A. There is good and there is bad. The good part is rubber mulch is made from recycled materials, waste that would otherwise be recycled in other products or put in a landfill. Too much of it goes into available landfills already.
Recycling includes use in new tire manufacturing, rubberized asphalt, energy production, and burned as a fuel. It is proposed that use of shredded tires poses no health concerns but there are objections because of their heavy metal content and possible source of pollutants. It has been used in children’s playgrounds where it has been a source of many concerns. The problem is basically over the costs associated with recycling.
Personally I don’t like it as a mulch for plants, particularly food plants. I would not use it for that. I think there are other ways of recycling it without putting it in close proximity to humans, animals and plants. I don’t think it has a place in landscapes.