Professor Pascal Kintz is a world-renowned expert in toxicology, most notably due to his practice of hair analysis. He is a judicial expert at the Court of Appeal of Colmar (Cour d’appel de Colmar), France, and an expert for control analyses approved by the French anti-doping agency, Agence française de lutte contre le dopage or AFLD.
Interview by Benoît Blanquart, from our partner platform esanum.fr
You can access the original interview in French here.
Prof. Pascal Kintz runs the private firm X-Pertise Consulting, which carries out expert assessments in the judicial (such as the Alègre and Fourniret cases), "historical" (like the poisoning of Napoleon), political (the poisoning of Ukrainian President Viktor Yushchenko) and sporting (doping) fields. He recently suggested that trimetazidine (Vastarel®) be removed from the World Anti-Doping Agency's (WADA) list of banned drugs, a key element in the case of French wrestler Zelimkhan Khadjiev.
esanum: Professor Kintz, why is hair analysis booming among athletes?
Prof. Kintz: Hair analysis is a technique frequently used in toxicology to detect drugs, pharmaceuticals or environmental contaminants. In forensic medicine, this technique has been recognised since 1995. It was originally used in cases of murder or rape under the influence of subtances. Now, some countries will only return a suspended driver's licence if the results of a hair analysis are presented to prove that the driver has not recently used cannabis or cocaine.
In my laboratory, we apply this forensic technique in several areas, including doping. Athletes who test positive use it to support their defence. They come mainly from Anglo-Saxon countries, where the legal system is based on adversarial proceedings. The burden of proof is on the accused to show that they are innocent.
If the athlete proves that he or she was accidentally contaminated by a product, and if they can prove its origin, then the anti-doping authorities pronounce a "no fault" and there is no sanction. A hair analysis costs only two to three thousand euros, a small amount compared to a lawyer's fees. To defend cyclist Christopher Froome [who was cleared by the World Anti-Doping Agency after testing positive for salbutamol in 2017], his team and sponsors paid 7.5 million euros in the legal case. This is unthinkable for lesser known or independent athletes.
The first time I used this technique at the request of a sportsman was in 1997. The Olympic judoka champion Djamel Bouras tested positive for nandrolone, an anabolic steroid. There was a scientific controversy about the fact that he could produce it naturally. For my part, I did not find any nandrolone in his hair. The initial sanction - a two-year suspension - was reduced to fifteen months. But it is since the Gasquet case in 2009, that the technique of hair analysis is really recognised by the international Court of Arbitration for Sport (CAS, also known as the Tribunal Arbitral du Sport or TAS].
Since then, demand has boomed. I now carry out around ten analyses of this type every month. Very few laboratories in the world are capable of doing them, and even fewer know how to detect the presence of SARMs [Selective Androgen Receptor Modulators are anabolic agents, such as ligandrol or ostarine]. But it is mainly these substances that are looked for.
We can also detect diuretics used to mask the intake of a doping product. They favour the urinary elimination of this product, often an anabolic, or increase blood retention, which lowers the urinary concentration. Some hormones, erythropoietin (EPO) or growth factors are undetectable in the hair. These molecules are too large to pass from the capillaries to the follicles. If diuretics are detected, this may indicate an attempt to mask them. If not, it is an exculpatory element for the athlete.
esanum: When is this test relevant?
Prof. Kintz: Hair analysis is valuable when urine analysis shows almost nothing - either because the amount of substance in the body is small or because it has been consumed for a long time - but especially when the concentration measured is uninterpretable. In these borderline cases, hair analysis can help. Each centimetre of hair represents what has circulated in the body during the corresponding month: if the substance is clearly found in it, this indicates chronic and long-standing consumption, and therefore reinforces the hypothesis of doping. If there is nothing in the hair, then accidental contamination is supported.
How can an athlete unintentionally have a doping substance in the body? Two scenarios are possible. Firstly, they could have ingested the product without their knowledge. Doping substances have already been found in meat or toothpaste. The same applies to certain diuretics which are prohibited by the anti-doping authorities because they "mask" the use of doping products. Traces of these diuretics can be found in medicines that are authorised. Second scenario: the athlete has unintentionally been impregnated with a prohibited product, either through contact with a person who regularly consumed it - this is known as "cross-contamination" - or because he or she has been exposed to "environmental" contamination.
Several cross-contaminated athletes have been cleared by hair analysis. Examples include world pole vault champion Shawnacy Barber, who was able to compete in extremis in the 2016 Olympics after being suspected of doping with cocaine, and Laurence Vincent-Lapointe, 11-time world canoe champion, whose urine analysis revealed the presence of ligandrol, an SARM.
Very recently, three female athletes with abnormal urine results were given a "no fault". They had a very low concentration of the substance or its metabolites in their urine and a negative hair analysis. They were also able to prove that their partners had consumed the substance, which we confirmed by analysing their hair. In all these cases, hair analysis supported the hypothesis of cross-contamination.
esanum: What is a "sex defense"?
Prof. Kintz: Typically, cross-contamination occurs during intimate exchanges. Anglo-Saxon lawyers have therefore named this line of defence "the kissing defence" or "sex defence". The Gasquet case is emblematic in this respect. In 2009, the French tennis player tested positive for benzoylecgonine, the main metabolite of cocaine. He denied any intentional ingestion. However, he had repeatedly kissed a female cocaine user a few hours before the test.
We analysed eight segments of his hair, each measuring 0.5 cm, from the root to the tip. No cocaine was found in any of the segments, which meant that the person was not a regular user. This negative result did not invalidate the urinalysis result, but simply indicated a very low exposure to cocaine.
In two previous studies I had shown that a 15mg dose of cocaine can be detected in the hair, but not a 4mg dose. The athlete had therefore consumed or been in contact with a very low dose, less than 15mg, with no effect on performance. Furthermore, according to the urine analysis, the cocaine consumption dated back to approximately twelve hours before the test, and corresponded rather to a dose of 2-3mg. This quantity is very low, as a typical "line" is of the order of 50 to 100mg of cocaine. The hypothesis of accidental contamination was retained by the judges and Gasquet received a minimal sanction.
esanum: What is "environmental" contamination?
Prof. Kintz: Cross-contamination requires contact between the athlete and a third party. But contamination can also occur through passive exposure to the product. In a recent case, it was another tennis player who was "saved" by hair analysis.
Luciano Tacchi, 18, also tested positive for cocaine. We analysed a strand of his hair four months after the urine test. Each segment contained low concentrations of cocaine, with a linear increase from the root to the tip. This pattern was considered highly indicative of external contamination, with older hair being more concentrated due to longer contact with a contaminated area.
Studies have already shown that cocaine can be found in the hair of spouses and children living with cocaine users, sometimes at levels higher than those found in the hair of users. Nails from Luciano Tacchi's toes were also tested. The result was negative. However, the analysis of a washing solution from these nails was positive, indicating a possible "environmental" contamination.
In order to confirm this, the player's lawyer requested a hair test of the player's aunt, with whom he had stayed and who was also a regular cocaine user. The aunt's hair showed identical levels of concentration to those of the athlete. The International Tennis Federation accepted this explanation and the player was given a "no fault".
esanum: Are there any limitations in the application of hair analysis?
Prof. Kintz: To perform a hair analysis, the athlete must have hair. This is not always the case. Hairs can also be analysed, but due to their irregular growth it is not possible to perform segmental analysis. Furthermore, the detection window differs from that of hair, and each anatomical location has its own specificities. As a last resort, we analyse the nails. Here too, the rate of substance fixation varies between hands and feet.
The colour of the hair is an important element. The incorporation rate in blond hair is lower than in dark hair, the ratio being one to five. We have to take this into account. Another factor to consider is cosmetic treatments. They 'open up' the hair scales, accentuating the damage caused by UV, water and pollution on the cuticle. The chemicals used for these treatments - bleaches, dyes, etc. - are usually strong bases: they reduce the hair's thickness and make it more flexible. - The chemicals used for these treatments - bleaches, dyes, etc. - are usually strong bases: they reduce the concentration of the desired substances by up to 50%. Even shampoos such as Ultra Clean® can reduce this concentration. If an athlete dyes his or her hair, which is common, we must resort to body hair or nail analysis.
The major limitations of hair analysis are related to the doping substances themselves. The lack of hormone detection, for example. As for anabolic agents - steroids, glucocorticoids and SARMs - they are poorly incorporated into the hair. According to the World Anti-Doping Agency, these are the most commonly used substances [in 2017, they accounted for 44% of doping cases1]. However, athletes often use them on a long-term basis. We therefore do not look for the most important metabolite, but for those with the longest detection window after administration.
Finally, while some products are permanently banned - notably anabolics - others such as cannabis or cocaine are only banned during the competition. However, the rate of hair growth is not sufficiently reliable to be able to state that the product was consumed at the time of the competition.
esanum: Can hair analysis become a doping control technique?
Prof. Kintz: The World Anti-Doping Agency and the International Olympic Committee are, for the time being, totally opposed to it. Their position is rather dogmatic: only urine and blood tests are authentic. This could change. Firstly, because the legal bodies of the sports federations and the CAS now recognise the validity of capillary analysis, used to document the consumption profile retrospectively. Secondly, because this technique could allow a more refined approach to the fight against doping, when combined with other laboratory results, anamnesis and pharmacological data.
1. WADA estimated in 2016 that the prevalence of doping among athletes, worldwide, was between 10 and 30%. In 2014, the frequency of positive tests was only 1.4% (1.2% for France according to the AFLD).