The World Anti-Doping Agency wants to simplify and, at the same time, refine the instructions given to laboratories for interpreting certain results that may appear to be positive doping tests without necessarily involving the intentional use of a Prohibited Substance. The organisation has opened a consultation until 14 September on three new Technical Letters that will consolidate 22 of the 25 currently in force.
The changes affect particularly sensitive situations for athletes, such as food or pharmaceutical contamination, compounds that may form within a urine sample after collection, or results caused by interactions with medications that are permitted.
Technical Letters provide instructions from WADA to its accredited laboratories on how to analyse, interpret and report certain findings. Once approved by the Agency’s Executive Committee, they become an integral part of the International Standard for Laboratories (ISL) and supersede previous instructions on the same subject.
Contaminated meat, eggs or medications
The first of the new rules will bring procedures related to possible contamination together in a single document. It covers substances including clenbuterol, ractopamine, zeranol, zilpaterol, certain diuretics and clomifene.
The aim is to establish a common framework enabling laboratories to assess whether the presence of a substance could be related, for example, to the consumption of contaminated meat, contaminated pharmaceutical products or even poultry meat and eggs. Until now, these situations have been covered by four different Technical Letters.
WADA is also introducing an optional specific assessment for clomifene and has expressly requested feedback on its Minimum Reporting Level (MRL). This threshold could still be lowered as the Agency continues to review available data and scientific literature.
When the substance forms within the sample itself
The second change addresses a situation that can be even more difficult to explain to an athlete: certain compounds with steroid structures can form within the urine itself through microbial or chemical transformations of steroids naturally produced by the body.
WADA will consolidate six Technical Letters related to this issue and establish a common procedure for substances linked, among other categories, to Anabolic Androgenic Steroids and Aromatase Inhibitors.
The intention is for laboratories to use harmonised criteria to assess specific metabolites and signs of sample degradation before interpreting the result. More specialised procedures designed to determine the origin of a substance when doubts exist will also be standardised.
When a permitted medication can look like something else
The third section aims to address another problem in doping control: situations in which a Prohibited Substance appears to have been detected, but the signal may actually originate from a permitted medication, a related metabolite, an impurity, a degradation product or an analytical interference.
WADA will consolidate twelve Technical Letters that until now have individually addressed cases involving different substances. They all follow the same principle: to provide laboratories with additional tools before concluding that what appears in an analysis actually corresponds to the Prohibited Substance that seems to have been detected.
The new rule will also incorporate situations that were not previously covered. One concerns findings of 18-methyl-19-nortestosterone in the presence of levonorgestrel or tetrahydronorgestrel, which are non-prohibited substances. Another is particularly striking: laboratories will be required to assess possible clusters of 1,3-dimethylbutylamine (1,3-DMBA) findings that could be linked to sporting activities performed on artificial-turf fields with rubber infill.
From 25 Technical Letters to four
The reorganisation will significantly reduce the number of separate documents. Of the 25 Technical Letters currently in force, 22 will be consolidated into these three new documents.
Of the remaining three, WADA will retain TL27, which deals with urine sample tampering or attempted tampering. The other two, concerning tretoquinol and tramadol, will be withdrawn because their relevant content has already been incorporated into the Technical Document establishing Minimum Reporting Levels for doping control.
WADA periodically reviews these instructions as scientific knowledge and the techniques used to detect substances advance. The International Standard for Laboratories itself allows Technical Letters to be revised or withdrawn in order to adapt procedures to scientific and technological developments.
The consultation on the three new rules will remain open until 14 September 2026 through WADAConnect. The approval process will follow. For laboratories, the result will be fewer separate documents to work with; for athletes, the objective is more significant: to establish more consistent criteria for distinguishing a genuine positive doping test from situations in which a Prohibited Substance may have appeared for other reasons.
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