Actually, I might point out that the pollution to make and reclaim a digital sensor is far greater than that to make a run of film and process it simply due to the nature of the chemicals used. These include Arsenic, Selenium, Lead and Mercury to name a few.
And, the biggest pollution world wide is Agriculture and Aquaculture. These spread pesticides and disease from the cultivation and growth of plants and animals. And, they consume the most fresh water and put out the most polluted runoff in all countries. This is just an FYI.