Fact Sheet: Tanneries – Ranked #4


Estimated DALYs: 1,930,000


What is the industry?


Tanning is a set of processes that turns animal hides into leather appropriate for making a range of consumer products. Tannery processes treat raw animal hides to remove hair and leftover animal parts, stabilize the hides so they do not decompose and then dye or treat them to create a finished product. Products include belts, shoes, clothing, pocketbooks and additional consumer items. These processes are done in many steps using many different types of chemical and mechanical means. Small-scale tanneries are often the source of pollution because of the lack of pollution controls and rudimentary processing.


What are the pollutants?


The top pollutant from tanneries is chromium. Trivalent chromium (the less toxic form) is used in the re-tanning process and is washed off from leather during the dying process. Hexavalent chromium is the top contributor to the burden of disease. Solid waste can also contain animal pathogens, pesticides, and insecticides.


What are the exposure pathways?


The tanning processes use various chemical solutions and create large volumes of wastewater, together with solid waste and sludge. Untreated wastewater can contain acidic and alkaline water, pesticides and insecticides, animal pathogens and most notably, may have very high levels of trivalent or hexavalent chromium. Solid waste can include skins, hides or hair and chromium-contaminated sludge waste, or mixed waste with a combination of all of these.


What are the health risks?


Hexavalent chromium is a known carcinogen that is proven to cause lung cancer from inhalation and is suspected to cause stomach cancer through ingestion.

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