Chrome or chrome free leather? What to choose? And what is the environmental impact?

Over the past years, there has been considerable debate about the environmental impact of chromium as a tanning material. 

Chrome tanned leather is tanned with trivalent chromium sulphate (non-toxic), which occurs naturally in the environment and which is also present in foodstuffs and is a necessary nutrient for the human body. Chrome tanned leathers are more resistant and softer than those produced by other tanning processes. Vegetable tanning agents like mimosa (bark), quebracho (wood) or tara (fruit) are used for vegetable tanning. Synthetic tanning agents are produced synthetically, i.e., not found naturally in the environment. As a rule, synthetic tanning agents are not used as the sole tanning agents, but in conjunction with vegetable or chrome tanning agents.

Comparing chrome tanning and chrome free tanning and considering the environmental impact, you will have to consider several advantages and disadvantages.

Water, energy and tannage consumption

Nowadays, tanneries are returning water to rivers in a purer state than when it was first extracted. 
To protect the environment, the majority of raw hides arrive fresh and ready for processing at the tanneries, which drastically reduces the release of salt into the discharge water system. Salt is generally seen as an inexpensive way of preserving raw hides. In accordance with local authority standards, the tanneries have their own wastewater treatment plants as well as waste disposal sites for tanning waste. Regular inspections are conducted to ensure that the quality and environmental standards are maintained at all times.

In production, chrome tanned leather is more environmentally sustainable, as the water and energy consumption of vegetable tanning is 35% higher. In addition, the environmental impact on waste water (biological and organic molecules are less degradable), sludge and waste product is higher when you use vegetable tannage. Apart from this, the use of vegetable tannage is 10 times higher than for chrome tanning. So, in production vegetable tanning has no ecological advantage compared to standard chrome leather. Although chrome has been treated with much distrust, there has been no scientific evidence for the actual negative impact on the environment or human health to this day. A further factor is that synthetic and vegetable tanning is more expensive than chrome tanning, as the tanning process is more complex. Hides shrink when you use vegetable or synthetic tanning.

Recent studies reveal that an average tannery uses approximately 160 litres of fresh water, generates 5 kg of organic waste and uses around 8 kg of CO2 to produce 1 kg of grain leather. Comparing water consumption in the leather industry with other industries, 500 litres are used in the bleaching, dyeing, printing and finishing of one pair of jeans. However there is still room for improvement in the reduction of waste, pollution, energy and the consumption of fresh water within the leather industry.

Recycling

In terms of recycling, however, chromium does have a disadvantage, as it is environmentally persistent. But on the other hand, when the Otzi mummy from 3300 BC was found, parts of his vegetable tanned leather clothes were intact and had not been naturally dissolved. Normally, synthetic or vegetable tanned leather without finish does dissolve in nature if it is shredded into very small pieces (like sawdust).
In the context of recycling, tanning provides the perfect recycling loop. Tanners use the hides and skins which are waste products from the meat industry. Leather industry waste can then be used for the shoe industry or as a fertiliser to encourage the growth of fodder crops to feed the animals which provide the meat industry with its raw material. This is a very “green” recycling process. The environmental impact of the disposing of all the hides as waste would be significantly larger than adding up all current tannery pollution in the world. Furthermore, when comparing leather to textile, the life span is significantly longer. 

Despite the fact that the leather industry is one of the oldest trades and leather probably may be considered the first example of waste recycling (recycling of animal skins), tanneries have been brought into disrepute for their effect on the environment time and again. However, the restrictions on environmentally harmful emissions were not introduced on account of the leather industry, but are restrictions applicable to all industrial sectors. Europe, especially Central Europe, has the lowest limit levels in absolute terms for environmental emissions. Other countries may well have similarly stringent laws, but not all are as consistent in enforcing them.

Taking the above facts into consideration, it cannot be clearly concluded that one or the other type of tanning has an ecological advantage over the other.