The old stuff (PCBs and PBBs) definitely had health (and environmental) risks. PCBs are famous, and PBBs are in the EU RoHS, so I'd consider them comparable to lead solder in badness at a first glance (not horrible, but not great). Cancer is pretty hard to prove, but other health effects have had studies (at least for PentaPBDE, nothing for TDCPP (Chlorinated Tris)).
TDCPP might actually be on balance worth using; similarly, I think DDT probably is on balance worthwhile for some applications, and asbestos is still used for some purposes. It's all about tradeoffs, but it is easier to justify a tradeoff when the people paying the costs and receiving the benefits are the same. I get close to zero benefit from fire retardant foam in my couch, probably less than the financial cost of the chemicals.
(I am generally anti whacko unsubstantiated environmentalist/save-the-children activists, but I have some personal experience with PCB contaminated transformers; bleh.)