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Unternavigation im Bereich: The Procedure

Saliva

abuse. And not only that: in contrast to urine, saliva can also provide information regarding the level of current intoxication, which would be of great significance for traffic checks. No one has to urinate into a cup or expose their genitals.

However, there is a whole series of problems and unanswered questions with regard to saliva, which must be taken into consideration:

  • It must be assumed that the saliva is subject to severe fluctuations from one subject to another. The saliva secretion is a complex process, whereby anatomical/histological conditions play an important role. Even factors such as stress, hunger or underlying systemic diseases may have an influence on the composition and consistency of saliva. As a result, standardisation of the method is practically impossible.
  • Different substances reach the oral fluids through different methods and forms. For example, cannabinoids can be detected only for 30 minutes after initial use. Cocaine and its metabolites can be detected for longer duration, but their detection time is severely influenced by chewing gum or lemon candies (Halwachs 2011). The latter aspect questions the theory that saliva cannot be manipulated. Further research findings are still pending.
  • The volume of saliva collected during sampling is very less. Therefore, salivation is simulated – often by the saliva collection systems by using acidic media. This influences the pH value of the sample and thus influences the substances searched and their detection times. In addition, stabilisers are used for transporting the sample. Even these can influence the analysis, however further research is required in this regard.
  • The simulation of salivation in itself represents bodily intervention and as a result use of this method is not permitted, for example, in penal system. You can find more information in this regard under in penal system / probation services..
  • The low sample volume requires highly sensitive and expensive analytical methods. There are quick tests available in the market. But major international studies such as ROSITA oder DRUIDdo not recommend these tests due to high probability of errors and lack of standards with regard to threshold values.

It can be summarised that the saliva as a medium has a huge potential, but it has not been researched adequately to use it in clinical practice. You can find more information about this topic in our Download Centre.

Capillary blood

Any mixture of tissue fluid and blood is defined as capillary blood, which is collected by piercing fingertips or ear lobes.
Blood as a medium has been researched adequately. However, capillary blood is not pure blood, which results in certain problems:

  • Differences in the analysis of capillary blood and venous serum or whole blood are well documented. Thus, blood sugar measurement from capillary blood is no longer permitted for diagnostics, therapy and post-operative care of gestational diabetes since 2011. Even deviations in the blood gas analysis were established in many studies. Therefore, capillary blood is not recommended.
  • Capillary blood contains a natural trace of tissue fluids. In order to minimise this, the first few drops should be rejected. However, it is hardly possible to quantify the proportion of tissue fluids.
  • This problem is exacerbated by the stimulation of insertion point. This can be done only with suitable hyperemising ointment or heating, because mechanical simulation like massage or pressing will further change the composition of the collected sample.
  • In addition, there is the risk of contamination, because taking samples with capillary tube is not a closed system. The research regarding possible contamination – e.g. due to hyperemising ointments – and its influence on tested substances is surprisingly sparse.
  • The extremely low quantity of sample drastically limits the reproducibility of the analysis. As a result, it significantly increases the probability of errors.
  • It should be noted that even this method of collecting capillary blood represents bodily intervention. Thus, the same legal consequences for saliva are applicable here as well.

It can be summarised that the capillary blood as an alternative for urine in clinical practice has not been researched sufficiently. Various medical fields show that ointments, for example, may have an influence on the analysis. Whether and to what extent it can influence the substance abuse requires more research. However, capillary blood is not above suspicion of providing protection against manipulation attempts.

Uncertainties regarding the above questions appear to be substantiated in scientific research:
Böttcher, Rönitz and Dahmen submitted the results of a study in 2014, whereby the objective of the study was to check whole blood as an alternative medium for EtG determination. They reached the conclusion that whole blood represents a possible alternative to urine for EtG evidence and thus “can be collected in future even as capillary blood”.