The sports scientist responsible for the World Anti-Doping Agency’s (Wada) Salbutamol regulations wrote in support of Chris Froome during his recent case. Ken Fitch says that he made a ‘terrible blunder’ and has been pressing Wada to change its rules for years.

Froome provided a urine sample after stage 18 of last year’s Vuelta a Espana that contained 2,000 ng/ml of Salbutamol.

A sample over 1000 ng/ml triggers an abnormal finding, but Fitch, who works at the School of Human Sciences at the University of Western Australia, told The Times that the threshold resulted from tests conducted on swimmers.

He points out that while swimmers finish their efforts with a full bladder, cyclists are often dehydrated after riding for hours and thus their urine is more highly concentrated.

“I’ll admit I made a terrible blunder,” he said.

Fitch wrote in support of Froome and previously sided with Alessandro Petacchi after he produced an abnormal reading of Salbutamol in a sample at the 2007 Giro d’Italia. The Italian sprinter ended up serving a one-year ban.

Froome was cleared earlier this week with world cycling's governing body, the UCI, saying that Wada had told it that in light of "the specific facts of the case" it accepted Froome had not committed an anti-doping rule violation.

Many are keen to see the finer detail of the case. Asked whether Team Sky would be releasing any further detail on the ruling, Sir Dave Brailsford said that the onus to do so lies with Wada and the UCI.

“The shadow of doubt shouldn’t exist if we trust in our authorities,” he told the Guardian. “The people who made the decision were Wada and the UCI, not Team Sky. I think that’s where the information about how that decision was made should come from.”

UCI president, David Lappartient, said: “An international federation such as the UCI has to follow the World Anti-Doping Agency. They are the experts on this and their experts finally decided that this case was not an anti-doping rule violation so we had to follow the decision from Wada.”

Speaking shortly after the decision was announced, Wada’s head of science Dr Oliver Rabin said that he had been “well aware of salbutamol’s variability”, adding: “That is why an adverse finding only opens the door to further study – it’s not an automatic sanction.”

Outlining the specific elements, he said. “First, there was a very significant increase in dosage in the preceding days [but still within legal limits]. Second, he was being treated for an infection. And then there was the physiological impact of the event and other factors, such as dietary supplements and so on.

“Given all of this we decided an excretion study was impossible and the finding was not inconsistent with therapeutic dosages. It’s not a unique case but because it was Froome, a sporting celebrity, and it was put in the limelight, it appears to be unique. For now, we have no reason to question the rules. We can see no reason that previous cases have not been handled fairly.”