The debate over whether animal leather is a sustainable material or not has led many consumers to fixate on purchasing vegan alternatives. In 2020 the digital-first retailer Lyst had a 178% spike in page views for “vegan leather.” As brands race to appear more sustainable, many have made the material the entire backbone of their sustainability messaging.
The manufacturing process of animal leather is extremely toxic, involving the heavy metal chromium III and IV and other hazardous substances. But disguising the damaging nature of synthetic manufacturing under the label of vegan is disingenuous — all “vegan leather” currently available for purchase incorporates some fossil-based synthetic materials. We would even call it greenwashing.
How is Synthetic Leather Made?
The “vegan leather” you will find filling up racks at Zara or Aritzia is either polyurethane (PU leather) or occasionally polyvinyl chloride (PVC leather).
PU leather is made by coating one side of the fabric (usually polyester) with polyurethane. There are two manufacturing processes for PU leather, the most common process is the “wet process”, which is characterized by submerging the fabric in liquified polyurethane, water, and solvents, baking it, then detailing the material to mimic leather. The “dry process” eliminates the liquid and directly laminates the polyurethane to the fabric; this process requires less water and energy.
Making PVC leather is a similar coating process. Polyvinyl Chloride is mixed with stabilizers, plasticizers, and lubricants and then sent through various heating processes, creating chemical changes to set the paste onto the fabric.
Synthetic leather gives fast fashion retailers a cheaper and nearly realistic alternative to animal leather, which encourages the overproduction of accessories compared to higher-priced, artisan leather products. Just as importantly, the process is extremely chemical-intensive and puts the health of those that work throughout the manufacturing process at great risk. The wet process for PU leather requires the restricted solvent dimethylformamide (DMFa). It can be absorbed through the skin, causing potential damage to the liver, irritation to eyes and skin, dermatitis, and digestive problems. PVC manufacturing utilizes toxic vinyl chloride and the restricted plasticizers phthalates, adverse health effects include impaired pulmonary function and infertility in men. Phthalates are metabolized in a few days, meaning it is especially difficult to quantify its impact.
Synthetic materials by nature cause damage throughout their lifespan. Greenpeace has labeled PVC as the “poison plastic”. Polyvinyl Chloride actively emits chlorine-based compounds into the air, waterways, and food chains even after you buy it. PVC is not biodegradable and also leeches dioxins into the atmosphere when incinerated, like many unsold and trashed fashion products are. The United States’ current exposures to dioxins are from decade-old releases, but dioxin contamination is an increasing burden in developing countries, particularly because of the unmonitored burning of trash.
Not only is the manufacturing process of these synthetic materials chemically intensive, but being fossil-fuel derived it is also carbon-intensive. Artificial leather is said to emit 15.8kg of CO2e emissions per square meter, and polyester 20.6kg CO2e. While it’s hotly debated whether the emissions from raising cows can be counted toward natural leather’s impact, if you measure its carbon footprint from the slaughterhouse onward, only 17kg of CO2e is emitted per square meter of leather. Since artificial leather and polyester are not a by-product of another industry, their carbon footprint can be viewed as more impactful than natural leather.
Can Vegan Leather Be More Sustainable?
There are more sustainable manufacturing processes of PU leather being used in the fashion industry. Stella McCartney’s “Alter Nappa” is still made from polyurethane, polyester, and recycled polyester. However, the polyurethane is water-based and solvent-free. On the more affordable side, H&M began restricting DMFa in 2007 in its supply chain and by September 2020 had achieved 79% DMFa-free PU materials.
What about Plant-based Vegan Leathers?
Some companies claim to incorporate plant-based materials into leather alternatives. But when asked to share what exactly is in these “vegan” products, many vegan brands are loath to say.
For example, the Mexican cactus leather startup, Desserto, has so far declined to answer any of EcoCult’s questions about why it’s only “partially biodegradable,” and reportedly makes brand partners sign a non-disclosure agreement so they cannot share either. (We were told by a source that it has polyurethane in it and confirmed this against a materials list in a company profile on the Materials Innovation Initiative, an accelerator that supports Desserto.) Apple leather also has polyurethane. The Mylo Adidas tennis shoe prototype used petrochemical synthetic binders, and Piñatex, and a PU finish.
The one exception, starting this week, is MIRUM, an a plant leather developed by the startup Natural Fiber Welding. It’s 100% USDA biobased certified. The material is made from a combination of virgin and recycled plant fibers and doesn’t include polyurethane, polyvinyl chloride, ethylene-vinyl acetate, or petrochemicals. MIRUM is also a circular material. Natural Fiber Welding claims that once a product made of the material comes to the end of its life, it can be disassembled, ground up, and recycled for future material production. It’s been picked up by major retailers Ralph Lauren, who included MIRUM in Team USA’s official Olympic uniforms, and Richemont and had investment by Allbirds and BMW i Ventures.
The debate between animal and synthetic leather is not likely to end anytime soon. Determining which is the more sustainable choice comes down to what you as a consumer prioritize: a plastic-free environment or eliminating animal agriculture. Hard choice, isn’t it?
If you do opt to go down the synthetic route, avoid PVC at all costs and shop from brands that value transparency and give insight into their manufacturing and chemical management policies.
And of course, as we always say, buying secondhand or nothing at all is even better.