One of the largest contributors to pollution during the French Revolution was the work of tanneries, which converted what is essentially animal skin, into leather goods. First the hide was immersed in an alkaline lime and water solution for up to 3 weeks, then it was brought out and shaved for both the hair on one side of the hide and the dissolved fat referred to as “sinew” on the other side. Once this process had been complete, dog and bird feces were mixed with hot water and human urine to create a bacterial cocktail which would work together to soften the hide and help it absorb dye. All of these components were dumped into local water sources once they had served their purpose which made living around them nearly impossible, with many people developing ulcerative lesions upon their throats when around these ingredients for extended periods of time