I suppose I didn't consider the amount of additives in current leathers. What are the production costs (environmental, rather than monetary) of the waterproofin

I suppose I didn't consider the amount of additives in current leathers. What are the production costs (environmental, rather than monetary) of the waterproofing? It would be a shame to have something that has very limited impact on the environment being used as a substitute for leather, only to find out the post processing is also quite damaging.