The Difference Between Toxic and Non-Toxic Dyes

The topic of dye toxicity is an incredibly confusing one, even to experts. 

For years, if I’m honest, I’ve sort of slid past that whole subject, afraid to really dive in lest I drown in the science of dyes, pigments, and colors. I opted to repeat the vague assurances by brands that the dyes they use are “non-toxic,” “low impact,” or “natural,” without truly understanding what that means. 

I heard about how azo dyes had been banned, then was handed a colorsheet of azo dyes samples to peruse at an artisan weaving unit in India. Wait, what? I could not figure out what the deal was. 

Now, after spending two years writing a book on the subject of toxic fashion, I finally feel ready to tackle this topic. 

So, are synthetic, conventional dyes bad for you? Will they give you cancer, or cause you to break out in a rash or hives? And if so, how do you — as a regular shopper or a fashion entrepreneur — make sure your clothing is healthy and safe? 

When it comes to dyes and their effects on our health, it’s not so (forgive me) black and white. Dye toxicity exists on a continuum. Some only cause a reaction in more sensitive people, while some are known to be toxic and even carcinogenic. 

But there are some general concepts that will help you wrap your head around dye toxicity. Let’s get into it. 

Natural Dyes Versus Petrochemical Dyes: Which Are Safer? 

Let’s start with this basic fact: almost all dyes used in fashion and home textiles today, unless otherwise explicitly stated, are created from petrochemicals. 

There are thousands and thousands of dye chemicals that have been created and used since the invention of fossil-fuel dyes in the 1850s, and many of their ingredients, like toluene and benzene, have turned out to be pretty toxic. 

However, the synthetic dyes themselves are not generally considered to be toxic to wearers…at least, as far as we know. We haven’t been able to test all these thousands of dye substances to be 100% sure they are completely benign against our skin. But so far the evidence is not showing that it’s not a rule that you should be fearful of all synthetic dyes. 

The thing is, though, as a consumer there are very few ways for you to tell which type of dye was used on a fashion or home textile product, and how. Sloppily and cheaply? Safely and thoughtfully? The end result looks almost identical.

Natural dyes made from plants, minerals, and insects are generally regarded as being safer than synthetic petrochemical dyes. There are some natural dyes, such as logwood, that can contain toxic substances. But the biggest problem is that a mordant of heavy metal salts may be used to fix the natural dye to the fabric. This is not the norm, however, and there are safe mordants, or alternative ways to fix the dye. One example is an innovative ultrasonic process to press the plant molecules into the fiber, guaranteeing color fastness.

If natural dyes are generally regarded as safer, why don’t we use them as a rule? Well, they’re more expensive, more difficult to use at a large scale, and — as they are most often sourced from small farms that are subject to the seasonal variations of nature — aren’t as easy and quick to source as petrochemical dyes. 

Cheaper and easier? Yep, you know what the fashion industry will use. 

How Heavy Metals Get into Clothing Dyes

Heavy metals, which include antimony, arsenic, barium, cadmium, chromium, lead, mercury, and nickel, are the original sin of the toxic fashion industry. 

For hundreds of years, mercury was used to felt rabbit fur for men’s hats, and lead was used in white makeup. The most popular color in Victorian England was arsenic green. High society women wore fantastically toxic ballgowns and floral headdresses that threw off poisoned dust as they danced the night away. 

While things have gotten better (we don’t cover our dresses with what is effectively rat poison anymore) according to the industry group Afirm, heavy metals can still show up in the coloring of finished products. They’re used to cheaply create certain colors, or added to brighten them. Chromium, cobalt, nickel and copper may be found in certain dyes. Antimony, arsenic, barium, cadmium, chromium, lead, mercury, and nickel may be found in some pigments. 

Heavy metals are linked to several types of toxicity: Arsenic, cadmium, cobalt, and nickel are linked to cancer. Barium, lead, and mercury are linked to kidney, brain and reproductive toxicity. And arsenic, cadmium, and mercury are acutely toxic at high enough amounts. Heavy metals also can build up in our tissue, causing devastating mental and physical symptoms that are hard to pin down and diagnose. 

There is legislation in Europe and California restricting the presence and use of heavy metals like cadmium, chromium, arsenic, and lead in consumer textiles. In the U.S. at the federal level, cadmium and lead are restricted in children’s products. But there’s not much checking being done of clothing and accessories — adults’ or children’s — for heavy metal contamination. When clothing is checked, heavy metals are often among the toxic components. 

For example, when a Southwest Airlines attendant had her uniform tested in 2020 because it was making her ill enough to lose her hair, a private lab found elevated levels of fourteen heavy metals, including chromium, arsenic, mercury, and lead. A test of an Alaska Airlines uniform by a Washington State lab in 2012 found antimony, lead and arsenic. And when American Airlines had its uniforms tested in 2016 because attendants and pilots were getting sick, the lab found antimony, arsenic, and cobalt. 

The American Apparel & Footwear Association came out with a report in 2022 showing that out of forty-​seven counterfeit products it had tested, seventeen failed for things like arsenic, lead, and phthalates. One product had six thousand times the limit of cadmium.

In 2019, the advocacy organization Green America launched a campaign against children’s brand Carter’s, pointing out that in recent years, Carter’s had reported to the Interstate Chemicals Clearinghouse’s High Priority Chemicals Data System that it had used arsenic and cadmium in its products. (Carter’s eventually instituted a Restricted Substance List.)

Not all of these instances of heavy metal contamination were from dyes — it could also be from metal coatings and alloys, PVC manufacture, or leather tanning. But dyes are one of the biggest ways heavy metals find their way into our fashion. 

Are Azo Dyes All Toxic?

If you’ve read anything about fashion and sustainability, you’ve probably developed a vague sense that azo dyes are bad. But they’re also very, very popular. A large class of synthetic dyes made from fossil fuel sources, they make up 70 percent of the 9.9 million tons of industrial dye colorants used globally each year. 

Twenty-two azo dyes are banned in the European Union because they have been shown to release amines when in contact with our skin bacteria, and many amines are suspected to be carcinogenic, mutagenic, and genotoxic, meaning they could cause genetic changes in human cells, along with cancer. No azo dyes are banned in the United States. 

The fashion and chemical industries have tried to assuage our fears of azo days in a few ways. First of all, some companies argue, it’s only about 5 percent of all azo dyes that release these toxic amines. But most azo dyes have not been studied enough — or even categorized and named — in order to make this claim so confidently. 

Second, the industry maintains, too little of these amines would get into our bodies from fabric to cause us any harm. It’s not like you’re eating your clothing, an industry expert told me while I was researching my book on the topic of toxic fashion, To Dye For. 

That’s not quite true. Setting aside skin contact with dyes, recent research out of Duke shows that azo dyes shed off clothing and home textiles into our house dust, which means we can ingest and breathe in these substances. The Duke researchers also found azo dyes comprised over 1% by weight of a children’s sport t-shirt. That’s a lot of dye. 

Though fashion brands and their manufacturers have stated that they’ve voluntarily phased out the azo dyes commonly accepted as hazardous (“restricted” azo dyes) these azo dyes tend to keep showing up, especially in cheap clothing. A 2020 study found their amines in half of the 150 textile samples researchers tested, and other research showed that in a quarter of the samples tested, they are present at high enough concentrations to be concerning for our health.

Polyester Dyes

There’s a special type of azo dye used on synthetic clothing called azo disperse dyes—as in, they are dispersed in a water-​based solution for dyeing synthetics like polyester. If you think about the difficulty of dying a plastic bag, you understand why you would need a special type of dye for synthetics. 

Disperse dye might be the reason you or a loved one claims that polyester makes them itchy or break out. It’s not necessarily the polyester itself, but the type of dye used on it. 

Dermatologists know that certain disperse dyes, like Blue 106 and 124, are common skin sensitizers, meaning they can cause rashes and hives. If you go into your dermatologist with serious skin issues, they might give you a patch test to see what is causing it, and disperse blue and black are commonly included in the set of about 80 potential sensitizers. One European study of people who got patch tests found that almost 7% of people tested had a disperse dye allergy. 

But there might be more to it. When researchers at Duke purified and catalogued 12 azo disperse dyes, they proved that all 12 could initiate a skin allergy. So azo disperse dyes in general, not just the ones commonly used in tests by your dermatologist, or the ones that have been phased out (supposedly) by the fashion industry, have the potential to cause reactions. And the more azo disperse dye in a fabric, the higher the potential for a reaction. 

The French Agency for Food, Environmental and Occupational Health & Safety (ANSES) ran a biomedical study in 2018 that connected skin reactions in fifty patients to specific chemicals found in their clothing. In 2022, based on these results, it called for disperse dyes to be banned.

Quinoline Dyes

The European Union also restricts quinoline dyes in consumer textiles because quinoline is known to be carcinogenic. According to Afirm, it shows up as a contaminant in some dispersing agents for dyes. A 2014 Swedish study found quinoline in many samples of clothing — it was especially prevalent in polyester clothing, though it showed up in high amounts in an organic cotton baby bodysuit. 

How Do You Avoid Toxic Dyes? 

Like for many hazardous chemicals used in fashion and home textiles, the best way to avoid toxic dyes is to buy from reputable brands with strong chemical management programs. You could shop at mass-market brands like Levi’s, Nike, and United Colors of Benneton if you’re on a budget, or shop secondhand.

If you have a skin condition or allergies, consider shopping at a brand that specializes in non-toxic clothing and brands that use natural dyes. Try to stick to natural fibers like cotton, linen, silk, hemp, lyocell/Tencel, modal, and bamboo rayon. Some brands even offer undyed textiles, like alpaca in natural colors, unbleached and undyed cotton, and heritage cotton that grows in pastel colors. Also only buy natural-fiber bedding, since you spend up to eight hours or more a night wrapped in your sheets. 

You should also try to avoid synthetics like polyester, especially if it’s something that will go against your skin, like underwear, socks, leggings and t-shirts.

Finally, look for brands with labels denoting safe chemistry, such as bluesign and Oeko-Tex.