelling aid and as a leavening and buffering agent. And in the food and beverage industry, they use succinic acid as an acidity regulator (source).
Ethylene Glycol
Next, ethylene glycol in polyester production serves as a reactant with terephthalic acid to form polyethylene terephthalate (PET). Ethylene glycol is a type of alcohol with two hydroxyl groups that contributes to the polymer’s structural integrity. The European Chemicals Agency (ECHA) states that “this substance may cause damage to organs through prolonged or repeated exposure.”
Antimony
Further, manufacturers can use antimony as a catalyst and a flame retardant in the production of polyethylene terephthalate (PET). The European Chemicals Agency (ECHA) defines antimony as toxic to reproduction.
And antimony trioxide, a compound produced from antimony, is on the CA Proposition 65 list as a substance known to the State of California that may increase the risk of cancer. (Learn more about antimony trioxide and other flame retardants in my blog post about whether organic mattresses are worth it.)
This is particularly disturbing because, apparently, antimony can get on your skin from polyester clothes you are wearing. Indeed, using standard artificial sweat solutions, the scientists in this study discovered that antimony released from polyester textile samples designed to be in contact with human skin.
Interestingly enough, several years ago, I underwent heavy metal testing as part of my autoimmune diseases recovery process. Among other things, the test showed high levels of antimony in my body. It was confusing news because by that time I had introduced many healthy changes in my life, including sleeping on an organic mattress and using a water filter. So, together with my functional doctor, I went over all potential sources of antimony in my life. As a result, we found only one possible source of antimony – my polyester leggings that I used for my daily exercise and as my home wear. Albeit an assumption (because I didn’t actually test my leggings for antimony), I quit wearing polyester athletic wear. Instead, I switched over to organic cotton wear from Pact (first-time buyers get 20% off with this link).
Antistatic Agents
Antistatic agents are chemicals that help reduce or eliminate static electricity buildup in polyester fabrics. Indeed, static electricity can cause sparks, damage to electronics, and it attracts dust and dirt. Because polyester is not a good conductor of electricity, it can produce high static charges. To avoid this, as well as any issues during processing, manufacturers use antistatic agents (source).
Wrinkle-Resistant Agents
Some wrinkle-resistant chemicals include formaldehyde, Teflon, and PFAS.
First, formaldehyde is a colorless, flammable, and strong-smelling chemical that can make clothing wrinkle-free and help dyes stick. Formaldehyde in products also functions as a preservative. Exposure to formaldehyde can cause skin irritation, allergic reactions, asthma flare-ups, nausea, and dermatitis. Long-term exposure to formaldehyde fumes may also cause respiratory problems and cancer. Just as antimony trioxide, formaldehyde is on the CA Proposition 65 list. It may be a surprise for you to learn that formaldehyde is one of the hidden ingredients in baby wipes.
Next, Teflon is a trademark for polytetrafluoroethylene (PTFE) that may contain perfluorooctanoic acid (PFOA) and other undisclosed materials that have lots of health concerns. As a matter of fact, it is one of the potentially toxic chemicals in makeup, too.
Last, PFAS, aka “forever chemicals,” find their way into many everyday clothing items, including athletic clothes, protective outerwear, and school and professional uniforms. However, there is no requirement for manufacturers to disclose their use of PFAS. You can learn more about PFAS and their toxicity in my blog post about non-toxic baking sheets.
Dyeing Agents
They use disperse dyes and boiling water to color polyester fabrics. Disperse dyes can be toxic to humans and aquatic organisms. Some disperse dyes can cause allergic reactions, especially when used in close-fitting synthetic clothing. And some disperse dyes have a link to cancer (e.g., disperse blue 1).
By the way, check out this period underwear that uses reactive dyes as opposed to disperse dyes. It also fared well in testing for fluorine, a proxy for PFAS (i.e., if the test is positive for fluorine, it is a strong indicator that there are PFAS in the product).
Is Polyester Bad For You?
On the one hand, the safety degree of polyester fabrics largely depends on their usage and application. On the other hand, based on what we have learned about the production process and the chemicals involved, namely terephthalic acid, ethylene glycol, and antimony, it’s hard to call polyester the safest choice, both health-wise and environment-wise.
Indeed, some people may experience sensitivities to synthetic fibers manifested in skin irritation or allergies, not to mention other potential health risks caused by the chemicals in polyester formulation.
Additionally, polyester production raises environmental concerns due to its petroleum-based origins. Factors affecting the chemical composition of polyester include the quality of the raw materials, the specific production processes, and the presence of any additives or finishes applied to the final products. Although polyester is durable and versatile, it is not as environmentally friendly as natural fibers.
Moreover, there is an issue with microplastics contamination. Admittedly, textiles are a large source of microplastics, accounting for 34.8% of global microplastic pollution (source). When you wash synthetic fibers such as polyester or acrylic, microfibers detach from your clothes and go into the wastewater. Being very small, many of them pass through filtration processes at sewage treatment facilities and make their way into the rivers and seas. The fish eat microplastics, and then we eat the fish with microplastics. It’s cyclic. By the way, exposure to microplastics can cause inflammation, endocrine disruption, immunity, and metabolism disorders, as well as other ailments (source).
Summary: Is Polyester Safe?
Given Its Chemical Composition, Chemical Additives, Environmental Impact, And Potential Health Concerns, I Do Not Consider Polyester Safe.
Overall, polyester has multiple applications, including clothing and home furnishings. While polyester remains a staple in the textile industry due to its durability and versatility, it is essential to consider both the health and environmental implications of its use. The environmental impact of polyester production, involving the use of petroleum-based chemicals, is a significant concern. Therefore, opting for natural fibers can be a more sustainable and healthy choice.
My husband wears polyester clothes occasionally. For the most part, he opts for cotton, but on days when he feels the necessity to wear something polyester (typically a golf shirt or a dress shirt), he first puts on an organic cotton undershirt made by Pact (first-time buyers get 20% off with this link). He claims they are very comfortable, and he usually forgets he’s wearing an undershirt under his polyester shirt.
Ultimately, please know that it is impossible to avoid all the toxins around you. So, try to manage your stress (which is the biggest toxin) by doing what you can and what is in your control. Contact me if you need help with that.
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