Storage and subsequent reanalysis of samples has resulted in numerous positive cases involving athletes at the Olympic Games since being introduced at Athens 2004.

The use of the latest scientific methods has enabled the detection of banned substances in samples.

A new test, developed in 2016 following assistance by former Moscow Laboratory director Grigory Rodchenkov, detected the use of steroids over a period of months rather than days.

This was seen as key to the rise in positive tests in the Beijing 2008 and London 2012 retests.

Five athletes were sanctioned from Athens 2004 retests, while 65 cases emerged from Beijing 2008 retests.

Currently 60 athletes have been caught in London 2012 retests, according to IOC statistics, with the process set to conclude later this year due to the eight-year statute of limitations expiring.

Samples taken from the Rio 2016 Olympic Games will have a 10-year statute of limitations.

Of the Continental Games organisers which responded to insidethegames, Panam Sports store samples for the longest period.

Panam Sports said they are retained for a four-year cycle.

A World Anti-Doping Agency (WADA) Independent Observer (IO) Report from the Incheon 2014 Asian Games called for the OCA to establish appropriate policies for the retention of samples for possible further analysis.

While stating samples should be ideally retained for 10 years, the IO team recommended retaining certain samples, identified through a risk assessment, for at least four years should costs prove prohibitive.

The OCA’s anti-doping rules say samples may be collected and stored for future analysis.

The WADA IO Report from last year’s Asian Games, held in Jakarta and Palembang, found the OCA had not put a plan in place.

"When asked about their plan for sample storage, the OCA indicated they have no intention to keep samples longer than the three-month period identified in the laboratory contract,” the report reads.

"ISTI Article 4.7.3 mandates that a retention and re-analysis strategy be put in place.

"This requirement was also raised in the last IO report and the IO Team further reminds the OCA to develop such a strategy.

“While the OCA mentioned that, in the past, they had reached out to relevant International Federations (IFs) to see whether they were interested in keeping certain samples, this was not done for these Games.

“The strategy developed by the OCA should also consider the ability for samples to be transferred to applicable IFs or National Anti-Doping Agencies (NADOs) for long-term storage.”

insidethegames has asked the OCA for a comment on its current policy and whether the organisation could commit to collecting and storing samples at future editions of the Games.

European Olympic Committees (EOC) medical commission head Klaus Steinbach confirmed earlier this summer that samples from the European Games in Minsk would be frozen for one-and-a-half years.

This would replicate the same policy used for the European Games in Baku in 2015, where samples were destroyed after the Rio 2016 Olympic Games.

The EOC told insidethegames the organisation has not established any kind of ongoing reanalysis programme, with IFs and NADOs instead entrusted to conduct their own retesting process.

The EOC claim this avoids duplicating storage and reanalysis costs.

Both IFs, NADOs, the International Olympic Committee (IOC) and International Testing Agency (ITA) were contacted immediately after the Games in Minsk to determine whether they wished for samples to be transferred to their organisations, the EOC said.

"While, in accordance with both the World Anti-Doping Code and the EOC Anti-Doping rules, any adverse analytical finding from a sample taken at the European Games, whether immediately analysed or later reanalysed, should lead to results management process by the EOC, it is the IFs and NADOs who have the facilities and an ongoing interest in reanalysis, in particular the IFs as they would be the official sanctioning body in terms of suspensions and bans,” an EOC spokesperson told insidethegames.

"For these reasons, and in order not to duplicate storage and reanalysis costs, which are extremely costly, the EOC has not put in place any kind of ongoing reanalysis programme to reanalyse the samples at a future date, entrusting this to the IFs and those NADOs that may have an interest.

"For the same reasons the EOC does not currently have a structured research programme in relation to samples.

"Again, this would simply duplicate work that the IFs generally do anyway.

"Sample storage is extremely expensive and the above policy aims to avoid duplicating storage and reanalysis costs, given that it will be the IFs who will inform the EOC should they come up with any adverse analytical findings in the course of time, on the strength of which the EOC will then reassign rankings for the event concerned.”

The EOC highlighted the example of canoe sprint from the Baku 2015 European Games, where the International Canoe Federation had informed them of an anti-doping rule violation from Hungarian athlete Miklós Dudás in 2016.

Dudas had initially won the men’s K1 200 metres competition at Baku 2015.

A reallocation ceremony took place at Minsk 2019, where Petter Menning of Sweden was upgraded to gold and Britain’s Ed McKeever was promoted to silver.

Initial fourth place finishers Aleksejs Rumjancevs of Latvia and Serbia’s Marko Dragosavljevic won joint bronze.

The WADA IO Report from the Toronto 2015 Pan American Games had encouraged Panam Sports to "carefully consider the identification of specific samples for storage and reanalysis at a later stage".

It followed a total of 20 positive tests from the Games in the Canadian city.

Panam Sports insisted a “sophisticated anti-doping system” was in place for the recently concluded Pan American Games in Lima, where two athletes were sanctioned for failed tests.

Four further athletes were confirmed to have been ruled out of the Games prior to competing.

Panam Sports say their anti-doping programme included 40 per cent of tests out of competition, with the remaining 60 per cent consisting of in competition tests.

Samples will be stored for retesting until Santiago 2023.

"As in the past, samples taken of athletes during the Pan American Games are usually stored for a minimum of four years, at least through to the next Pan American Games,” the Panam Sports Medical Commission told insidethegames.

"Panam Sports has the option to retain samples for up to 10 years if the organisation has the sufficient funds and desire to do so.

"Likewise, individual IFs - such as those with a high risk of or past doping concerns - can request that samples be stored longer than the four-year minimum.

"Then it would fall on the IF to bear the costs of storing said samples."

insidethegames has contacted the Association of National Olympic Committees of Africa (ANOCA) for details of the organisation’s storage and retesting processes for previous and the upcoming African Games.

WADA has encouraged major event organisers (MEOs) to store samples for as a long as possible, with a priority placed on high risk sports and those from countries with a history of doping offences.

"The storage and further analysis of samples has proven to be a strong deterrence and detection tool,” a WADA spokesperson told insidethegames.

"As detection science advances, this tool has enabled those ADOs that used it to protect the results of their events and ensured that those athletes who cheated are brought to justice.

"Under the World Anti-Doping Code’s statute of limitations, analysis on stored samples can occur within 10 years of the sample being collected.

"The IOC, and other MEOs, have shown the importance and success of storing samples and conducting further analysis.

"For example, samples collected and re-analysed from the Beijing 2008 and London 2012 Olympic Games, to date have resulted in more than 100 athletes returning adverse analytical findings with many doping cheats having their results erased and corresponding medals reallocated.

"WADA would strongly encourage all MEOs to store samples for as long as possible, prioritising samples taken from athletes competing in high-risk sports, from countries with a doping history, on the recommendation of the WADA-accredited laboratory that originally analysed the samples or where other intelligence may be available, such as the athlete biological passport."

To read the full blog on sample storage, click here.