Following reports that Russian athletes inhaled xenon to boost their performance at the
The amendment was prompted by what WADA President Sir Craig Reedie called "significant and pressing topics" discussed at a meeting last spring.
Enforcement on other newly banned substances -- including the gas argon -- are also set to begin on Monday.
Last winter, a report from a German broadcaster claimed that Russian team members had been inhaling xenon dating back to the 2004 Athens Olympics.
Russian sports officials subsequently denied that its team had used xenon.