I'll revise my list of toxicity to include Pyro, Selenium, Mercury and Cadmium not necessarily in that order. They are all nasty!
I agree with Bill, mercury is not to be trifled with. As part of a large team at Kodak, we worked hard to eliminate Mercury and Cadmium from films and papers. I was on the color paper team. We also virtually eliminated Mercury. A tiny amount of mercury remained in one layer of color paper.