The desire for simple answers sometimes gets in the way of proper analysis, leading the industry and consumers astray. Case in point: leather.  

The emergence of plant ‘leathers’ in recent years has been a win for vegan consumers but a loss for the environment. Whilst the media is awash with stories about how plant leathers are ‘better’ than animal leathers, there are many factors to be considered before arriving at such a binary conclusion. Here we examine those factors by comparing leather from cattle hides to alternative ‘leathers’ that comprise plant, fungus (mycelium) and petrochemical inputs.

Animal leather has existed since primitive times when hides were used for warmth and utility, representing practical and optimal use of every part of the animal by carnivorous humans. But in the current industrial context, hides are a byproduct of a vast meat industry that causes high environmental and social impacts relative to the nourishment and sustenance it provides. Globally, grazing livestock occupies two-thirds of agricultural land, with one-third for crops¹ despite livestock providing less of the world’s supply of calories and protein². Note, however, that not all land is suitable for cropping.

The beef industry’s outsized environmental impacts are fuelled by consumer demand. For example, in the US, beef and cattle is the largest food industry by revenue at $70BN annually³ – no wonder biotechnology companies⁴ are developing lab-grown beef to satisfy consumer tastes, minus the environmental impacts. But whilst the traditional beef industry exists, so do hides – and there were around 32 million in the US alone in 2017⁵.  

Hides represent 1-3% of the value of the animal⁶, with only a small portion of beef industry impacts attributed to them compared to the meat.  

So some of the outcries over the impacts of cow leather are really an outcry over the impacts of beef, of which leather is a processed byproduct.

During leather production, hides undergo tanning (to stop them from biodegrading) and dyeing and finishing to meet end-user requirements. These processes can be chemical compliant⁷ or toxic (as with other textile dyeing and finishing processes). This raises the question: At what point is it ‘better’ for the environment and humanity to dispose of those hides instead of turning them into leather?

Is there a scenario where making leather from hides is less damaging than disposing of them for as long as the beef industry exists? Would it be irresponsible to stop making leather (in a non-toxic manner) from hides, given the damage they do when landfilled or incinerated?

I asked Dr Luis Zungo, Global Innovation Manager at Buckman⁸, Secretary of IULTCS⁹ and Board member of Leather Naturally¹⁰ if scenarios could be modelled (or exist) that render animal leather sustainable. He explained why hides are used to make leather, firstly from a resource-use standpoint:

Nature uses energy, water and chemicals to grow the protective skin that thermally regulates animals. “The skin contains fat, protein, water and collagen: one of the strongest materials on the planet. “When we make leather, we recover the proteins to make a product that can replace synthetics, be reused and repaired, and that biodegrades at end-of-life,” he says.

If not used for leather, hide disposal requires incineration or hydrolysation (to make fertiliser). Both of these processes use significant energy and generate waste. Hides left to biodegrade naturally attract toxic microbes during decomposition. Only a tiny portion of animal hides (mostly pig skins) are used for gelatin and collagen production. A key driver for sustainable leather production is optimising the chemistry used, particularly in dyeing, explained Dr Zugno. But this is a problem shared by the entire textile industry, where dyestuffs account for a large proportion of total environmental impacts.

Is vegetable tanning the answer to leather’s chemical impacts? No, and for reasons that will be expanded in a follow-up Intel piece here on Techstyler next week.

Where chrome tanning is concerned, Dr Zugno explains that use is restricted and closely monitored according to restricted substance lists, particularly for the toxic Chrome 6. Hides are shipped internationally, pre and post-processing, and strict chemical compliance across borders is essential for import and export. According to Dr Zugno, most of the world’s tanning occurs in Italy (around 20%), followed by China, South Korea and Vietnam (which seems to logically follow the footwear manufacturing hubs).

Despite his explanation of leather being “a fully viable material”, regarding animal welfare, Dr Zugno admits: 

“For ethical reasons, I do not eat meat.” 

Furthermore, he asks: “Why is branding still legal? This is animal cruelty – it is not necessary, it [continues] because it is economical”.

Having spent 47 years working in the tanning industry as a chemist and educator, he believes there is much room for improvement in the leather industry. The focus, he says, should be on new solutions that reduce the impacts of leather production rather than replacing leather with plastic alternatives. So why has plastic ‘leather’ increased in popularity, and how did it come to compete with leather?

The vegan movement has been a driver for the expansion of non-animal ‘leather’ consumer goods¹¹. Veganism has cultural, ethical, environmental and nutritional drivers and has had a rising influence on consumer culture. Non-animal ‘leather’ has been heavily marketed as ‘vegan’ at a time when the environmental impacts of methane emissions and forest clearing from cattle farming are of global concern. 

This creates a blind spot, where ‘vegan’ has become shorthand for ‘good’ and animal leather ‘bad’.

Another critical consideration is that vegan ‘leather’ is a marketing term that, in truth, can mean ‘made from anything but animals. Vegan’ leather’ is attributed to materials containing only petrochemicals, a combination of plants or mycelium and petrochemicals, or from plants or mycelium only (of which there are very few, and even fewer that are commercially viable today). 

‘Plant’ and ‘plant-based’ ‘leather’ are also marketing terms that do not describe the complete ingredients of the material. Many of these ‘leathers’ contain petrochemical-derived polymers to help achieve the performance characteristics of leather¹². They can also undergo a tanning-like process which may or may not use toxic or restricted chemicals.

Here we arrive at a kind of ‘leather’ crossroads between cattle leather, plastic leather, plant/plastic ‘leather’, fungus (mycelium) and newly emerging plant-only ‘leathers’. On the one hand, creators of plant/plastic leather use plant matter or waste from agricultural processes that require less land than cattle farming (other environmental impacts notwithstanding). But on the other hand, their petrochemical-derived components are known to have under-reported implications¹³ and cause pollution during degradation. This underreporting is the subject of ongoing debate, stoked by the exclusion of plastic pollution during use and disposal from the typical life cycle assessment scope, which is cradle to gate (raw material to dispatch to end customer). Vegan, in this case, can mean toxic, which is not communicated clearly and contributes to the binary narrative that vegan (including plant/plastic leather) is ‘better’ than animal leather.

A further area for disambiguation is plant leather versus mycelium ‘leather’ because the technology, material properties and processing vary greatly. However, that requires an independent assessment in a separate article.

For now, the decision to use animal leather or alternative ‘leather’ requires consideration of the ethical, raw material, processing, use and end-of-life consequences, rather than binary deductions based on whether the raw materials are derived from animals or plants. It should most certainly assess whether they contain synthetic polymers.

To dig further into this topic and plant ‘leather’ applications, see our recent NFW x Allbirds feature and stay tuned for the Innovation Spotlight on Mirum, landing in the Intel Database later this week.

Further resources

^{1 Materials Innovation Initiative White Space Report
2 Next-Gen Materials consumer research
3A guide to how cow leather is made in the 21st century
4 Consumer sentiments about leather and its alternatives}