Cannabis as an illicit crop: recent developments in cultivation and product quality
A changing technology
Product quality: increasing potency
Some control implications
Author: K. SZENDREI
Creation Date: 1999/12/01
Professor Emeritus, Department of Pharmacognosy, Szent Gyorgyi Medical University
The unusually high biological plasticity of Cannabis sativa is manifested in its seemingly endless varieties of both the fibre and the drug type. This capability, together with an aggressive propagation capacity, has made cannabis the most universally available raw material, growing or cultivated, in every continent of the world. The same capability of biological plasticity and diversity makes the plant a perfect target for all manner of human experimentation. Recent breeding efforts have yielded fibre hemp varieties for large-scale agricultural production with ever lower and stable levels of tetrahydrocannabinol (THC), thus opening up new market opportunities for hemp as a raw material for industry. At the same time, clandestine horticultural experimentation, using new technologies and widely accessible information, has led to the development of new cannabis types with extremely high THC concentrations in the flowering top. The latest fruit of such clandestine research is the rapidly proliferating indoor cannabis cultivation to be found in North America and Europe. This "high-tech" clandestine industry appears to have had a radical impact on the American and European illicit cannabis market and may in the future increasingly displace traditional products by offering higher reliability and potency at lower risk. It exploits hesitant or lenient drug control policy and divergent attitudes among Governments and the public at large in the major consumer areas.
The present paper reviews some of the typical characteristics of the above development and assesses actual and potential implications.
Human interest in cannabis as a natural source of pleasure and as a raw material has evolved under the ever-present influence of changing economic, social and political interests during the plant's unusually long cultural history. The result today is a truly global illicit market for the principal cannabis products of marijuana and hashish, and a new market seems now to be emerging for fibre hemp as an industrial raw material [1-4].
While the driving force behind the unprecedented global expansion and evolution of cannabis has without doubt been in human use throughout history, its unique biological and chemical characteristics have been fundamental to this continued progression and metamorphosis. Thanks to its unusual biochemical plasticity, it has been an eminent target for domestication and highly amenable to changing cultivation practices; its high adaptability and aggressive propagation capability have helped it to invade most climatic zones and continents; and the uniqueness of its chemical ingredients have made Cannabis sativa, throughout history, one of the most popular raw materials for an array of applications, both recreational and medicinal. Many of the ancient applications have vanished, while others persist and are now evolving in ways never seen before.
The most spectacular expansion and qualitative change has been in the plant's production and application as a drug of abuse. Cannabis has always been used for recreational purposes in a variety of forms and qualities in various parts of the world. Most recent developments seem to be characterized chiefly by two new phenomena: a gradual translocation of cultivation for drug production to technologically advanced countries and the transformation of cultivation and production practices under the influence of rapid advancements in the application of new technology and information. As a result, a new supply market, partly grafted onto the existing traditional markets, and new products of greater potency and more reliable quality are emerging.
The new cannabis supply is gradually moving closer to the principal consumer markets and is offering superior drug quality at lower overall risks, competing with the traditional products and suppliers. While the phenomenon is still confined to a small number of countries in the industrialized world, it is rapidly spreading and thus demanding particular attention on the part of the Governments concerned.
While cannabis in its various forms is the most widespread illicit drug on all continents, the various issues related to its control are the focus of debate and varying interpretation by the public and by Governments alike. The continuing divergence in approaches to control is doubtless a further factor contributing to its expansion as a drug of abuse as well as to the recent transformation of the cannabis supply market [3, 5].
The present paper reviews certain scientific and technical aspects of the new global developments in illicit cannabis cultivation and drug production. It brings together data from a variety of sources, but predominantly publications of a scientific nature. It is thus an effort to rectify the long-prevailing imbalances in national and intergovernmental reports and reviews, which tend to rely exclusively, or primarily, on information and data derived solely from enforcement and government sources, accompanied by scant technical interpretation.
In this review of recent global, regional and specific national developments, certain technical aspects of illicit cannabis production emerge which appear to distinguish it from that of other significant natural drugs of abuse, one such aspect being the crucial impact of new technologies and information. Such analysis inevitably suggests a rather alarming future scenario, namely a major qualitative change in illicit cannabis production, distribution and consumption.
With the expansion of the new technology for illicit cannabis production, the inadequacies of current control approaches are becoming increasingly apparent. Redefinition and adjustment are therefore called for in a control system which has essentially remained unchanged, both conceptually and in practical terms, since the middle of this century. Some suggestions for policy and regulatory responses are prompted by analysis of the complex impact of recent developments.
Supply variety and variability
In contrast to all other plant-based narcotic drugs, illicit cannabis products originate today from at least three qualitatively distinct sources:
(a) Outdoor illicit cultivation, either simple/traditional or more sophisticated (e.g. sinsemilla production);
(b) Collections in naturalized cannabis populations which have escaped from previous licit or illicit cultivation ("ditchweed", "wild hemp"); and
(c) Plants produced indoors by means of sophisticated growing technology.
While (a) has been the exclusive source for centuries, (b) has recently become a source of herbal cannabis in a few countries, and (c) is the most recent product of technological advances in this field, rapidly "conquering" an increasing number of countries.
Each of these areas has undergone substantial change and expansion during the last decades so that a rather complex production pattern now seems to be emerging with considerable regional and national variations. Production has reached significant dimensions in specific countries or groups of countries. Also, new products with far more diversified potency are acquiring increasing importance on the illicit markets. The influence of all those individual developments has to be assessed, therefore, when monitoring and evaluating global cannabis supply and consumption. Yet most reviews confine themselves either to classic cultivation and drug production, and to the two traditional products, marijuana and hashish, often confusing those distinct areas. As will be seen below, there are many reasons for this seeming lack of clarity, one of them being, without any doubt, the lower priority assigned by many countries to cannabis compared with opium poppy-opium-heroin and coca-cocaine.
The "wild cannabis" issue
References to the existence of "wild cannabis" or cannabis growing wild as part of the natural vegetation are frequent in both governmental reports and the scientific literature. The source countries of such references are typically in North America, Europe and the Commonwealth of Independent States (CIS), less often in Africa, with confusion frequently resulting in both enforcement and government circles. Such plant populations are occasionally identified as a significant problem for enforcement, being the main or sole source of locally produced marijuana. Both the plants and the products are often reported as cultivated cannabis, usually without any further specification of the origin or quality of the material. Such reports may, in turn, obscure real cannabis cultivation trends and hinder analysis of trafficking and consumption patterns. What is worse, the products collected from such sources are sometimes qualified as "unusually potent" or "high-quality", but with no proof, or only anecdotal evidence, for such suggestions (e.g. the marijuana collected in the Chu Valley of Kazakhstan). As a result, the discovery of "wild cannabis" populations in some countries not only poses a dilemma for legislation and enforcement but may also obscure national and international drug control priority setting. A recent analysis  of the "wild cannabis" situation in the Republic of Kazakhstan provides a good example of this scenario. Thus, the need for technical clarification is evident.
First, "wild" cannabis populations do indeed exist in practically all countries where the plant was previously cultivated either for drug production or as a source of fibre (see figure I). Such populations are the result of the plant's aggressive reproductive and survival capability. It is of significance that, unlike most domesticated plant species, which have existed for centuries exclusively in human cultivation and are no longer capable of competing and surviving in the natural environment, cannabis always escapes from cultivation and survives successfully in most natural environments. Such plants become naturalized constituents of their floral environment and need no further human protection for their survival. However, in strict botanical terms, it would be more correct to identify such vegetation as "naturalized" or "escaped" rather than "wild" cannabis. Systematic cultivation trials with cannabis seeds collected from the various climatic regions of the world have convincingly documented the extraordinary adaptation capability of the plant [7, 8]. Descendent plants grown from seeds originating in tropical regions from drug-producing plants were not only able to survive but also to produce good-quality drug and viable seeds in a variety of climatic zones, except for extreme conditions [9, 10].
More important from the drug control point of view is the fact that naturalized cannabis populations are usually found in areas close to previous cultivations, but may sometimes gradually expand or disperse to adjacent areas. The overall size and cannabis density of the individual "pockets" in any given area and the potency of the collected drug material (typically herbal cannabis) are in all cases a function of the following main factors:
(a) The type and potency of the ancestor plants;
(b) The nature, extent and duration of the original cultivations (licit fibre hemp cultivation or illicit drug production) and of the subsequent discontinuation (partial or complete abandonment, forced eradication, with or without follow-up); and
(c) The quality of the natural or agricultural environment (soil, climatic conditions, competing vegetation), the use and intensity of weed control and the extent of human activities (e.g. animal husbandry, grazing, etc.).
While the influence of the latter two factors has not been studied in any great depth, the influence of ancestor-type cannabis on the quality of escaped vegetation ("wild cannabis") has been repeatedly studied in various contexts. The intensive research organized and coordinated by the United Nations in the 1970s deserves special mention. The results of the early studies up to 1980 have been extensively reviewed by Baker and others . The following conclusions with practical implications can be drawn:
(a) The descendent plants in "wild cannabis" vegetation essentially retain the morphological and chemical characteristics of the ancestors, e.g. drug-type plants yield naturalized descendants with relatively high THC levels, while fibre hemp ancestors usually result in descendent plants with low THC content (figure I);
(b) Considerable variations in THC content have been seen among individual populations in all these populations. This is no more than the logical result of the great variability of the ancestor plants and is demonstrated clearly by the "wild cannabis" populations found in many European countries, originating almost exclusively from previous industrial hemp production. The vast majority of the individual plants in such vegetation contain low-to-moderate levels of THC (see figure I). At the same time, notable exceptions have been seen in almost every country, with individual plants containing as much as 1-2 per cent THC in the flowering top [12-17];
(c) Significant factors which may explain some of the unusual variations and the high-THC exceptions are the following:
(i) Many of the older fibre hemp varieties were in actual fact rather rich in THC, since psychoactivity was not used as a selection/breeding criterion prior to the 1970s. Since this new criterion in selecting new industrial varieties has been generally applied, the accepted and guaranteed THC levels have gradually been reduced (figure II). This new trend is still continuing with new fibre hemp strains containing virtually no THC (for more detail see ). Clearly, individual plants escaped from such cultivations must be very low in THC.
(ii) Once cannabis consumption started to rise in the United States of America and Europe, interest in locally available "wild cannabis" and in local illicit breeding and cultivation using seeds from marijuana- or hashish-producing countries started to emerge (see next section).
Logically, most descendent "wild cannabis" plants of high-THC ancestors carry relatively high THC levels [12, 13, 17-24], and such plants not only continue to propagate but also occasionally cross-breed with low-THC individuals. In addition, they serve as starting material for further clandestine breeding experiments. Such clandestine experimentation developed first in the United States and subsequently in a number of European countries. In these cases, naturalized cannabis is often used in cross-breeding experiments to produce more resistant strains (hybrids) which are better adapted to local growing conditions and have considerable THC-levels .
Supply moves closer to consumption: increasing illicit cannabis cultivation in technologically advanced countries
Cannabis cultivation for drug purposes has for centuries been concentrated in a few geographic areas usually distant from the main consumer countries (traditional consumption excepted) and has been a conservative industry based on long-accumulated empirical knowledge and an old and simple technology (figure III). Changes have been few and slow and have consisted mainly of geographic shifts in traditional practice, usually moving with people migrating from one country or continent to another. It is well documented, for example, that the practice of cultivating cannabis for drug production moved from China and/or India to the Americas and gradually to most countries on the African continent, with specific groups of peoples moving either as workers, explorers, traders or exiles and being familiar with both cannabis consumption and cultivation. Given the plant's enormous adaptability, there have been few, if any, geographic limits to growing cannabis on any continent, and it was only a question of time and of new demand before expansion was to take place. It was therefore to be expected that the benefits of rapid pro- gress in life sciences and agricultural technology would sooner or later have a substantial impact on this rather outdated agro-industry. This process has for obvious reasons been slow in previous decades and has consisted mainly of crop enhancement and protection practices through the application of fertilizers and chemical pesticides.
Figure III. Comparison of some typical attributes of "low-tech" and "high-tech" illicit cannabis cultivation and production
|Traditional||High - Tech|
Old, traditional types
New, highly specialized, for THC production/yield selected types
Generative/sexual (via seed)
Locations in traditional,underdeveloped areas/countries
Locations in technologicallyadvanced countries
|Size tends to be larger, dependingon suitability of land (location,quality) labour and market potential||Size is extremely variably(few plants to large surface),not function of land avail.|
|Dependent on tradition, customs, simple agricultural practices||Increasing dissociationtraditions and from agriculture|
Low technology requirements
|Information andtechnology dependent|
|No/minimal changes in cultivationproduction practices and in product||Changing (increasing) sophistication ("clandestine research")|
High (2-4 harvests p.a.)
Internal limits(plant physiology)
Marihuana, hashish, hashish oil
Predominantly for international trafficking/ distribution/consumption
More reliable (constant) quality, increasing potency
Mostly for in-country distribution/consumption
The geographic flexibility of illicit cannabis production is well reflected in at least two recent developments: in the large local marijuana production since the 1960s and 1970s in the United States [25-28] and in the rapidly expanding illicit, mostly indoor, production in some countries of Europe [24-27]. Although the former phenomenon is not new, it is significant that it has been able to resist continued enforcement pressures , annual eradications and considerable competition from abundant marijuana supplies from Latin America. In recent years, the average share of locally produced cannabis herbal products on the United States market has reached significant proportions, according to some estimates as much as 20-50 per cent, representing an approximate volume of 2,000-7,000 tons, and approximately 30 per cent is estimated to originate from local indoor cultivations in Canada [25-27]. A similar situation appears to be developing in a few countries of Europe [29-35]. The extent of local cultivations, their geographic spread in the United States and Europe and the increasing technological sophistication involved amply demonstrate the high competitiveness and economic viability of this gradually progressing illicit industry. The higher production costs are clearly offset by what is an advanced and more cost-efficient technology, and by a more reliable and potent herbal product. All these factors, together with the lower level of entrepreneurial risk involved in the entire cultivation/production and distribution chain, naturally make local cultivation more attractive than importing marijuana from the classic producer countries via international trafficking.
However, the European cannabis supply situation has been different in the past from that of the United States and continues to be different in several respects:
(a) The North American cannabis consumer market has been dominated by herbal cannabis (classic marijuana, sinsemilla), albeit with substantial differences between the United States and Canada. The European market has been and continues to be different and more diversified. The various forms and qualities of the herbal material tend to play a relatively minor role in many countries of Europe, since hashish is the principal cannabis product of choice for European drug abusers [30-32];
(b) As might be expected given the difference in geographic location of the logical supplier countries, the main source countries for herbal cannabis are quite different for the United States and for Europe. The principal suppliers to the North American market have been Mexico, Colombia, Jamaica and Thailand, plus an increasing local production; in Europe, herbal cannabis originates from a large variety of smaller suppliers [27, 29-32], and sizeable local cannabis herb production only started recently.
The most significant change taking place at present in illicit cannabis supply in both Europe and North America is the rapid proliferation of cannabis cultivation under advanced technological conditions, usually indoor. The origins of this new trend may go back as far as 10 to 15 years but it has gained considerable momentum, intensity and sophistication during the last decade. Its geographic spread within and to some extent outside Europe is clearly discernible from many reports. The situation is by far the most advanced in the Netherlands, where since 1993 an estimated minimum of 50 per cent of the local consumption is supplied by the so-called "netherweed" coming from local indoor cultivations [30, 35]. In addition, increasing quantities of the same material are being trafficked to neighbouring countries, first and foremost to the United Kingdom, and the know-how has been successfully exported to other countries in Europe such as Austria, France, Germany, Hungary, Slovenia, Switzerland, the United Kingdom, and certainly many more [29-31]. A similar trend has been apparent in the United States and Canada for nearly a decade [25, 27, 28]. There have even been reported attempts to transfer the same technology to developing countries with favourable growing conditions and less strict controls (e.g. Papua New Guinea).
A number of important factors and forces have contributed to this disturbing development, including the clever and opportunistic application of advanced agricultural and horticultural technologies in some countries, under the conditions of lenient government policies on cannabis-supply control and universally accessible information, in print and electronic form, on new growing techniques [22, 36, 46, 47]. Further aspects of indoor cannabis cultivation will be discussed later in this paper, while another paper in this issue will discuss the particular situation in the United Kingdom .
There may be many forces driving this new trend, and it is likely to have a number of effects on the cannabis supply situation (see figure III). The most obvious and visible of these would appear to be:
(a) The new technology offers several major advantages in terms of productivity and yields, the quality of the drug produced and overall financial returns. Its independence from normal agricultural conditions (suitable soil, sufficient labour force, climate) and from any seed supply (the use of vegetative propagation through cloning), together with the wide availability of material, equipment and technical information are added bonus points favouring indoor cannabis cultivation in its high-tech form;
(b) The greater proximity of the drug supply source to the consumers in the countries where these developments are now taking place further reduces the overall risk of detection and interception. This is especially important in the case of illicit cannabis products, which tend to be bulky and relatively easy to detect during inter-country or inter-continental trafficking. The effects on drug trafficking and consumption between neighbouring countries within a given region are clearly significant, and this subject probably deserves a separate discussion. It is telling that once the new cultivation practice had become established in the Netherlands, it rapidly spread across Europe, and police reports [29-31] reveal and confirm a "Dutch connection" in most cases. With few geographic, climatic and technological limitations, combined with established cannabis consumer markets in most European countries, the scope for effective control or elimination of cannabis appears to be rather limited. Further complications may arise from the revival of licit cannabis cultivation, often in the same countries (see separate paper in this issue of the Bulletin);
(c) Indoor cannabis cultivation typically takes place in countries with established or expanding marijuana and/or hashish consumption, usually supplied by international trafficking networks. The new local production is superimposed on an existing drug supply and thus increases local drug availability, which may in turn contribute to the further expansion of the consumer market. In addition, indoor cannabis cultivation is eminently suited to small-scale production, satisfying small and closed circuits of users or exclusively personal use. In this respect, it appears to have the same impact on legislation and on the implementation of national drug control laws as the expanding clandestine synthetic drug manufacture ;
(d) It is difficult to predict to what extent the new cannabis cultivation trends might in the future affect traditional cannabis cultivation practices and the global and regional market shares. If present attitudes towards cannabis abuse and its control continue to prevail in many countries affected by the problem, a new cannabis market structure may gradually emerge in countries where the traditional products with varying and usually inferior quality will gradually lose market share. This is already the case in a number of European countries and in the United States [27, 30-35, 38, 39]. In turn, technically inferior traditional cannabis cultivation and drug production may become ever less competitive on the global drug markets when confronted with an aggressive, high-output production technology;
(e) A somewhat different and more speculative scenario would consist of two qualitatively contrasting cannabis supply and demand markets gradually developing and coexisting. According to this scenario, one distinct market would develop or rather "survive" in the traditional and adjacent areas, relying on classic cannabis products, and eventually displaying signs of a slow transformation under the impact of more advanced cultivation and production practices. A separate producer-consumer system may become established in some technologically advanced countries on the basis of the new high-tech supply and supported by consumer preference for more potent and reliable material. The history of cannabis provides the best evidence that such regional differences always existed, and those differences may be further accentuated through the recent technological innovations. Clever marketing tactics and consumer preferences would undoubtedly contribute to such developments [32, 38, 40-42].
Similar scenarios have recently been postulated by some drug policy analysts for heroin, cocaine or synthetic drugs in a different context .
As mentioned before, the recent developments in the long history of cannabis appear to be driven by a renewed scientific and technological exploration of the vast inherent plasticity and diversity of the species and by the multiple economic benefits to be derived from such intense efforts. These efforts have recently gone in two opposite directions, with completely different purposes, and both directions can be regarded as logical extensions of previous similar efforts.
It may seem somewhat paradoxical, yet revealing, to compare the recent developments in cannabis cultivation and drug production technology and the resulting product qualities with those of the other important narcotic plants and corresponding narcotic drugs, opium-heroin and cocaine. Such analysis will reveal notable analogous trends and similarities, together with some specific differences.
The most significant similarity is undoubtedly an advancing technological sophistication and diversification either in cultivation or in processing, combined with more diversified products and an increasing product purity/potency. Such developments appeared first in opium poppy-opium-morphine-heroin manufacturing and were the indirect result of progress in legitimate research as well as rapidly spreading clandestine know-how. The targeted selection of high-yielding (morphine) opium poppy varieties for the legitimate opiate industry (for a review of this subject, see ) and of low-morphine varieties for floristic purposes  in the 1970s and 1980s was clearly the symbolic forerunner for the breeding of similar specialized cannabis types. Contrary to expectations, this progress quickly produced negative side-effects in the clandestine sphere in that the morphine-rich poppy straw became an increasingly attractive raw material for heroin manufacture. In the case of coca, technological progress has been far more limited in scope, mainly confined to coca leaf processing and the refining of cocaine.
However, the purpose of legitimate industrial research has been the exact opposite in the case of cannabis: the creation of fibre-producing plant types with ever lower (and ultimately 0 per cent) THC contents. At the same time, clandestine research on cannabis is heading, predictably, towards ever more potent forms of the drug and is thus producing plant types with ever higher THC contents (figures II, IV and V).
In terms of capability for geographic expansion, neither opium poppy nor coca can compete with cannabis, since their biological potential for propagation to new areas is far more limited. It is not surprising, therefore, that relatively few geographic expansions in their growing areas have been observed during the past few decades. The most significant of those taking place has been the transfer of illicit opiate production to countries in South America. No similar significant shifts have been seen in coca cultivation, although historical evidence points to the possibility of such shifts occurring.
"Progress" in cannabis production and technology in North America and Europe is evidently facilitated to a considerable degree by the quasi-universal availability of technological solutions and the wide dissemination of information [22, 36, 46, 47]. Here, the analogy with the recent developments in clandestine synthetic drug manufacture is quite striking . Yet, the specificity of the cannabis "information revolution" resides not only in the fact that recipes, growers' advice and market opportunities are exchanged on the worldwide information net, but also extends to the widely divergent governmental responses, policies, and legislation [5, 48]. Some of the typical technological features of this industry are discussed in a separate paper of this issue of the Bulletin .
The progressive application of new knowledge and technical solutions in the illicit production of cannabis has resulted, during the past two decades, in a clandestine business which has little in common, except perhaps for the plant species, with the traditional cannabis-growing industry. New varieties are being developed, new technologies applied under artificial growth conditions, and yields and product potencies multiplied. The relationship of the efficiency of this new high-tech cannabis production to that of traditional marijuana or hashish production appears much the same as that of the highly integrated and mechanized poppy straw production and processing to traditional opium production and processing .
Interestingly, since the 1970s there has been a plethora of publications, both scientific and governmental, suggesting an increase in the potency (THC content) of the various traditional cannabis products, in particular the herbal material. First, the Drug Enforcement Administration (DEA)/National Institute on Drug Abuse (NIDA) Marijuana Potency Monitoring Project Reports [25, 41, 49] suggested quite considerable increases in the potency of cannabis products available on the United States market between 1975 and 1984. Such increases were subsequently quoted and confirmed by a number of later reports [e.g. 28, 41], which were soon followed by similar studies in Europe, mainly in the United Kingdom [11, 14, 21, 50]. The increases in potency were attributed either to better plant material, continually improving agricultural practices and improved processing and packaging methods, including the production of higher-quality products such as Thai/Buddha sticks, "buds", or sinsemilla (figure IV) or, alternatively, to better enforcement and seizure procedures (e.g. representativeness, sampling and storage). It appears that the influence of new, more advanced technologies as a significant factor in the improvement of cannabis products has only been noted since the 1980s. Surprisingly, the extreme natural variability of the plant and the relatively low stability of the marketed product have been considered only marginally, and no reference has been made in those few discussions to the great advancements and continuing diversity of laboratory techniques in the assay of THC contents (It is significant in this respect that THC was not described definitively until 1964 and was only available as a synthetic reference material from the late 1960s. No accurate chemical assays of cannabis potency were possible before these dates. All previous statements must therefore be regarded as somewhat approximate, with little comparative value). Yet, both factors may considerably affect the reported end-results and hence any conclusion on the products' estimated potency [8, 16, 18, 20, 23, 50-54]. It follows that different studies have often yielded quite different results, and the assertion claiming an overall increasing trend has been subsequently challenged [51, 52], doubts being raised as to the validity of the potency increases reported. The analysts in question suggested that considerable product diversity already existed previously but was either insufficiently documented owing to technological limitations or simply disregarded by recent reviewers.
It is beyond the scope of the present paper to analyse the potency issue in detail, but the following points may be considered here:
(a) Owing to the large biological and chemical variability of the cannabis plant, the variability of the marketed products is also, of necessity, very large. Furthermore, significant annual variations in potency have been noted under carefully controlled conditions [15, 17, 21, 51, 53], implying similar variations under natural conditions. In addition, there have been and continue to be changes in the nature and relative shares of the various cannabis products on each major cannabis market. All these factors naturally warrant careful consideration in any assessment of average product quality on a given market;
(b) As noted above, reliable laboratory techniques and adequate reference standards have only been available since the 1970s. The direct comparability of the results of different studies is further limited by virtue of differing assay techniques (gas chromatography, measuring total cannabinoid values, versus high-performance liquid chromatography, measuring separately two groups of cannabinoids, the neutrals and the acids [18, 20, 23, 50]). Therefore, the validity of any retrospective effort directed towards a comparative assessment of product potency over a period of several years, or decades, will necessarily be limited, especially where the data relate to the l970s and 1980s. Any reference to decades prior to the sixties will essentially be anecdotal in nature, based on descriptions of production practices and medical observation of cannabis consumers [51, 52];
(c) Whatever the particular situation in selected countries or in any given year, two significant developments clearly confirm the suggested gradually increasing cannabis product qualities and potencies over the past twenty to thirty years.
The first such development is the sequential emergence and continuing presence or expanding market share of new cannabis products with increasing average potencies (figure V). The three classic products (cannabis leaf, female plant tops and the resin) have gradually been supplemented by products such as Thai or Buddha sticks, and various types of hashish oil and sinsemilla. As noted above, such an evolution has necessitated gradual advancements in cultivation and production techniques. All these products were put on the illicit market with increasing quality and potency claims, and the production of "Netherweed" appears in this sequence simply as the latest, and most logical, evolutionary step.*
Thus, whatever the particular and usually short-term trend in the average or individual potencies of the classic cannabis products, the global trend in both production and consumption is towards increasingly potent products. At the same time, particular national or regional situations may depart considerably from this general trend.
Perhaps the most intriguing issue with the broadest policy implications is the question of whether the translocation of illicit cannabis cultivation and production to technologically advanced areas will continue in the future. If it does, we must consider what impact it will have on global production patterns and what means are available to counteract the continuation of such shifts. We must also consider the significance of these new developments in terms of priority for Governments and for international drug control bodies. Previous sections of this paper have briefly discussed some consequences and possible future scenarios; further policy-relevant issues are presented below.
First, it has to be recognized that what is seen today as a new trend in cannabis cultivation is a process that is neither completely new nor isolated in the illegal drug sphere. Experimentation in illicit drug manufacturing has a history on almost every continent. Yet the process seems to be gaining in intensity and diversity as well as geographic spread. As outlined above, the latest qualitative phase (indoor cannabis technology) is relatively new but expanding quickly. There is little to prevent it moving into, or closer to, some of the traditional cannabis-growing countries, where most of the new technology requirements would be readily available. There can be little doubt that the high supply-side incentives are more than sufficient to initiate such a process. Considerably decreased distances between the actual producers and consumers, both in the distribution and in the financial chain; quick and high financial returns; and increasing independence from traditional agricultural practices all substantially reduce the overall risks and further increase the financial returns on the supply side. According to some assessments, the total market value of netherweed produced in Holland in the last few years and the financial returns on it compete easily with those for tomatoes and tulips . It could easily be postulated therefore, that, on the basis of supply considerations alone, the trend is bound to continue.
It should be noted here that there are a number of concomitant developments in the production of the other major clandestine drugs. A brief comparison of the main attributes (see figure III and reference 37) shows that the "technology revolution" in illicit cannabis production has many parallels in clandestine synthetic drug manufacturing. Apart from the numerous technical and operational similarities, there appears to be one which, despite considerable policy relevance, does not seem to have received sufficient attention in the global policy discourse. It should be recalled that all these new developments in fact originated in the so-called "consumer" countries and until now have operated almost exclusively in those countries. With the "consumers" becoming increasingly their own "suppliers", and the suppliers of their neighbours as well, the conventional model of the global drug market now seems to have less relevance. As long as such situations were only sporadic and affected either a few traditional producer countries or a few industrialized consumer countries, the issues could have been rated as marginal and of limited significance; or, alternatively, as national problems with little international significance. However, the difficulty with such pragmatic judgements has always been that emerging new problems have frequently been neglected until they reached truly international dimensions, thus compromising the outcome of any counteraction at such a late stage. One has only to recall the cocaine forecasts and accompanying discussions of the 1980s, when Europe did little to prevent it becoming the "drug of the year" in 1988, hoping that the cocaine problem would remain exclusively American. The recent history of the present European ecstasy and stimulant waves could be another case in point.
An intriguing question is how to limit or counteract the strong driving influence of advanced technology, both material and information, on illicit cannabis cultivation and on consumption. The issue is, of course, much broader than this might suggest. With easy access to new technologies and information, it is ultimately personal choice and social opportunity that determine how, and for what purpose, those technical tools are utilized. Promotion of drug abuse is but one of the many areas (pharmaceutical and medical advertising, terrorism, criminal finance, child abuse and pornography) in which those great achievements of modern society may be misused. The issue is on the international discussion agenda, and specific remedial measures have been proposed and/or introduced by individual countries for particular subjects. Recent reviews highlight the negative role of modern technology in the rapid spreading of synthetic drugs [37, 56] and suggest a few areas for national and intergovernmental action. It remains to be seen how such thematically and geographically fragmented initiatives in a globalizing world will prove efficient without addressing some of the fundamental issues in a more generic manner.
As much as the control of precursors and of manufacturing equipment in the spirit of the 1988 Convention may prove an effective instrument for containing the global supply of most illicit drugs, they are practically irrelevant for cannabis. Such controls were originally designed as strategic tools for limiting access to specific equipment and material used in the extraction, refining and/or synthesis of illicit drugs and widely used by legitimate chemical and pharmaceutical industries. Extending this approach into areas of modern agricultural and gardening equipment and material would not only drastically extend the scope of controls into completely new areas, but would probably weaken rather than improve national compliance with that system as a whole. Also, the inherent weaknesses of such an approach are more than obvious in a global drug control environment, where cannabis tends in most consumer countries to receive lower control priority than heroin, cocaine and amphetamines. This happens despite the widely recognized fact that cannabis is by far the most frequently abused illicit drug worldwide. Such an attitude usually rests on a broad and rather vague understanding of the illicit cannabis market as it was in the past. Recent efforts by Interpol and by a few concerned governments [28-31] appear to have little effect in this respect. This general perception is unlikely to change until the potentially far-reaching impact of the new developments in cannabis production are recognized as one powerful factor in the transformation of illicit drug markets.
It is to be hoped that the sporadic initiatives will ultimately generate a significant change in present attitudes vis-a-vis the cannabis problem and, indeed, the illicit drug problem as a whole. Otherwise, with rapidly growing volumes and market shares of locally produced and often exported cannabis and other illicit drug products, industrialized consumer countries appear to have less and less moral and legal justification in calling for effective crop reductions in the traditional growing (producer) areas. A rethinking and course correction is needed in the first instance in those countries where the present trends originate and actually culminate. Such a process could in the broadest sense also contribute to a better understanding of such sensitive issues as supplier and consumer responsibilities.
While supply-side forces may be very powerful, it is ultimately consumer market preferences and opportunities that will largely determine how the new cannabis story unfolds in the future. A recent analysis of the cannabis consumer market in the United Kingdom  concluded that it seems to be a "mature" market, with steadily expanding numbers of consumers who make informed choices between different brands of the same product. Some brands have increased their market share thanks to publicity and consumer preference. This seems to be the situation at present in many countries of Europe and, according to recent reports on cannabis consumption, in North America as well [27, 28]. The phenomenon adds an extra dimension to the much discussed issue of the responsibility of "consumer countries" in the development of illicit drug markets.
A more specific technical question is how to handle, in the new drug consumer environment of Europe and North America, the various types of cannabis cultivation and the increasing spectrum of products, both licit and illicit. It has to be stressed that there has never been in this respect such a complicated and confusing situation as the one prevailing widely in Europe. Formerly, when there was significant industrial fibre hemp cultivation in a number of European countries, cannabis as a drug of abuse was little known in those countries; and when the latter was "discovered" and established in Europe, licit hemp cultivation was already virtually extinct [1-4]. Today, when we are experiencing the beginnings of a possible resurgence of licit hemp for a growing range of agricultural and industrial uses, the drug environment is radically different and most countries have the entire spectrum of cannabis plants (licit, illicit, wild, indoor) and the corresponding products within the same environment. To prevent potential licit-to-illicit shifts or other misuse, a regulatory system for licit cannabis cultivation was instituted for the first time by the European Union in the early 1980s and gradually adjusted to the new conditions (for details see the separate paper on this subject in the present issue). Some European countries, for example Hungary, go further in regulating their domestic agricultural and industrial production and trading in licit hemp. The significant elements of these new regulatory efforts are the following:
(a) The establishment of licensing procedures of some kind within an integrated agro-industrial system;
(b) Centralized production and supply of seed material guaranteeing uniform low THC levels in the plants;
(c) The assignment of responsibility for supervision, for safeguards against potential misuse and for compliance with quality requirements (mandatory use of the authorized and centrally distributed seed material);
(d) The extension of penal sanctions for non-compliance with or abuse of the above provisions.
Thus, the new developments are reflected in technical terms in the new emphasis on controlling the supply of cannabis seed, a pragmatic step in regulating licit agricultural cultivation. Many countries have put the seed and the leaves under the same national legislative control as the drug material, thus going far beyond the requirements of the international control system. However, this is much less effective when the plants are grown indoors from cuttings.
The "wild cannabis" phenomenon is usually of limited relevance to the cannabis supply situation in countries where substantial cultivation for drug production continues to take place. However, naturalized cannabis has occasionally served in the past as a cheap and easily available supply substitute. This has been the case in recent times in the countries of central and eastern Europe and the former Soviet Union, where the collection and consumption of locally grown herbal cannabis has contributed to the establishment of local illicit cannabis markets. In addition, the presence of extensive "wild cannabis" pockets in national territory may discourage governmental crop reduction and eradication efforts. The phenomenon may actually assume considerable dimensions in countries where licit or illicit cultivation has for some reason or other been discontinued and the case has been forgotten. Such typical situations have previously been seen in the United States and in other countries too.
In the case of the huge wild cannabis populations recently "discovered" in the Central Asian republics of Kazakhstan, Kyrgyzstan and Tajikistan , cannabis had escaped and gradually expanded over several decades, thanks to favourable conditions, following extensive licit hemp cultivation before and during the Second World War. This plant population ultimately reached enormous dimensions, possibly comparable to the total cultivated areas of some of the biggest cannabis producer countries, in the Chu valley, other regions of Kazakhstan and, to a lesser extent, neighbouring countries also.
The principal reason for concern in most countries where sizeable naturalized cannabis growth ("wild cannabis") has been noted lies in its confusing effects and the potential for a multiple synergy with actual illicit cannabis cultivations and trafficking, rather than the significance of such growth in global terms. Excellent examples for these confusing effects are provided in the national reports of most central European countries, which make frequent reference to the numbers of living plants seized or to "home-grown", "wild-grown" and "native" cannabis as a major problem. The technical difficulties and the resulting confusions for both the enforcement and the judicial systems are evident. For example, the continued references to large quantities of illicit cannabis collected from "wild cannabis populations" in the Central Asian republics may easily mask for quite some time the existence of sizeable actual illicit cultivation in the same geographic area. It is disturbing that no one can even approximately determine in these regions the nature and origin of the cannabis products: how much is collected from "wild" populations, what is the extent and trend of actual local cultivation and what is the output level, market share and pattern of transit trafficking from the main producer neighbours through these countries to Europe. Ultimately, the result is a high risk that a major new supply subregion will gradually become superimposed on the existing enormous hashish supply from Afghanistan and Pakistan. Some suggestions specific to the Central Asian case have been made in .
Where remedial measures against the expansive growth of wild cannabis are considered a priority, several options are available for consideration, the essential starting point for each one being a fairly accurate knowledge of the actual national cannabis supply situation. However, national and aggregated global assessments of illicit drug production, trafficking or consumption are not noted for their reliability. The difficulties and inherent limitations of this exercise have often been the subject of critical comments [57, 58]. Cannabis is in many ways a particular case with its own additional limitations, so that the reliability of reported data is refuted more often than confirmed by subsequent assessments. Two recent studies of the United States cannabis market [24, 25], which is probably the best studied illicit drug market worldwide, provide excellent documentary evidence of the situation. Both studies make considerable corrections to previous national assessments.
Many of the cannabis-specific limitations have been mentioned in previous sections. The one that deserves further discussion is the growing uncertainty brought about by the increasing variance in the potency of the cannabis products consumed in a number of countries.
All illicit drugs are marketed and consumed in a range of purities, strengths and potencies, which are most often unknown. The potency of herbal cannabis appears to be growing, from as low as 0.5-1.0 per cent THC to as high as 20-30 per cent, resulting in potency multipliers as high as 40 to 60. This fact is neither expressed in any data on cannabis weight or volume, nor in reports on local or national cannabis markets. Production and seizure volumes are simply subsumed within the unqualified cannabis herb or resin categories. In contrast, heroin and cocaine production and trafficking estimates are usually based on the triangulation system for the assessment of cultivated areas, estimated yields of both the crude and the purified/converted products, and quantities of the conversion products trafficked (wholesale and retail level purities often being shown separately), based on seizure and laboratory analysis data. Aggregate figures are then expressed in more precise terms, such as raw material (coca leaf, opium) quantities with the average content of active principle, or purified/converted products with purity data.
Since illicit cannabis is only marketed in the form of various crude products and the number of cannabis seizures is high in most countries, there is much less emphasis on and hence legal requirement for exact laboratory data on the THC content of the products. Such analyses are performed in relatively few countries and only for particular drug seizures. Technological impediments, such as the fairly restricted availability of pure standards for the cannabinoids and the wide conceptual and experimental diversity of laboratory assay techniques, further limit the cross-national comparability of cannabis assessments. Improvements have been proposed in the literature and introduced in particular agency reports [18, 20, 23, 28, 32, 49, 50]. Some of these steps forward consist in more accurate characterization and categorization of the origin and nature of seized cannabis products; more reliable seizure procedures; and a new approach to assessing and comparing illicit traffic and consumption data by converting and expressing them in THC equivalents. The last is rather demanding technologically and feasible in a few countries only. Nevertheless, recent policy developments in some of the more advanced consumer countries make it necessary to develop laboratory-based differentiation between "small quantities" of cannabis for personal use and "large quantities" for distribution and trafficking. In turn, such developments further highlight the urgent need for a central mechanism to serve as a platform for harmonizing, if not standardizing, the various cannabis assay techniques, thus providing a basis for widely accessible and reliable laboratory assay technology, equipment and chemical reference material.
For decades, cannabis has been seen as the most "conservative" of illicit drugs, with little or no significant qualitative change in cultivation, product quality and consumption patterns and with a low-to-moderate health and social risk to the consumer. It appears that, as in many other areas of human activity, it is technological progress that may radically alter this relatively convenient situation and may force a reassessment of individual and collective attitudes to this drug.
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