The analysis of drugs in hair is generally associated with contemporary forensic applications, to detect whether a suspected drug user has been taking banned substances and, if possible, to track the time course of usage by following the distribution along the hair. It has also been used to determine whether animals raised for meat have been given illegal hormone growth promoters. However, before these applications were developed, hair analysis was also used in an anthropological context.
In the early 1990s, the hair of South American mummies dating from 1000 BC to 1500 AD was analysed by radioimmunoassay to reveal the presence of cocaine and its metabolites benzoylecgonine and ecgonine methyl ester. These findings, later corroborated by GC/MS, were taken as evidence of coca leaf chewing by the indigenous people and helped to suggest that this practice originated in the Andes.
Another study published about the same time reported the detection of cocaine, nicotine and tetrahydrocannabinol in mummies from Egypt (1000 BC to 400 AD). This report stirred up a hornet's nest. Cocaine and nicotine are derived from South American plants and there were no known trans-oceanic voyages to Europe before Columbus sailed to the Americas. So, some commentators have criticised the work, citing the speculative nature of the requisite voyages, poor experimental techniques and external contamination.
In Germany recently, this work was expanded. A collection of 70 human and animal mummies was assembled as part of an ongoing mummy project involving specialists from anthropology, pathology, radiology, molecular biology and toxicology. One of the many operations carried out was to gather evidence of the use of drugs and this was accomplished by analysing the hair of pre-Columbian mummies for drugs.
Only eight of the human mummies had sufficient hair for sampling. The analyses were carried out by Frank Musshoff and Burkhard Madea from the Institute of Forensic Medicine, Bonn, and Wilfried Rosendahl from the museum in question, the Reiss-Engelhorn-Museum in Mannheim. In the first instance, the samples were analysed by an established GC/MS procedure for opiates, cannabinoids, cocaine and similar substances.
A second set of samples was washed successively with water, petroleum benzine and dichloromethane and the washes retained. The cleaned hair was cut into pieces and ultrasonically extracted with methanol. The washings and the extract were each screened by GC/MS using a mass spectrometric library. They were also subjected to targeted analysis for nicotine and its metabolite cotinine in selected ion monitoring mode, using deuterium-labelled internal standards to allow quantitation.
The target analyses for drugs in general were all negative but three of the mummies tested positive for nicotine: an adult woman from Peru or Argentina radiocarbon dated to 1095 ± 50 AD; a child from the Peruvian Chancay culture dated to 1415 ± 16 AD; a female bony skull complete with scalp and well-preserved braided hair from Peru that had not been dated. The nicotine levels were 57.5, 14.1 and 11.4 ng/mg, respectively, but cotinine was absent in all cases. The method quantitation limits were 0.12 and 0.10 ng/mg for nicotine and cotinine, respectively.
The nicotine concentrations are of the same order as those reported in the hair of modern-day smokers but the absence of its primary metabolite is puzzling. Given the nicotine concentrations present, the team expected to find cotinine at levels well above the quantitation limit. Although cotinine is not always detected in every active smoker, to detect none in all three mummies may be considered too coincidental.
One explanation offered by the researchers is contamination of the mummies by smoking visitors or museum employees during their collection, storage and display. However, neither nicotine nor cotinine were detected in any of the washings, which would be expected for external contamination. It is possible that the hair had been cleaned during mummy storage but this could not be confirmed because the earlier records are incomplete.
In addition, the team were able to exclude modern contamination as the mummies had been stored in their vitrines for 100 years before being rediscovered and examined in 2006.
Another potential solution is the use of the tobacco plant during a sacred ritual in which the shaman would treat an ill native with tobacco smoke but this is merely speculative.
The team concluded that the active consumption of tobacco during the lifetime of the subjects, while implicated, could not be proven. Future work will include an examination of the soft tissues of the mummies which might provide more evidence for tobacco use.
by Steve Down
May 15, 2009
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