Leather is the most commonly used material in the manufacture of shoes. It is natural, breathable, comfortable and looks good, but is also costly to produce in terms of its environmental impacts and damage to the health of the workers producing it. The environmental impact of leather is associated with the rearing of the livestock, the use of polluting chemicals including chromium a toxic heavy metal in the tanning process and air pollution including hydrogen sulphide during dehairing, ammonia during deliming and solvent vapours. The chemicals used in tanning leather make tanneries very unpleasant and hazardous places to work. Those living nearby are also affected by the hazardous chemicals. The Centres for Disease Control and Prevention in the US found that there was a five times higher incidence of leukaemia among residents in an area near a tannery in Kentucky. Lung cancer in tannery workers is also associated with their exposure to arsenic a chemical used in the tanning process.
Vegetable tanned leather is a much more environmentally friendly option than conventional leather but it is also more expensive and does still have a significant environmental impact caused by the rearing of livestock. Vegans, vegetarians and those concerned with animal rights usually do not wear leather shoes because they believe that it is cruel to wear animal skins. Over the years there have been a variety of alternatives to leather shoes produced for the vegetarian and vegan market including vegan microfiber which is similar to suede in appearance and pleather, Naugahyde, Durabuck, NuSuede, Hydrolite, all of which are synthetic. The problem with these synthetic alternatives is that their manufacture is energy intensive and they do not easily biodegrade so are problematic to dispose of once their useful life is over.
So what are the alternatives?
Fish leather is made using the skin of fish which is a by product of the commercial fish industry which is in abundant supply making it a really sustainable material. It is tanned by soaking the hide to remove the flesh before strengthening and odour removal. It is then usually dyed with vegetable dyes. Fish skins are relatively small (compared to cow hides) so are particularly useful for smaller items like hand made shoes, gloves and purses. They are even stronger and more durable than conventional leather made from cow hide. Because the tanning process for fish skin does not need to remove hair (only scales), it is much simpler and therefore does not need the polluting chemicals used in traditional tanning.
In the past cork has commonly been used in the heels of shoes but now a very thin piece of cork also known as cork leather or cork fabric is also used as a natural and eco friendly alternative to leather. It is hard wearing and durable and has even been used to make an alternative to a leather jacket. Cork is the bark of the Cork Oak tree (Quercus Suber) a native species of Portugal. Its removal does not harm the tree and the tree will grow a new layer to replace the harvested cork making it a renewable and sustainable resource.
Ocean leather is a little known natural alternative to leather that is made from kelp. This product is however at the early stages of development and very rarely used. Other natural and eco friendly shoes are made using organic fabrics such as hemp and cotton. They are grown without the use of pesticides and are dyed with eco friendly dyes that do not contain heavy metals, they do not however have the hard wearing properties and strength of leather.
Whilst there are currently a variety of usable alternatives, the hunt is still on for the perfect natural and eco friendly alternative to leather. The perfect alternative to leather would need to be strong, breathable, durable, look great and be able to be produced cost effectively on a large scale.