Denim can harm you and the planet. It’s time to go plant-based.

Ten years ago, 52-year-old Karen Baker began paying close attention to the labels of the denim jeans she purchased. She’d noticed that those dyed using synthetic indigo made her skin itch. The darker the denim was, the worse her itch became, so Baker decided to forgo wearing jeans all together.

Baker returned to wearing denim jeans a few years later. But finding denims with the right kind of dye that wouldn’t irritate her skin would cost her twice as much as she was spending before, especially if she purchased more popular brands. Eventually, her negative experiences with synthetic indigo prompted Baker to learn how to dye fabrics using organic and natural indigo.

“I couldn’t imagine my hands being in a chemical,” Baker says. “Just imagine how the skin would react in the long term if synthetic indigo continued to enter the body in the long run.”

Like Baker, many consumers of denim have for years raised their concerns about the toxicity of the denim industry, owing to the synthetic indigo it uses. In August 2019, German women’s magazine, Öko-Tes, tested one pair of jeans each from 21 different textile companies and detected the presence of aniline — a key ingredient in the production of indigo dye — in more than half of the pairs. 

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Aniline, which derives its name from the Spanish word for indigo, añil, is known to be acutely toxic when inhaled, ingested or absorbed through the skin. A health study by the Agency for Toxic Substances and Disease Registry revealed that the substance damages hemoglobin, stopping the red blood cell protein from transporting oxygen around the body — a condition known as methemoglobinemia. The study also pointed to other health effects such as dizziness, headaches and irregular heartbeat, resulting from long-term exposure to the substance. Direct contact with aniline could also lead to skin irritation according to the study, just as in Baker’s case.

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The effects of synthetic indigo are not just affecting us. Synthesizing indigo requires a number of toxic chemicals, including cyanide and formaldehyde, as does the process of dyeing itself. This causes large amounts of environmental pollution, especially since the denim industry uses about 40,000 tonnes of indigo every year, according to a 2015 report by the University of California. Denim mills have reportedly turned surrounding bodies of water blue, and indigo pollution has destroyed aquatic life and affected the health of workers and residents. In 2017, several dogs in Mumbai started to appear light blue after consuming toxic waste from the indigo dyeing process in a river. Similarly, the Pearl River in China has suffered from the large amounts of toxic indigo waste emitted by fast fashion factories. 

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Indigo is one of the oldest dyes in the world and a 2016 study published in Science Advances revealed that discovery of the first fabric dyed with indigo dates back 6000 years. Fabrics dyed with indigo made their first appearances in ancient India, ancient Egypt, Japan and West African cultures. The popular Indigofera tinctoria was first discovered by Peruvians and indigo was eventually popularized between the 15th and 17th centuries. Synthetic indigo was introduced in 1883 by German chemist Adolf von Baeyer and the invention paved the way for the first industrial mass production of synthetic indigo in 1897. Seven years after that, large quantities of synthetic indigo began to flood the market, and today, about 20,000 tonnes of indigo are produced every year.

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However, fewer than 1% of indigo dyes are derived from Indigofera tinctoria. Despite the existence of natural indigo, which is also aniline-free, producers of denim have been synthesizing indigo because the process of obtaining natural indigo from plants is tiresome, difficult and messy. The production of woad, for instance, the European version of indigo, was so smelly that Elizabeth I banned it from within an eight-mile radius of her palaces. In addition, indigo dyes derived from the Indigofera tinctoria plant do not provide the same level of colour consistency for companies needing to pump out replicas of a single product.

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“Using synthetic indigo for dyeing fabrics is a quick production process that requires very minimal time compared to the production process of natural indigo,” Baker notes. “The latter involves more physical labour which can go on for multiple days.” 

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However, in the age of conscious consumerism, shoppers are increasingly opting for natural fibres and dyes. In addition, some fashion houses are going back to plant-based indigo dyes in an effort to mitigate against the toxicity that comes with the denim industry. Stony Creek Colors for instance, will be providing their plant-based dye, IndiGold, to Levi Strauss & Company, which is known worldwide for its brand of denim jeans. The invention replaces petroleum-derived synthetic indigo and uses hydrogen as the reduction agent, thereby eliminating harmful byproducts from the dyeing and pre-reduction process. More brands have also vowed to launch jeans dyed with Stony Creek’s indigo, while mills in Europe and Asia have committed to using the distinctive dye. 

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Baker adds that the blue hue that comes with using natural indigo is impossible to achieve with synthetic indigo. “Denims dyed with natural indigo are more aesthetically pleasing,” she says. 

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Makers and artisans in the fashion industry have also echoed similar sentiments. Celia Geraedts, the founder of Blue Prints Amsterdam, told Denim Dudes in an interview last year that, when it comes to achieving the desired shade of indigo, there was absolutely no debate about choosing to work with natural indigo. 

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“The depth of vibrating blue hues can’t be replicated with synthetic dyes,” Geraedts said. “Being able to touch the material during the dyeing process allows me to act fast to correct folds and achieve even and quality results, something that brands which solely focus on producing with synthetic indigo aren’t able to do.” 

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However, working with natural agricultural products still comes with its limitations, like the uncontrollable variations that come with the weather, crop rotation and harvesting the product. For many, the largest obstacle is achieving consistent dye results without incorporating the use of chemicals. 

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Some organizations have argued that building various innovations into the dye production process could minimize the batch-to-batch variation that’s typical with natural dyes. For instance, Stony Creek Colors has adopted the use of uniform seed varieties, mechanical harvesting in the extraction process of natural indigo and batch-blending to standard formulation sizes based on a target indigotin value. Batch-blending, as explained by the founder of Stony Creek Colors Sarah Bellos, involves blending each batch of orders received to an exact purity of indigotin — the active dye chemical in indigo — which allows for consistent dyeing and minimizes any naturally occurring variation between lots. 

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Scalability is also an issue with natural indigo but a company like Fibershed — a non-profit organization that develops regenerative fibres — is currently conducting extensive research and testing to make the case for scaling natural indigo based on the water extraction and compost systems for production.

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Even though full adoption of natural indigo for denim dyeing is still a work in progress — which requires more solutions to the issues of scalability and high cost — Baker says she feels that the denim industry shouldn't put all their focus on matching the speed and volume of synthetic indigo. 

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“We should concentrate on understanding the specialty of the plant-based indigo process,” says Baker. 

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Perhaps denims dyed with natural indigo might be a bit pricier and more elusive, but the beauty of natural indigo lies in preserving and increasing its availability in the market.

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