Though I no longer have the citation, tonnes of dichromate are dumped via industrial use to the environment daily. A fraction of a gram used to make a gum print is inconsequential by comparison. And, much of the waste water used by a hobbyist can be collected and reused, then the chrome salt converted to a less toxic trivalent chromium form before being disposed of as a precipitated solid waste.

I'm not sure if it is still made, but IIRC, Edwal tray cleaner was essentially dichromate solution and might be easier to obtain in that form in some countries.