Integrative Review on Cannabis sativa L. Origin Traceability

Marijuana, dried and ground Cannabis, is the most consumed illicit drug in the world. Many undesirable and risky effects to human health are caused by its use. As Cannabis derived drugs and products gain popularity across the world, there has been more and more reports on mislabeled cannabinoid content of Cannabis plants, concentrates and edibles, as well as the number of health issues and deaths caused by their use. In spite of that, many countries have been making their laws more flexible as to marijuana purchase, sale, possession and consumption. Therefore, the development of methodologies capable of tracing the geographical origin of the seized samples, whether for quality control or forensic purposes, is increasingly necessary. Thus, our objective was to perform an integrative review on Cannabis traceability studies to assess the research being dedicated to this issue. We have found only 20 published scientific papers, using the databases and keywords employed, and several of these papers were published over a decade ago. We conclude that the efforts to trace Cannabis are not keeping up with the rapid changes and flexibilization in the 460 Brazilian Journal of Forensic Sciences, Medical Law and Bioethics 10(3):459-472 (2021) M. F. Ramos et al. legislation of many countries regarding legalization of the medicinal and/or recreational use of Cannabis.


Introduction
Well-established traceability systems exist in many countries for a wide array of products and processes, usually aiming to verify the provenance and/or characterize products. The traceability of Cannabis and its derivatives, such as marijuana, medicines, concentrates, edibles and fiber, is a key approach that can be used for quality control or forensic purposes. This is particularly true considering that increasingly more countries have legalized the recreational and/or medicinal use of Cannabis in recent years, in spite of the fact that Cannabis use may cause harmful and undesired effects, such as modifications in the brain morphology 1 , paranoia 2 , ischaemic strokes 3 , and death resulting from the association between psychiatric disturbances and Cannabis use 4 , for instance.
Alarmingly, the legal Cannabis market in the state of Washington, USA, is currently dominated by high-tetrahydrocannabinol (THC) Cannabis flower 5 .
Furthermore, in a study where 84 cannabidiol (CBD) products from different companies were tested, 42.85% of the products were underlabeled with respect to CBD, 26.19% were overlabeled and 30.95% were accurately labeled; other cannabinoids were also present but unlabeled, such as THC, that was detected in 21.43% of the products up to 6.43 mg/mL, cannabidiolic acid (up to 55.73 mg/mL) in 15.48% of the samples, and cannabigerol (up to 4.67 mg/mL) in 2.38% 6 .
Over the years, legal and illegal Cannabis growers have been adding all sort of chemicals to their crops, from harmless products to plant growth regulators, pesticides and some fertilizers and supplements containing unlisted dangerous substances. According to a study where individual pesticides in Cannabis were quantified, the mean levels for most pesticides were between 1,000 and 5,000 ppb; also, 12% of the samples exceeded 10,000 ppb 7 .
Pesticide contents in cannabinoid concentrates, extraction products that are very popular in the Cannabis market, were approximately 10 times higher than those found in the plant's flowers. The data used for determining the limits for M. F. Ramos et al. residual tolerance levels of pesticides on crops are based on oral ingestion exposure, although inhalation exposure through smoking can generate many kinds of pyrolysis compounds, even toxic ones, which are commonly present in the body in much higher concentrations than the orally ingested chemicals 7 .
It is clear that quantitative and qualitative analyses are of great importance for quality, provenance and authenticity verification of Cannabis products (including Cannabis-based medicines) and consequently for human safety, since the increasing expansion of the trade and use of counterfeit medicines offers serious risks to public health worldwide 8 . Additionally, data resulting from these analyses can also be used for forensic purposes to identify and trace the geographical origin of Cannabis plants and derived drugs and products. Molecular markers, such as short tandem repeat markers, have been mostly used to recognize the presence of Cannabis in materials 9 .
Taking all the aforementioned factors and the importance of Cannabis traceability into account, a research on the literature about means to achieve Cannabis sourcing was made.

Methods
The literature database consulted were SciELO, Scholar Google, ScienceDirect, and the following keywords were employed: 'geographic origin cannabis', 'sourcing cannabis', 'fingerprinting cannabis', 'fingerprint cannabis', and 'origin cannabis drug'. This last keyword obtained a result that pointed to a new approach for tracking Cannabis: the entomology. Therefore, a new keyword ('origin entomology cannabis') was added in the research.
In this kind of review it is common to establish some criteria (e.g. year of publication, number of samples, country/region of samples) when choosing the papers to be analyzed, in order to form a homogeneous set of information and making comparisons more feasible. Many articles found in the databases using the aforementioned keywords were studies about Cannabis but not about its traceability, which falls off our objective with the present review, and therefore, these articles were not considered. Since the number of Cannabis traceability papers found in the results is quite small and having many criteria such as number of samples or year of publication, would not make the information more uniform in this case and would unnecessarily reduce greatly the number of results, therefore, the only criterion employed was that the paper must have analyzed Cannabis samples to trace their geographical origin. It is important to highlight that we only considered to further analysis the results from the researches performed using the aforementioned databases, no articles were added; also, other researches on the traceability of Cannabis may exist in addition to the ones showed in the present review, but the keywords employed were not able to find them. The information collected were (1) the paper identification: authors' names, year of publication and journal, (2) which technique was employed and its type, and (3) the study scope.

Results
The three categories of information collected are summarized in Table 1.   Table 1).
The studies altogether comprehend countries from all continents, although for most countries only one study was performed, which is not sufficient to represent the entire continent. Cannabis or marijuana samples from the United States of America and from Jamaica were the most analyzed ones, followed by  (Table 1).
A comparison between the approaches above shows that genetic analyses are capable of discriminating outdoor and indoor cultivation and might even have a 100% correct classification as for the geographical origin of Finally, the entomological techniques provide unique data that are useful to complement the profile of samples and are helpful to contrast environments with very different fauna; although, since entomology is a very specialized science, its techniques are not suitable to be used in a laboratory routine for they are time consuming and require a team of trained professionals.
Different approaches used to trace the geographical origin of other materials rather than Cannabis, therefore not discussed in the present review, should be investigated and their applicability to source Cannabis should be tested.   41,42,43,44 . This points us to the conclusion that there has been progressively less scientific effort to trace the geographical origin of Cannabis, whether for forensic or quality purposes, over the last decades. Considering that, in general, the potency of Cannabis has been increasing over time in many countries 45,46 , which may lead to public health problems, this lack of traceability systems development is an alarming issue.

Conclusion
Considering that several countries have been legalizing the medicinal and/or recreational use of Cannabis and Cannabis-based medicines and other products such as edibles and concentrates in the past few years, and that are many cases of mislabeled Cannabis products 6 and even death caused by their consumption 4 , the number of papers published about Cannabis traceability is alarmingly small. The traceability of Cannabis, whether related to quality control or forensics, ought to be taken seriously.