Leather Tanning Is A Highly Polluting Process. It’s Time To End.
- Marina Moore
- Apr 14
- 5 min read
Leather Tanning Is A Highly Polluting Process.
It’s Time To End.
Leather tanning is one of the major industries that flourished worldwide, particularly in India, Bangladesh, China, Pakistan, Turkey, and Brazil. In India, the tannery industries form a significant sector of the economy and are among the nation’s top 10 foreign exchange earners, ranking second in the world for exports, with a value of $3.68 billion in 2020–2022, with more than 2,000 tanneries located in Tamil Nadu, followed by West Bengal, Uttar Pradesh, Punjab, Maharashtra, and Andhra Pradesh.
However, heavy metals are discharged and place a serious threat to public health. The processing of leather from animal hides/skins includes a series of mechanical and chemical operations such as soaking, liming/unhairing, de-liming, bating, pickling, skin degreasing, tanning, post-tanning, and dyeing of raw hides/skins using different types of chemicals.
Organometallic salts of different heavy metals such as chromium (Cr) cadmium (Cd), copper (Cu), lead (Pb), are extensively used as colouring agents and mordant during leather dyeing and in other post-tanning and finishing operations to make the leather suitable for making various leather products such as bags, shoes, and clothing. The tanning process is one of the key steps to produce good leather. Currently, the commonly used material for tanning agent is chromium sulphate. However, in the tanning process, 60% of chrome bonds with the skin, and the rest 40% is discarded along with wastewater. The concentration of tanneries has led to significant environmental and health impacts, as the production of leather often generates large volumes of hazardous waste (Bagla, P. et al: 2021) (Mishra, S.K. et al: 2025) (Zhao, J. et al: 2022).
The Bangladesh economy relies heavily on its leather sector, which employs nearly a million people, including children. The industry is also poisoning many of them and will kill 90% by the time they reach 50.
In today’s world our food is exported from all over the world.
Why, we should be concerned.
Metal contamination in vegetables has become a matter of great concern in many countries. The cultivation of leafy vegetables in tannery effluent contaminated soil results in the transfer of metal contamination to the different parts of plants tissues (stem, root, leaf, etc.) and finally introduced to the human food chain if those plants are consumed (Ahmed, S. et al: 2022). Studies conducted with soils collected from canal sides at the downstream of Hazaribagh tannery area under Bangladesh Dhaka South City Corporation (DSCC) and Keraniganj agricultural area, found that among the metal contents, chromium was the highest in the soil around the industrial zone. The cultivation of leafy vegetables in tannery effluent contaminated soil results in crucial contamination with heavy metals. It was also observed that the leafy vegetables have the high tendency to accumulate heavy metals that is quite alarming for human consumption. Therefore, these vegetables are not suitable for cultivating in tannery effluent contaminated soil.
(Oruko, R. O. et al: 2021), also found exhibiting elevated levels of Cr contamination in effluents and dumpsite soils of two tanneries in Kenya and South Africa during the dry and rainy season of 2018. the results provide scientific insights on the need for both improved effluent management and treatment technologies of tannery wastes, coupled with the strengthening of continuous monitoring and enforcement for compliance of industrial discharges in all countries.
Yet, treated tannery wastewater use standards vary from country to country. The Environmental Protection Agency (EPA) controls the effluent limitations for the tannery in the United States. Similarly, in the European Union, the Urban Wastewater Treatment Directive requires tannery facilities to meet specific discharge standards for pollutants such as total suspended solids (TSS), biological oxygen demand (BOD), and chemical oxygen demand (COD). The EU guidelines for reusing treated wastewater in agriculture recommend that the wastewater contain less than 10 mg/l of BOD and less than 2 mg/l of TSS. However, in India it is set at a different level. The Central Pollution Control Board (CPCB) has established guidelines that specify the quality of treated wastewater that can be reused for different purposes. The treated wastewater can be used for irrigation if it contains less than 30 mg/l of BOD and less than 50 mg/l of TSS. Again in China, the Ministry of Environmental Protection (MEP) the concentrations of pollutants such as TSS, BOD, and COD in tannery wastewater discharge. The MEP’s guidelines for reusing treated wastewater in agriculture recommend that the wastewater contain less than 30 mg/l of BOD and less than 10 mg/l of TSS (Bhardwaj, A. et al 2023).
The contamination of water is the consequence of both man-made and natural actions. Chemicals have contaminated water bodies worldwide in different industries, including textiles, tanning, and dyeing, which are highly toxic. Due to their negative consequences such as severe health risks, they produce environmental contaminants, and their toxicity is a major global issue.
The UN World Water Development Report has indicated that the global water crisis and severe water shortages are mainly due to the decline in freshwater availability and water quality degradation. By 2030, 40% of the world’s population is predicted to lack access to fresh water. Safe drinking water is essential for humans to maintain a healthy body, ecosystem, and economy. Yet around 29% of the worldwide inhabitants rely on contaminated water sources for drinking. (UN-Water 2021).
Ahmed, S. Fatema-Tuj-Zohra, Meem Muhtasim Mahdi, Md. Nurnabi, Md. Zahangir Alam, Tasrina Rabia Choudhury. (2022) “Health risk assessment for heavy metal accumulation in leafy vegetables grown on tannery effluent contaminated soil”. Toxicology Reports, Volume 9, Pages 346-355. https://www.sciencedirect.com/science/article/pii/S2214750022000373?via%3Dihub
Bagla, P., Kumar, K., Sharma, N. Sharma, R. (2021) “Multivariate Analysis of Water Quality of Ganga River”. Journal of the Institution of Engineers (India), Series B, Volume 102, Pages 539-549. https://link.springer.com/article/10.1007/s40031-021-00555-z#citeas
Bhardwaj, A. Kumar, S. Sing, D. (2023) “Tannery effluent treatment and its environmental impact: a review of current practices and emerging technologies”.
Water Quality Research Journal, Volume 58, Article number 2. https://www.researchgate.net/publication/370646001_Tannery_effluent_treatment_and_its_environmental_impact_a_review_of_current_practices_and_emerging_technologies
Mishra, S.K. Kumar, V. Kumar, J. Nath Jha, D. Alam, A. Ramrao Thakur, V. Verma, S. K. Singh, U. Kumar Das, B. (2025) “Water quality assessment of river Ganga, India using water quality index and multivariate statistical techniques”. Environmental Monitoring and Assessment, Volume 197, Article Number 240. https://doi.org/10.1007/s10661-025-13669-4
Oruko, R. O. Edokpayi, J. N. Msagati, T. A. M. Tavengwa, N. T. Ogola, H. J. O,. Ijoma, G. Odiyo, J. O. (2021) “Investigating the chromium status, heavy metal contamination, and ecological risk assessment via tannery waste disposal in sub-Saharan Africa (Kenya and South Africa)”. Environmental Science and Pollution Research.
UN-Water (2021) “WHO/UNICEF Joint Monitoring Program for Water Supply, Sanitation and Hygiene (JMP) - Progress on household drinking water, sanitation and hygiene 2000 – 2020”. WHO/UNICEF Joint Monitoring Program for Water Supply, Sanitation and Hygiene (JMP) - Progress on household drinking water, sanitation and hygiene 2000 - 2020 | UN-Water
Zhao, J. Wu, Q. Tang, Y. Zhou, J. Guo, H. (2022) “Tannery wastewater treatment: conventional and promising processes, an updated 20-year review”. Journal of leather Science and Engineering, Volume 4, Article number: 10. https://jlse.springeropen.com/articles/10.1186/s42825-022-00082-7
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