Google “toxic fabrics” and a host of sites will come up, some from as far back as 1993. Generally they list a number of synthetic fabrics (acrylic, nylon, polyester) along with rayon (which is made from chemically processed wood pulp) and make the case that all are bad because they are made from scary chemicals. Obviously, natural fibers such as cotton, hemp, wool, and linen are the way to go. Those are made from plants and sheep, not coal and petroleum derivatives.
The truth is more complicated than this. Your clothing is never made solely out of just cotton or polyester. Every single fabric has some form of processing. It may be preshunk cotton, or superwash merino. It may be bleached. It’s almost always dyed. And nowadays clothing comes in all kinds of high-tech variations: UV protective, bug repellant, wrinkle-free, stain resistant, antimicrobial, and so on. Even pure cotton can be grown with pesticides.
These chemicals pose a myriad of concerns for the environment, both in the place of manufacture and due to chemicals released through washing. But what about the safety to the wearer?
The Basics: What Are Fabrics Made From?
If you look in your closet, you’ll likely find a number of different natural and synthetic fibers. Over 60 percent of global fiber consumption is comprised of petroleum based synthetic fibers, although some may be used for textiles other than clothing (like rugs or rope). Comparatively, cotton makes up nearly a quarter of textile consumption, with wool making up about 1 percent, and other natural fibers (hemp, linen, etc) accounting for 5 percent. The remaining 6.6 percent are wood-based cellulose fibers (e.g. rayon).
Natural fibers come from either plants or animals. Plants used for clothing include cotton, hemp and flax. Animal fibers are more diverse, even if some, such as yak, remain uncommon. However, sheep are not the only animals who can provide high-quality fiber: alpacas, goats (cashmere and mohair), rabbits (angora), yaks, camels, llamas, and even the wild alpaca relative, the vicuña, provide fiber used for clothing. Silk is also a natural fiber, made from the cocoons of the mulberry silkworm. Other animal products used in clothing are hides (leather), feathers (down) and fur.
While humans have used natural fibers for millennia, rayon, which is made from wood fibers with synthetic processing, was invented in 1894, and the first fully synthetic fiber, nylon, was invented in the 1930s. Other wood-based fibers produced with synthetic processing include modal and bamboo. Fully synthetic fibers, generally made from petroleum or coal products, are acrylic, polyester and spandex.
Toxicology research into clothing focuses less on the fibers themselves and more on the chemicals used in processing the fibers. Even a simple cotton T-shirt requires numerous chemicals to bring it to market. The question for consumers is not only how safe are the chemicals used, but what are you willing to sacrifice and how much are you willing to spend in order to get the chemicals out of your closet?
Your clothes do not contain only cotton or rayon or polyester. They are also bleached and dyed. Dyeing also requires the use of a “mordant,” a chemical that helps the dye adhere to the clothing. While natural dyes can be used along with a mordant like alum or cream of tartar, unless your clothing says otherwise, you can be almost certain natural dyes were not used.
Three different dye chemicals (or groups of chemicals) are of most concern. Azo dyes can release chemicals called aromatic amines when you wear them, and they can be absorbed into your body. There are hundreds of different azo dyes, and a large number of them can release aromatic amines. Some of these aromatic amines are known to be toxic (or as scientists put it, they are of “toxicological concern”), and others have never been assessed for toxicity. The main concerns are that these chemicals can cause cancer, and they also may be allergens. A 2014 study found that 17 percent of clothing samples contained aromatic amines “of high toxicological concern,” including several that had them in higher levels than legally allowed in the European Union.
Second, quinoline is a chemical used in dying textiles that causes concern. According to another 2014 study, even though no human studies on their carcinogenicity are available, tests involving acute exposure of mice have demonstrated “quinoline and some of its methylated isomers to induce liver cancer.” That study found that quinoline was found in polyester clothing more than it was found in clothing made from other fibers. One study labeled quinoline a potential human carcinogen, and reiterated the correlation of quinoline with polyester.
Last, heavy metals are a concern as well. They can be used in clothing in dyes, mordants, flame retardants, antimicrobials, water repellants, or in the manufacturing of synthetic fabrics. A 2015 study found high levels of chromium in polyamide dark clothes, high levels of antimony in polyester clothes, and high levels of cotton in some green cotton fabrics. Overall, it found that all of the metals were well below the levels considered unsafe. However, this study had a very small sample size so its findings may not be conclusive.