Racing NSW doesn't have an established threshold for cobalt but the levels returned by one of trainer Darren Smith's racehorses has far exceeded any calculations.

Testarhythm was found to have a reading 30 times that of the 200ng/mL threshold introduced by Victorian authorities.

The gelding's A sample was 6470ng/mL and the B sample came back at 6200ng/mL.

Smith, who fronted an inquiry on Friday, stood down from training in May after tests carried out on 13 horses in his stable returned positive results to cobalt chloride.

The trainer was interviewed by stewards on April 29 when they were alerted to a high level in one of the horses.

He subsequently admitted he had obtained a bottle of what he understood to be cobalt from disqualified harness racing trainer Shannon Wonson but had thrown it away once it was finished.

Smith said Wonson, who was working as a farrier, was treating a show horse belonging to the trainer's daughter, gave him the bottle and told him it was a blood booster.

"He gave me one bottle, and I used it to help the horses with their recovery after racing," Smith said.

He said he had given it to Testarhythm after a gallop, four days before the gelding won the Listed Ortensia Stakes at Scone on May 17.

Counsel for Smith, Paul O'Sullivan, argued on Friday that because there was no threshold there could be no case.

But Racing NSW said cobalt came under under the rule which prohibits Hypoxia Inducible Factor stabilisers.

"There is a raft of papers which slot cobalt into the category of hypoxia stabiliser," Racing NSW chief veterinarian Craig Suann said.

Professor David Hibbert is involved in analysing statistics to establish a cobalt threshold in NSW. Racing Victoria has gone ahead without such data, placing a 220ng/mL limit.

Hibbert's statistics are based on a scale of 50ng/mL, with Testarhythm's finding way off the scale.

"It is so huge I can't even give you a number for it," he said.

Chief steward Ray Murrihy said Racing NSW believed the research was necessary because small amounts of cobalt were found in therapeutic products including Vitamin B12.

In humans it has been used to treat anaemia to boost red cell production.

Cobalt is on the World Anti Doping Agency's banned list.

Sixteen samples taken from 13 of Smith's horses have been found to have a high concentration of cobalt.

The hearing was adjourned to allow O'Sullivan to review the evidence so far.