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, the company’s global sustainability manager for textile specialities.
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.