The final test results for the Queensland horses found to have cobalt irregularities should be available this week.

Six harness racing and thoroughbred trainers are facing investigation after excessive cobalt levels were found in their horses.

Due to a large number of tests to be carried out from all states there has been a delay in the results being returned to Racing Queensland.

The situation has also been muddied by the standing down last month of RQ's chief integrity officer Wade Birch during an unrelated investigation into greyhound racing.

Chief steward Allan Reardon has been put in charge of the cobalt investigation pending Birch's return.

Cobalt occurs naturally in horses but in higher quantities can generate more red blood cells to carry oxygen through the body.

It can allow a horse to perform at a peak level for longer without the onset of fatigue.

Scientific advice is that it can be toxic in high levels.

Australian racing rules now dictate if cobalt is detected at a concentration above 200 micrograms per litre in urine in a race-day sample it is a prohibited substance.

Samples are first screened in Queensland and then any needing further examination are passed on to Perth.

If samples fail the Perth tests for the cobalt threshold, there are further tests in either Hong Kong or Sydney.

Newcastle trainer Darren Smith will learn his fate this week after being found guilty of more than 40 charges relating to cobalt in his horses.

Sam Kavanagh will also front a Racing NSW inquiry into high levels returned by Gosford Cup winner Midsummer Sun who was also found to have caffeine in his system.

A Racing Victoria investigation into four stables is continuing with no time frame set for its conclusion.

Peter Moody, Mark Kavanagh, Danny O'Brien and the Lee and Shannon Hope partnership are the trainers involved in the RV investigation.