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Axing Aniline in Denim Dyes? Not So Fast

Aniline is a problem for the denim industry. Or it isn’t. It depends on whom you ask.

Certainly the chemical, a building block for synthetic indigo, is the cause of some concern for Archroma, a Swiss specialty chemicals firm that debuted a so-called “aniline-free” indigo dye, which boasts undetectable levels of the agent, in May.

But is it so bad? The U.S. Environmental Protection Agency classifies aniline as a Group B2 human carcinogen, which means that while there’s some evidence it might cause cancer in people, the existing data is far from conclusive.

Aniline can pose other risks, however. It can cause skin allergies with repeated contact. And both short-term and chronic exposure to the chemical, either through the lungs or the skin, can impair the ability of red blood cells to ferry oxygen to tissues, which can trigger symptoms of hypoxia such as headaches, dizziness, increased heart rate, breathlessness and even unconsciousness, the EPA says.

It’s also “very toxic” to aquatic life, per the U.S. Centers for Disease Control and Prevention, which is where the biggest argument against it seems to lie. Out of the 400 metric tons of aniline waste that the indigo industry produces every year, roughly two-thirds winds up in wastewater discharge and eventually lakes, rivers and other waterways, according to James Carnahan, Archroma’s global sustainability manager for textile specialties.

The other third clings onto the indigo pigment—and therefore the denim itself—as an insoluble contaminant, one that cannot be rinsed off like most impurities. The only way to reduce the concentration of aniline on a pair of jeans is to reduce the amount of indigo.

“We tend to find that the concentration of aniline is directly related to the concentration of indigo,” Carnahan said. “If you removed half of the indigo, then you’ve removed half of the aniline. But you’re not getting any preferential removal.”

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While aniline “isn’t necessarily too bad for human health,” as Carnahan conceded, the chemical’s environmental impact was enough for Archroma to want to pivot away from it. And since the company stumbled upon a way to strip aniline from the denim supply chain, it thought, “Why not?”

“As a responsible manufacturer of textile dyes and chemicals, we always look at the unintended contaminants which are coming through as a result of either the raw material or manufacturing process,” he said. “We saw the opportunity to be able to have a product that contains less of a hazardous contaminant.”

Setting limits

It may be for this reason that aniline is increasingly appearing on a number of restricted substances lists, including those belonging to Bluesign and Oeko-Tex, which have set certain safety limits for the substance in its various forms.

You’ll be hard-pressed, on the other hand, to find an active movement to do away with the chemical entirely. Banning aniline, one source told Rivet, would also mean banning synthetic indigo, making the issue a non-starter. Another person familiar with the matter, who also chose to remain anonymous, suggested that aniline wasn’t as worth pursuing as other textile-processing chemicals with far more hazardous profiles.

Oeko-Tex’s Helmut Müller doesn’t consider the presence of aniline in indigo a priority problem, either.

“In our experience, aniline has only a small impact when testing denim products according to our Standard 100 by Oeko-Tex criteria catalogue, and it is only rarely detected. Higher concentrations can be detected even more rarely,” he said. “In our opinion, and according to our testing knowledge, the public discussion about aniline in denim fabrics and articles is overexcited.”

Make no mistake, aniline is a harmful chemical at high concentrations, but “there is no compelling evidence that there is a problem at the levels reported, even considering worst-case scenarios,” said Scott Echols, director of the Roadmap to Zero Programme at ZDHC, a consortium of brands, NGOs and value-chain affiliates, including Adidas, C&A, Gap, H&M, Inditex, Levi Strauss, Nike and Puma, that works to improve the apparel industry’s environmental standards.

“A misconception is to assume that because something is there at a certain concentration that it’s a problem or that high concentrations in the indigo dye mean that aniline will be present at the same high concentrations in the final denim,” Echols said. “Any chemical is harmful above a certain concentration and nearly all chemicals—aniline included—show no observable adverse effects below a certain level.”

In the event that aniline becomes verboten, the denim industry might find itself roiled by increased testing costs and a shift to purer—read: more expensive—dyes, Echols said.

“Any restrictions need to be made taking into account scientific data on the levels harmful in product so realistic limits are set to protect consumers, workers and the environment,” he added. “Without this, it could make the world’s most popular fabric a lot more expensive without any real benefit.”

Carnahan from Archroma is familiar with these criticisms. “There are other hazardous chemistries where a lot more effort is being put behind to restrict them,” he admitted. “So it’s probably low [urgency] there.”

His company, however, prefers to follow the precautionary principle: better safe than sorry.

“It’s better to basically avoid a problem that may occur in the future than actually take action at the time when somebody decides that it is a problem,” Carnahan said. “What we’re not saying is this is a problem everybody needs to deal with straightaway; what we’re saying is it’s an opportunity for us to remove, out of the value chain, a hazardous chemistry which up until now has been accepted.”

Plus, he added, why shouldn’t environmental impact carry as much weight as human harm?

With the Denisol Pure Indigo 30, Archroma is the first company to produce indigo, “from a synthesis perspective,” with such low levels of aniline. Other companies, Carnahan said, have tried to neutralize aniline from the indigo after the fact, which is an approach that’s both extremely costly and difficult to sustain.

Sustainable alternatives

Another way to create indigo without aniline is by going old school, namely by harvesting the pigment from the Indigofera plant. The reason brands don’t do this on a significant scale is because distilling natural dyes takes more time and labor than swilling chemicals. It also requires several tons of plant matter to produce a few pounds of dyestuff. Again, hardly cost-effective.

Carnahan estimates that roughly 70,000 tons of indigo goes to market every year.

“The amount of land area that you’d need [for natural indigo] would be significant,” he said. “And possibly there would be discussions about land for food versus land for other things.”

To completely eliminate aniline from denim, however, you’ll have to bypass indigo altogether. This, Archroma does, with Advanced Denim, a dyeing platform that can simulate the appearance of indigo using blue sulfur dyes. As a bonus, the technology uses 92 percent less water and 30 percent less energy than conventional denim-dyeing methods.

Though Archroma offers Advanced Denim as an alternative to indigo-dyed denim, “due diligence must be taken of the fact that maybe it doesn’t wash down the same; maybe the nuances of shade are not exactly the same as indigo,” Carnahan said.

The company, he added, continues to tinker with the process to “get a closer simulation to how indigo actually behaves on post-processing,” such as how it reacts to washing.

Whether Archroma makes a complete switch to aniline-free indigo dyes remains to be seen. It’s still early days for the new Denisol Pure Indigo 30, and word about the innovation is still filtering through the industry.

“It’s really up to the market to decide that this is the direction that they would like to go,” Carnahan said. “But I would say that the market will dictate the pace with which we will be able to replace a product which contains a higher amount of aniline with [one that has] lower amounts of aniline.”

That’s not to say there hasn’t been any interest. Several large brands have requested proving trials to see how the new dye performs. This will take time.

“They’d like to understand that the product is indigo and therefore behaves exactly as indigo does behave. They would also like to understand what the commercial impacts would be, perhaps,” Carnahan said. “ And we have to allow the brands that time to look at it and then come back to us with regard to a decision.”

This article is from the latest issue of Rivet. Download the entire issue here.