Daily Footprint, #6 – Clothing (Sustainable Textiles, Part 2)

In part one, I took a look at some issues to consider when rating textiles from a social and environmental perspective. Here are a few remaining factors to consider, but do make a choice based on what’s most important to you and then share your information with others by writing a “green star” review (of an item of clothing or a store). So, this isn’t intended to be an authoritative guide but rather to serve as an example of the decision-making process.

Chemical Processing

Dyeing and finishing aside (I’m considering everything up to the point of raw textile here) there’s not a lot of chemical processing required for natural fibers (cotton, flax, hemp, wool) compared to synthetic or semi-synthetic fibers. However, as mentioned in part one, agricultural inputs are large for cotton (also see here) – the WHO estimates more than 3 million pesticide poisonings (20,000 deaths) occur globally each year, largely among the rural poor, but based on a three-year study on cotton growers in West African countries numbers are actually probably higher than this. Some synthetics, such as polyester, are considered cleaner to make than others but still require large petrochemical inputs – an estimated 70 million barrels of oil is used to make polyester annually. Acrylic involves more hazardous chemicals that increase the impact beyond the raw petrochemicals: a 2010 study calculates that the odds of contracting breast cancer were almost 8 times higher for women who spent 10 years working with acrylic fibers (and two-fold higher for nylon fibers). But I’m skimming over these a little (more on them later) to spend time on the increasingly popular regenerated cellulose fibers collectively known as rayon.

Rayon: Lyocell & Viscose

Viscose was developed over 120 years ago, and it involves taking cellulose from plants, sulfating it with carbon disulfide, and then regenerating the cellulose by extruding it into a bath of dilute sulfuric acid. Lyocell is made by a newer process developed in the 1980s in which cellulose from wood pulp is processed using more benign solvents. The most well-known maker of lyocell is the Austrian company Lenzing, who used a closed-loop process (in which almost all of the solvent is recycled) to make lyocell from eucalyptus wood pulp under the brand name Tencel and also Modal from beech wood.

Viscose is more common than lyocell and in particular viscose made from bamboo has being gaining popularity as an eco-friendly fabric – but then came under fire because of the solvents involved. Cellophane, the clear biodegradable cellulose-based film that has been used to wrap items like cheese and sweets until plastic took over, is also made by the viscose method. So this discussion is also relevant to deciding on products wrapped in plastic versus cellophane (for example, this cheese that I reviewed recently). The three main components used to make viscose (a.k.a. rayon) from bamboo are sodium hydroxide, carbon disulfide, and sulfuric acid. Of these, the main concern is with the carbon disulfide, since the other two are commonly used in industry and can be easily neutralized.

Carbon disulfide, in high concentrations, is explosive and causes immediate symptoms such as vomiting and difficulty breathing. So there’s little doubt that it needs to be handled with care. However, it’s naturally-occurring (a large percentage is produced by oceans, marshes, and volcanos), is rapidly metabolized, does not accumulate in food chains, doesn’t persist in water or soil since it evaporates quickly, and in air it breaks down in about 12 days. I would argue that it’s easier for companies to ignore problems that lead to long-term, cumulative effects on the workforce or environment than those with immediate acute effects. I’m not saying that carbon disulfide is wonderfully safe, but we are looking at ranking textiles based on how much harm they do, and if handled properly I don’t think it’s as much of a problem as cotton pesticides or manufacturing of acrylic. The fact that bamboo is widely acknowledged as a sustainable raw material is of course a major selling point of this material (see my Yelp review of a bamboo store)

Much of the viscose from bamboo is made by the Hebei Jigao fiber company in China. An importer from San Francisco was concerned about the company’s impact and decided to visit – she reported that although it wasn’t a closed loop facility like Lenzing, they did have a sophisticated water treatment facility. The company have posted their certifications on their site. My feeling is that viscose from bamboo does have some downsides because of the manufacturing process but that it’s a better choice than most synthetic fabrics and conventional cotton. I expect there will be improvements on processing bamboo in future.

Bob the street cat styling a woolly scarf. No relevance here really; just wanted to brighten up an otherwise sombre blog post. (Photo credit: Mathew Wilson)

Impact During Use

One of the largest impacts of clothes is cleaning them: the majority of energy use (71%) is due to tumble-drying, followed by heating water. The best ways to reduce your impact are to hang laundry to dry when possible, use efficient washing machines and a detergent that works at lower temperature. If Americans adopted these habits, even just air-dried their laundry half the time, it would be equivalent to taking 12% of American cars off roads.

Another major impact from laundering that’s just coming to light is plastic pollution. Recent research by Mark Browne at the University of California at Santa Barbara has shown that synthetic fabrics shed an alarming amount of plastic fibers – up to 1900 microthreads per item per wash. Because they are so small, the fibers can bypass wastewater plants and end up in rivers and oceans; Dr. Browne’s group sampled beaches on six continents and found that the majority of microplastic pollution consisted of synthetic fibers (mainly polyester and acrylic) – between 8 (Australia) and 120 (Portugal) fibers were detected per liter of sand. The problem goes way beyond beaches since the plastic attracts organic compounds from oceans which then accumulate in fish and other aquatic organisms and upward through the food chain.

All things considered, which textiles are best?

It has to be said that repairing or repurposing your old clothes and buying pre-owned (vintage) clothes are the best ways to go (thank you students and hipsters for helping to eliminate the stigma there!). Another good approach is to buy things that you love that will last a long time.

My personal ranking:

  1. Linen (flax) and hemp
  2. Wool and some other animal fibers (depending on practices used)
  3. Tencel and other lyocell made from sustainably harvested wood
  4. Viscose from bamboo
  5. Organic cotton
  6. Conventional cotton
  7. Recycled polyester and nylon
  8. Conventional Polyester and nylon
  9. Acrylic

Linen and hemp really stand out as the top choices, with very little downside. See my review of a hemp clothing store in Kauai for more information on this great crop that has been discouraged for mainly political reasons. Cotton from farms that practice water conservation and organic agriculture is a considerably better choice than conventional cotton. Recycled polyester is becoming very popular (polyester is made from PET, the same plastic – #1 – used to make many bottles) and it takes fewer resources to make polyester from recycled PET but my main reason for ranking it lower than cotton is to exercise caution on the microfiber pollution issue.

The top six on the list are all natural fibers (or regenerated cellulose) and can be composted at the end of their life. If fabric made from bamboo bast fibers (the same process as linen and hemp) became widely available it would share the top position. In the future, look out for textiles made from food waste fibers such as coconut fiber, banana stems and pineapple leaves.


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