10/28/2011 01:58 EDT | Updated 12/28/2011 05:12 EST

Canadian wakeboard medallist tests positive for banned substance at Pan Am Games

GUADALAJARA, Mexico - A failed drug test has cost Canadian wakeboarder Aaron Rathy his silver medal at the Pan American Games.

Games officials say the 23-year-old from Nanaimo, B.C., tested positive for the stimulant methylhexaneamine — the first doping offence at these multisport Games.

The 2009 world wakeboard champion blamed a supplement, which bills itself as a fat-burner, for the positive test.

"I'd like to apologize to the Canadian Olympic Committee and coaching staff," Rathy said in a statement issued by Water Ski and Wakeboard Canada.

"I am deeply sorry, and was completely unaware of the banned substance in the OxyElite Pro I had taken. I purchased the product at a GNC health food store, and to my knowledge was all safe to take. It was a privilege to compete for Team Canada at the Pan-Am Games and it was never my intention to cause any damage or inconvenience."

In November 2010, Canada's doping watchdog warned athletes that supplements containing methylhexaneamine were "widely available in the Canadian market and have been the source of many doping violations worldwide over the last year."

"We keep telling athletes over and over and over again, even if it's not methylhexaneamine, athletes should be extremely cautious about taking supplements," Rosemary Pitfield of the Canadian Centre for Ethics in Sport said in an interview.

"Because quite often they do not have everything on the label that they contain."

The COC said it was first advised Tuesday of the doping result. The Pan American Sport Organization subsequently convened a Disciplinary Commission Panel hearing Friday that resulted in a decision to disqualify Rathy and have him return his medal.

"The athlete is co-operating fully, has accepted responsibility, and apologized for the inadvertent use of a banned substance," the Canadian Olympic Committee said in a statement.

"While the COC does not condone the use of banned substances, we are supporting the athlete's right to a fair hearing and due process."

Rathy won his medal last Saturday in Chapala, Mexico.

"So stoked on getting a Silver medal at Pan-Am Games in Mexico!!," he tweeted two days later.

A Canadian team official said Friday that Rathy had left Mexico.

The issue of positive drug tests is referenced on the website of USPlabs, which manufactures Oxy Elite Pro.

A question on the site FAQ asks: "I am a drug-tested athlete, can I use Oxy Elite Pro?"

Answer: "While none of our products contain illegal compounds (as defined above in previous question), it depends upon what your governing body is testing for. The NCAA, for example, prohibits its student athletes from using any stimulant, and this is true for the World Anti-Doping Association as well. As with any dietary supplement, consult with your representative from the testing agency to ensure your supplementation is within guidelines. We strongly recommend you do not use any dietary supplement before getting clearance from your governing body. If you cannot obtain clearance, do not use the product."

Pitfield said methylhexaneamine can be found in both nutritional supplements and sport drinks.

"We do know we are seeing it more prevalently," she said from Ottawa.

"Sometimes the labelling on the supplement may have not exactly have methylhexaneamine and that's also tripping up the athlete. The derivative that it has in the supplement is what is being listed on the label — the byproduct is methylhexaneamine," she added.

The GNC website offers OxyElite Pro on sale: 180 capsules for US$76.99.