That simply isn’t true. With B&W the only aspect of film development that poses environmental worries is the silver suspended in exhausted fixer. You’d have to

That simply isn’t true. With B&W the only aspect of film development that poses environmental worries is the silver suspended in exhausted fixer. You’d have to be doing much more exotic work to require more precautions. Things like Selenium toning, perchlorate (ugh, nasty stuff) activators, potassium ferricyanide, etc. need more care but the processes that use those things are really rare these days. Developer compounds break down rapidly and stop bath is just a mild acidic solution, usually the equivalent of vinegar. With the exception of the fixer, home darkroom work is of no environmental consequence. Kodak, Fuji, and Agfa had gotten chemical safety figured out by the 90s. The last thing I remember being a problem was the stabilizers made from formulin (related to formaldehyde) but that was stopped in the late 90s. Think VPS was the last film that required it for the best archival performance. Large quantities of developer/stop/bleach were also able to be disposed of once the ph had been neutralized. The only disposal service I remember with the labs I worked in was the silver recovery for the fixer. As far as manufacturing films and papers goes I’m less certain. I do know that Kodak had been trimming some materials from their catalog that used dangerous materials through the 90s. They discontinued a warm tone paper that was loved by many in the early 2000s. It used cadmium as part of the emulsion chemistry. And while it didn’t pose any risk to people using the paper, manufacturing it certainly did. I’m sure that the big three film manufacturers had managed to minimize the use of dangerous materials as awareness and regulations spread. Can’t be as sure about the eastern European manufacturers though.