(AP) -- Questions over the integrity of sample-collection bottles led to frustration from athletes this year at Winter Olympics, including two who tightened their bottles so tightly, they cracked the caps.
Independent observers released their report Thursday about the anti-doping operation in Pyeongchang.
In all, there were 3,189 tests conducted that led to 15 positive tests, six of which led to anti-doping rules violations that were upheld. Two of those involved Russian curler Alexander Krushelnitsky , who gave back his bronze medal after testing positive for meldonium.
Observers said doubts about the credibility of the anti-doping program stemming from the Russian scandal at the Sochi Games in 2014 led to behavior that "revealed underlying feelings which included skepticism, doubt and fears."
Among the athletes' top concerns was the integrity of the urine-collection bottles , which were found to be susceptible to being opened without leaving any evidence. Media reports about the flaw circulated only weeks before the Olympics started. A different style bottle was used in Pyeongchang, but the confusion "created an atmosphere of suspicion," and two athletes broke the bottles in an attempt to screw on the lids tight enough to ensure no one could tamper with their samples.
The observers reported hearing steady talk about the findings from the Sochi Games . Multiple investigations revealed that Russia ran a state-sponsored program in which athletes' dirty urine samples were surreptitiously swapped with clean ones. Russia's Olympic delegation was banned from Pyeongchang, but 168 Russian athletes were allowed to compete as "Olympic Athletes from Russia."
Other flaws in the system:
-- Athletes "resented" being forced into out-of-competition testing on the day they were competing, before the competition. Some spent long hours waiting to be tested because multiple athletes had been called for out-of-competition testing and there weren't enough rooms available to take samples.
-- Athletes felt therapeutic use exemptions -- permission to use banned substances for existing medical conditions -- were being abused.
-- Athlete support personnel acted aggressively and often tainted the opinions of other athletes in certain areas, sometimes because they were ill informed about the testing regimen.
The observers said that given the challenges the Sochi scandal brought, there were "generally satisfied with the end-to-end doping control arrangements put in place for the Games."
But Sochi was on almost everyone's mind.
"The trust in the system and the chain of custody of samples was challenged, and the impact of the Sochi experience could not be dissociated from the perceptions of the Olympic athletes toward anti-doping procedures," the report said.