Cobalt is a heavy metal. So the simple fact that some horses are returning very high levels (to put it mildly) should be a concern to anyone who has the horses welfare as a priority.
I don't agree with Jack's statement that the NSW stewards haven't done adequate tests on cobalt (if I have miss quoted you Jack I apologise). I am happy with the way the NSW stewards are working on the problem. Having said that I fully agree with Jack's comment regarding the improvement of some horses.