You have to follow the local regulations, which may possibly depend on disposal volumes. It is an option to lobby to have them changed or to move your location. You have no other legal options.
The main chemical used in rapid fixers is also used in swimming pools. Various silver compounds were used as a wound disinfectant before antibiotics. Beyond normal precautions, as written in the product information, don't worry about the standard chemistry - just keep yourself out of trouble by following the local rules.
Good point about selenium toner, and a few other less common toners. These tend to be more unpleasant than the regular chemistries. Don't try evaporating these toners out, as the dust will be more problematic than the liquids. However, do note that selenium toners can be used, with replenishment and filtration, for a very long time.