Dyes and their environmental impact: can we find a solution?

This past decade, we have seen an exponential increase in the volume of textiles processed, reaching a breath-taking 111 million tons of fabric manufactured in 2019, doubling production over the past 20 years. Accompanying this movement is a visible increase in pressure upon the supply chain to produce fibre faster, to fashion this volume of clothes. The textile industry has responded to demand by shifting production to places where workers are paid little, and manufacturing remains unregulated.  Textile Exchange and UNEP both state “awareness of sustainability and circularity issues in the textile industry has never been higher”, yet pollution levels due to textiles have continued to increase. 

Although we have no aggregated figures for effluent pollution, our industry is notorious for its release of chemicals into the waterways. Wet processing is the phase showing the highest impact on the environment, not only because of the vast amounts of water needed to dye, wash, steam and finish fabric; but the fact that dye effluent from synthetic dyes pollutes the local waterways rendering them unfit for any other use. This problem is exacerbated by production remaining in the hands of SMEs situated in the developing world, they are poorly regulated and cannot afford Effluent treatment plants.

Thus, we see the example of the Citaram river in Indonesia, the most polluted river in the world, where a growing profusion of textile plants release effluent directly into the river. This has severe consequences on both aquatic life, agriculture and public health: the river irrigates the rice paddies and local food crops, people use the water to wash with and wash their vegetables in. Hair taken from children living near the Citaram revealed the presence of 52 persistent organic pollutants, all chemicals known to be mutagenic or carcinogenic. This has explained the huge incidence of liver cancer, kidney failure and skin conditions in the local population.

Although Europe sticks to strict REACH restrictions, India, Bangladesh and Indonesia do not, and wastewater is often released untreated. Estimations of the amount of chemicals we use vary hugely according to reports: from 10000 chemicals according to Intech open, to around 3500 chemicals according to[1]UNEP[2]. An Indian study estimates around 10000 different dyes and chemicals are used, amounting to 700 000 tons of synthetic dyes produced annually.[3]Indeed although our industry used and traded natural dyes for millennia, and our knowledge of producing dye from plants is vast and accumulated over centuries, since Perkins invention of Mauveine in 1856, synthetic dyes based on fossil fuels have dominated the market. Today, 99% fabric is dyed with synthetic petro-chemicals, natural dyes represent only 1% of the market[4].

Dyes are soluble and penetrate into the fibre by forming covalent bonds, changing the crystal structure of the molecules they adhere to. The dye, unlike a pigment, is thus embedded into the fabric. However, due to inefficiency of the dyeing process, 15 to 20% of dyestuff is washed away and lost to effluent. Due to their high solubility, it is difficult to remove them. An estimated 200 000 tons escape treatment processes and persist in the environment[5]. As many of them have added anti-microbial agents to them, they are resistant to biological degradation. 

Synthetic azo dyes in particular are known to be carcinogenic and also mutagenic, disrupting the endocrine system, posing a severe risk to human health, some being able to change the sex of fish. Other dyes are direct dyes, acid dyes, reactive dyes, basic dyes and vat dyes, many of these use soluble salts and heavy metals. Dye effluents are thus loaded with heavy metals such as chromium, lead, iron, copper and zinc. However, the first issue is turbidity and colour: this obstructs photosynthesis, depriving water of oxygen and modifying the ph, thus threatening aquatic life.

Despite regulations, out of 4000 dyes still available on the market that were tested for toxicity, more than 100 still contained carcinogenic amines[6]. So why do we continue to dye with toxic synthetic products derived from fossil fuels when so many regulations and awareness campaigns such as Greenpeace’s ZDHC detox initiative have informed us of the risks? Is it just a lack of education, habit or pure economy? The value of colour and the dye process has decreased so much, that most buyers do not even factor it into their budget.

As we try to reboot production during this pandemic, we observe from all corners that the “post-corona-sapiens” is crucially aware of man-made degradation of the natural world. And, as we face the Sixth mass extinction, we realise we must make every effort possible to save and restore biodiversity and reduce our toxic impact on other living species. We cannot continue to dye as we do now, the sustainability imperative we face imposes change.

Botanical dyes offer an obvious solution to this dilemma. Using recipes from the past, and informed ethno-botany, many people are trying to rapidly construct a new botanical supply chain of dyes for the 21st century. Without the use of traditional metal mordants of the past, contemporary natural dyers are exploring ways to extract pigment from plants more efficiently and build up knowledge that has been left in the realm of artisans, to adapt scalable solutions for industry. Natural dyes have been used by craftsmen and women, indigenous artists, textile restorers and historians continuously, thanks to them, our knowledge of botanical colour has been preserved. However, today, we must explore new methods of dyeing, growing plants and extracting dyes that are reliable as well as regenerative for our environment. Studies have been made to ensure reforestation through agroforestry projects, others to test the biodegradation of botanical dyes in textile effluent[7]. It is proven that botanical dyes offer a sustainable solution as they are renewable, can be cultivated and harvested in a regenerative manner, and are safely biodegradable.

A whole community is studying everything from the preservation of tinctorial plants to bacterial dye systems, consistent extraction methods of producing pigment from food waste and the use of myco-remediation to break down dye effluent…

Indeed, there are botanical solutions for dyeing and producing colour, but also bioreactors and plants such as nasturtium officinale, that can be used in phytoremediation, where plants can use their hairy root systems to absorb toxicity and alleviate environmental stress. Working with Nature instead of against her, we could safely restore beauty to the art of making colour.

[1] Intech open: textile dyes: Dyeing Process and environmental impact

[2] UNEP: sustainability and circularity in the textile value chain 2020

[3] Textile dyeing effluents and environment concerns; M Islam and M Mostafa 2018

[4] Natural dyes: Sources, Chemistry, Application and Sustainability issues; S Sujana and A. Raja, Central institute for research on cotton technology, Mumbai

[5] Intech open: Textile dyes: Dyeing process and environmental impact

[6] Effects of textile dyes on health and the environment and bioremediation potential of living organisms, SBBiotec, Lellis & Polonio& Pamphile  

[7] Cultivation and extraction of natural dyes for industrial use in natural dye textiles production, European Commission, L Thuringen.