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Establishing a window of detection when testing for drugs in young children is a very complicated task. Hair from children is finer and more porous in comparison with adult (the risk of contamination from sweat and environmental smoke is higher than in adults). The final interpretation of cannabinoid findings in the children's hair is very complicated as this can result from in utero exposure (although none of the mother admitted cannabis use during pregnancy), oral cannabis administration by the parents to achieve sedation, close contact to cannabis consumers (hands, bedding, dishes) and inhalation of side-stream smoke. Over-interpreting cannabis findings in hair can have very serious legal implication in child protection cases. Practicing scientists have the responsibility to inform the child protection authorities, courts, etc. about these limitations.

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Coca tea is a popular drink in some countries of South America where it is reputed to have medicinal properties. This preparation is composed of natural cocaine (COC) alkaloids and therefore can be banned in some countries. During an anti-doping control in Peru, the urine of an athlete was tested positive for benzoylecgonine (BZE), ecgonine methyl ester (EME) and COC (400, 180 and 0.5 ng/mL, respectively). The athlete indicated that she had consumed coca tea in the morning before the competition. As her lawyer contacted us to assess the scientific aspects of the possible involvement of coca tea to explain the adverse analytical finding, a study was implemented with similar tea bags. Five volunteers from the laboratory consumed 250 mL of coca tea containing approximately 3.8 mg of COC. Eleven urine specimens were collected for each subject for 3 days to follow the elimination of COC and metabolites (BZE and EME). All samples were analyzed by UHPLC-MS/MS (Ultra High Performance Liquid Chromatography - tandem mass spectrometer) after alkaline extraction. Maximum detection times for COC was 20 h, with concentrations ranging from 6 to 91 ng/mL. Maximum detection times for BZE and EME were 70 h and 60 h, respectively, with concentrations ranging from 6 to 3,730 ng/mL and from 6 to 1,738 ng/mL. The concentration profiles were identical for the five volunteers. This study supports the athlete’s claims. In addition, the sample of hair strands of the five subjects was collected a month later and all the hair tests showed a negative result for COC with a limit of decision of 10 pg/mg. Although it is accepted that a 4-mg dose of COC has no significant pharmacological effect, the consummation of coca tea can lead to significant legal consequences since the measured urine concentrations sometimes cannot be considered incidental. Therefore, discrimination between coca tea consummation and recreational COC abuse relies primarily on hair analysis.

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