Colour at a Cost: How Fabric Dyes are Affecting People and the Planet
We talk a lot about what clothes are made from, who made them, and what happens when we’re done with them. But before a garment ever reaches the retail rack, its colour has already left a footprint.
Dyeing is an often-overlooked stage of clothing production, but the colour trends that change with the seasons carry a hidden cost that rarely appears on a price tag.
Toxic wastewater, polluted rivers, and harm to people, animals, and ecosystems downstream from textile factories can all be consequences of conventional dyeing practices. Understanding where the colour of our clothes comes from, and what it leaves behind, may change the way you think about getting dressed in the morning.
The Chemistry Behind the Colour
Most clothing produced today gets its colour from petrochemical-based synthetic dyes. These dyes emerged in the mid-nineteenth century and now dominate global textile production. In 1856 when William Henry Perkin accidentally synthesised mauveine from coal tar, the industry shifted rapidly toward chemically derived pigments that were cheaper, brighter, and more stable. Before this, colour came from natural sources like plants, insects, and minerals.
Today, synthetic dyes fall into several categories of dye application:
Reactive dyes form a strong chemical bond to cellulose fibres like cotton and are among the most widely used.
Disperse dyes are applied to polyester and other synthetics at high heat.
Acid dyes work on protein fibres like wool and silk by bonding the dye to the fabric in an acidic environment.
Vat dyes require a reduction and oxidation process to fix colour to fibre where fabric is immersed in large containers of dye.
Direct dyes are applied to the fabric directly with no chemical bonding process. Each category involves its own chemistry, its own fixation process, and produces its own chemical waste.
These categories describe how dyes are used, but dyes can also be grouped by their chemical structure. Azo dyes, for example, are the largest class of synthetic dyes and can appear across several dye application categories. Each dye type involves its own chemistry, fixation process, and potential waste streams.
Understanding how fabric dyeing works helps us better understand the problems it can cause.
The Environmental Cost of Synthetic Fabric Dyeing
Current dyeing practices give clothes the vibrant, lasting colours we’re drawn to, but at what cost?
Dyeing is one of the most water- and chemical-intensive stages of clothing production. In conventional processes, large volumes of water are used to apply colour to textiles, often alongside chemical additives that help dyes bind to fabric, brighten colours, or improve durability.
The problem is what happens next. When wastewater from dyeing is not properly treated, dyes and auxiliary chemicals can be released into surrounding waterways. From there, they can pollute rivers and soil, move through larger water systems, and affect ecosystems, livestock, and communities downstream.
In regions of Bangladesh, China, India, and Indonesia, where fabric dyeing is heavily concentrated, the effects are visible. Rivers run the colour of the season's most popular clothing shade.
These are only some of the effects of these harmful fabric dyes on the environment.
The Impact Travels Downstream
The consequences of dyeing do not stay within the factory.Every wash cycle releases small amounts of dye into domestic wastewater, particularly in the early washes of a new garment when unfixed dye is still present. This is a less significant source of pollution than industrial discharge, but it is not insignificant at scale.
Fixation of dyes to fabrics is a central part of the issue. Reactive dyes, used on the majority of the world's cotton clothing, have fixation rates of 50–80% meaning that up to half the dye is washed away.. A substantial portion of the dye passes straight through the fabric and into the wash water. That unfixed dye is resistant to conventional wastewater treatment, frequently entering the surrounding environment as a result.
There are also questions about what impact dyes have on the people wearing them. What is harmful to the environment is almost always harmful to humans.
Skin is our largest organ and is permeable. Clothing sits against skin for hours at a time. Disperse dyes, common in polyester sportswear and swimwear, are among the most frequent causes of textile contact dermatitis. The dye migrates to the skin surface with heat and friction, and can trigger chronic allergic reactions.
Azo dyes are the largest class of synthetic dyes. They are restricted in certain countries because some can break down into aromatic amines, a group of chemicals that includes known or suspected carcinogens. While these dyes are regulated in some markets, they may still be used in places with weaker chemical controls.
The concern is that, under certain conditions, azo dyes can break down in the environment or on the skin, potentially releasing harmful compounds into waterways, ecosystems, or direct human contact. Some studies have also raised concerns about possible links to cancer risks and endocrine disruption, though impacts vary depending on the specific dye, exposure level, and conditions.
Heavy metal mordant dyes, often used to fix colour to fibres such as wool, can also pose risks when not properly managed. For example, improper use of chromium-based mordants can contribute to the formation or release of hexavalent chromium, also known as chromium VI, which is toxic and carcinogenic.
To take a deep dive into the problems caused by fabric dyes, and their impact on human health from factory workers to the people wearing the finished clothes we recommend you check out To Dye For by Alden Wicker.
The Limits of Regulation
In the European Union, REACH regulationsrestrict or ban a number of harmful substances that can be used in textile production, including some associated with dyeing and finishing. Similar chemical restrictions exist in markets including Japan, South Korea, and, increasingly, parts of the United States.
But regulation is only as effective as its enforcement. In fashion, enforcement is complicated by the fact that most clothing is not made in the same countries where it is sold. A garment may be dyed in one country, assembled in another, and sold in a market with very different chemical rules.
In many cases, regulations focus on whether the finished product contains restricted substances by the time it reaches consumers. But that does not always address the pollution created during production, especially when dyeing wastewater is released near the factory. This creates a gap: the countries and communities bearing the environmental burden of dyeing are often not the same ones with the strongest market power, regulatory systems, or enforcement capacity.
Recent investigations show how difficult this can be to police. In 2025, Greenpeace Germany reported that 18 of 56 Shein garments and shoes tested (32%!) exceeded EU REACH limits for hazardous chemicals, including three children’s items. Some jackets exceeded PFAS limits by up to 3,300 times. The findings point to a broader enforcement challenge: when ultra-fast fashion products are sold through global online platforms and shipped directly to consumers, regulators may struggle to keep pace.
The Zero Discharge of Hazardous Chemicals, or ZDHC, programme represents an industry-led attempt to address chemical use further upstream. Its Manufacturing Restricted Substances List sets out chemicals that are banned from intentional use during textile, apparel, and footwear manufacturing. Adoption has grown across parts of the industry, but ZDHC remains a voluntary framework rather than a government regulation. That means its effectiveness depends on brand participation, supplier implementation, testing, and credible verification across complex supply chains.
Colour Is Not Neutral
The colour of a piece of clothing is not just a design choice. It is the result of a chemical process carried out at scale, with impacts that can travel through supply chains, waterways, ecosystems, and communities in ways that remain largely invisible to the buyer.
That does not mean colour is inherently bad, or that synthetic dyes have no place in a more sustainable fashion industry. Researchers and innovators are working to improve dye chemistry, reduce water use, develop colourants from biological rather than petrochemical sources, and build closed-loop systems that contain, recover, and reuse chemicals instead of releasing them into the environment.
But these shifts will not happen overnight, or without stronger oversight, regulation, and enforcement. But, when we all better understand what producing colour can cost, we are all better equipped to help push for the systems, standards, and accountability needed to make those costs harder to ignore.
