In recent years, the world's demand for leather products has increased. This makes the debate about the sustainability between real leather and synthetic leather and the assessment of which of these has the greatest impact on the environment significant.
Environmental sustainability today represents an increasingly important parameter for consumers who consider it like the others among the factors to be evaluated during the purchase phase.
Definition of leather
The correct definition of leather is "natural material, made up of collagen fibers deriving from the skin of an animal that undergoes a manufacturing process called tanning".
Therefore, it is not correct to indicate with the term "leather" all those products made with different materials and methods.
Products made from synthetic materials that possess similar characteristics to leather are referred to generically as leatherette (or synthetic leather) products.
Real leather is 100% leather skin. It is also called genuine leather. We refer to bovine, goat and sheep skins, i.e. of animals slaughtered for food purposes (not so the case of so-called "exotic" animals).
These hides are subjected to "tanning", i.e. the manufacturing process by which decomposition is blocked and a clean, robust and breathable material is obtained.
Full grain leather
Full grain leather is a very fine type of real leather free of blemishes that has not been sanded or buffed after hair removal.
It is a very high quality leather that is obtained by shaving the upper layer of the animal's epidermis before subjecting it to tanning.
The result is a thinner and more flexible leather suitable for example for making bags or other products that need a certain elasticity.
Nappa is a very smooth and highly prized real leather for its characteristics of softness, suppleness, breathability and durability. It has open pores and for this reason it cannot be treated with inorganic paints.
Bonded leather is a combination of real leather and synthetic leather. It is a material that has a lower percentage of animal skin obtained from processing waste (waste that would be thrown into landfills) combined with PU and other synthetic materials.
Ecological leather is not artificial leather, but real leather of animal origin.
The prefix eco- indicates that the tanning process is carried out with a low environmental impact and is called "vegetable tanning".
Vegetable tanning provides for greater efficiency from an energy point of view, the presence of water purification systems, the replacement of chemical substances for the treatment (chromium) with natural vegetable substances extracted from trees (tannins), a natural drying and not with machinery and a reduction in the volume of water used in processing.
Furthermore, with vegetable tanning there is a recycling of waste materials. They are used in the agricultural sector as components of fertilizers, in the building sector for the manufacture of building materials and in the cosmetic sector.
The term eco-leather is often associated with the concept of fake leather since in the early 90s it was used to indicate synthetic leather. Later it was decided to define genuine leather tanned with more environmentally friendly methods as eco-leather.
Leatherette (also called synthetic leather) is an artificial material (for example polyurethane (PU) or polyvinyl chloride (PVC)) which is made up of basic natural and/or synthetic fibers with a plastic coating.
It has the appearance of real leather, but differs from the latter in terms of properties (for example, it is not as breathable or resistant as genuine leather).
It is a product which, not being of animal origin, is cruelty free and for this reason it is also called "vegan leather".
Recently, new, more eco-friendly ways are being explored for the production of leatherette using, in particular, organic materials such as orange peels or wine production waste (the so-called "pomace").
What is more sustainable between real leather and synthetic leather
In the disquisition between who is more sustainable between real leather and artificial leather, it is necessary to evaluate not only the various environmental sustainability factors of their production processes (such as the consumption of resources and greenhouse gas emissions), but also a series of related parameters to the life cycle of the materials themselves.
The environmental sustainability of production processes
Use of chemicals
The processing of real leather represents one of the oldest industries in human history and, as previously mentioned, its production cycle starts from the skins of animals killed for food purposes which, otherwise, would become waste that is not so easily disposable.
The hides are then tanned using, in most cases, chemical substances, including toxic ones (including chromium) and using large volumes of water.
The chromium used for leather tanning is hexavalent chromium, which is toxic both for humans and for the environment. More than half of the chromium used becomes solid or liquid waste that contaminates soils and rivers.
Another phenomenon to consider following the tanning process is the eutrophication of water.
This term indicates an excess in the concentration of nutrients (nitrogen, sulphur, phosphorus) in rivers and seas with a consequent increase in biotic activity and a lowering of the oxygen level up to asphyxiating conditions.
Today the requirements for what concerns the use of chemical substances in the manufacturing processes of real leather are much more stringent than in the past thanks to high quality standards in the regulatory environment and corporate initiatives, on a voluntary basis, which tend to eliminate the hazardous chemicals as much as possible.
The production process of synthetic leather is not free from being a source of pollution as well.
First of all it must be said that we are talking about non-natural polymers which, in the case of PVC, also assume a connotation of toxicity linked to its possible content of dioxins, notoriously harmful to human and environmental health.
These substances persist in the environment and are particularly dangerous if burned. Furthermore, PVC in itself is a rigid material and to soften it, phthalate plasticizers are used, which are also responsible for important health pathologies.
PU is a better material than PVC as far as the finished product is concerned, but it is still a derivative of fossil fuels and its production involves various toxic substances such as dimethylformamide.
What is the carbon footprint of real leather compared to synthetic leather?
In reality, both types of leather have a significant impact on the environment but differ in terms of CO2e emissions (equivalent carbon dioxide): real leather has a much higher carbon footprint than synthetic leather.
Most of the greenhouse gas emissions from real leather derive from the breeding of animals, which, however, are not bred exclusively for the fashion industry, but generally for food purposes, therefore the load of emissions induced into the atmosphere also affects this last sector.
For the production of synthetic leather, the emissions are much lower as fewer resources are needed but, in any case, we must not forget that we are talking about plastic materials deriving from petroleum and other fossil fuels which obviously have a poor sustainability perspective and a negative environmental impact.
Leather tanning is considered the least sustainable and most harmful phase for the planet, as it is based on an enormous water consumption (around 240 liters per 1 square meter of leather) together with the use of chemicals, at the end of the process, first in the rivers and then in the seas causing immense damage to the fish fauna.
As far as Italy is concerned, the UNIC (Unione Nazionale Industria Conciaria) sustainability reports show that the Italian tanning industry has committed itself to reducing its water footprint over the last 20 years by using around 15-20% of water less per square meter of leather.
As in the case of the carbon footprint, the water footprint for the synthetic leather production process also has a lower value because a much smaller amount of water is used.
The life cycle of materials
In terms of durability, there is no doubt that real leather beats synthetic leather. High quality real leather products can last many years, if not even a lifetime.
Conversely, synthetic leather has low resistance and over time, it begins to break into many small fragments, becoming unusable within 2 or 3 years.
This leads us to replace the product by buying a new one, thus increasing the volume of waste in landfills.
Unlike synthetic leather, real leather can be repaired, refurbished and reused.
Both real leather and synthetic leather are treated with chemical compounds which make their biodegradation very slow.
Between the two materials, however, natural leather biodegrades more easily in landfills at the end of its life cycle as it is composed of organic material and not plastic materials such as synthetic leather.
If, instead of being placed in landfills, real leather is burned, then the consequences of chrome tanning become dangerous as combustion releases extremely toxic hexavalent chromium into the atmosphere.
The "Nothing to hide" study carried out by LHCA (Leather and Hide Council of America), estimated that at the end of 2020 a single cowhide disposed of as waste generates greenhouse gas emissions equal to approximately 22.3 kg of CO2e (carbon dioxide equivalent), while those produced by the tanning processes amount to about 4.6 kg of CO2e.
It therefore reduces about 80% of emissions. LCHA has also estimated that currently around 55% of the world's total supply of bovine hides ends up in the hide value chain, with the remaining 45% going to waste.
In this sense, let's say that the processing of real leather allows for the recovery of waste that would otherwise end up in landfills.
Synthetic leather does not decompose easily in landfills as it is made up of plastic material and, like all plastic materials, it can take several hundred years to disintegrate.
During this time it breaks down into ever smaller pieces called microplastics, simultaneously releasing toxic chemicals.
What to buy to make the most sustainable choice
Sustainability, as we have seen, is a concept that encompasses a multitude of aspects. Which type of leather is actually "more sustainable" depends very much on our scale of priorities, that is, on which aspects of that multitude are most important to us.
Surely, however, a sustainable choice on our part cannot ignore the ease of disposal of a product once it becomes waste.
By virtue of this consideration and with a view to "zero waste", it is generally good to prefer products made of easily biodegradable materials or which are made from "waste materials" such as, for example, real leather for industry meat food.
In this sense, as long as this industry is as active as it is today, there is an advantage in working with real leather as nothing of the animal is thrown away and as its life cycle is much longer than the alternatives.
Obviously, it is better to choose a vegetable tanned leather rather than a chrome tanned one.
Another sustainable choice we can make is plant-based leatherette.
Although not yet widely consumed, this new type of leather, which exploits waste materials deriving from other industries (for example cactus, pineapple leaves, apple waste and mycelium), has the advantage of being easily biodegradable despite its durability.
Always thinking in terms of zero waste, another sustainable option is to choose products made from existing materials.
Although the realization of the product involves a certain consumption of resources, the advantage of using an existing material again is that of keeping it away from the landfill for as long as possible or even that of removing it from the environment as "waste", an example of which they are products made from plastic recovered from the oceans.