A note on the cannabinoid content of Jamaican ganja

Sections

Sample characteristics
Analytical procedures
Results
Summary
Acknowledgements

Details

Author: Joan A. MARSHMAN, , Robert E. POPHAM ,, Carole D. YAWNEY
Pages: 63 to 68
Creation Date: 1976/01/01

A note on the cannabinoid content of Jamaican ganja

Joan A. MARSHMAN, 1
Robert E. POPHAM 1,
Carole D. YAWNEY 2

In 1971, a WHO Scientific Group noted the increasing feasibility and importance of studies of long-term cannabis users to complement the knowledge gained through short-term experimental research [ 10] . In the same context, the Group recognized the need for data on the cannabinoid content of representative samples of the cannabis consumed in different parts of the world, to the end that the epidemiological significance of reported chronic effects could be more adequately assessed. Thus, the concentration of the active principle (THC) is known to vary considerably from one area to another, and for that matter, also within the same area [ 1] .

The aim of the present note is to report the results of a chemical analysis of cannabis samples from Jamaica, and to examine the variation found in these samples. In recent years Jamaica has attracted particular attention in connexion with studies on effects of chronic cannabis use. Probably this is mainly because it is one of the very few countries with a sizable population of traditional cannabis users, who are more or less readily accessible to investigators for both clinical and field studies. Several such studies have been reported, for example, by Hall [ 3] , Prince et al. [ 6] , and most recently, by Rubin and Comitas [ 7] .

To date, only Rubin and Comitas have reported on cannabinoid content, and their data were limited to 29 pairs of samples provided by the subjects of a clinical investigation. 3 In the present study, sampling was of a more general character. The samples were obtained from various cannabis dealers in Kingston and elsewhere, and represented the produce of different seasons and different cultivators. Accordingly, the analytical results serve to indicate the extent to which the data of Rubin and Comitas accurately reflect the content-and variation in content-of the cannabis customarily consumed in Jamaica.

Sample characteristics

The samples were obtained by one of us (C.D.Y.) towards the end of an ethnographic study. In the course of the field work familiarity was acquired with many of the "yards" where cannabis - or "ganja"as it is called in Jamaica - is purchased and smoked, and good rapport was established with a number of dealers. 4 In all, 36 samples were purchased from these dealers at two different periods: 20 samples in the first three weeks of April and 16 samples at the beginning and end of July. At the time of each purchase, the dealer was asked when the ganja had been harvested, what type of fertilizer had been used, and how the harvest had been cured.

1Addiction Research Foundation, 33 Russell Street, Toronto, Canada.

2Department of Anthropology, York University, Toronto, Canada.

3 Each subject was asked to provide two samples of the cannabis used so that the total amounted to 58 samples. However, the THC concentrations of the samples in each pair were identical or nearly so in every case. This indicated that there were, in effect, only 29 independent samples.

4 Accounts of the beliefs and practices of Jamaican ganja users may be found in Kintzinger [ 4] and Smith et al. [ 8] . Data respecting the history, extent and mode of use in the country, motives for use and personal and social characteristics of users have been reported by Prince et al. [ 6] and by Rubin and Comitas [ 7] .

The April samples had been harvested mainly towards the end of February or in early March, following 5 to 6 months growing time. Locally, April was considered to be one of the best months in which to buy ganja, although not quite as good as the December-January period. July, on the other hand, reflected an inter-crop period when the ganja was said to be of poor quality. Some of the July samples were reportedly derived from ganja harvested many months previously, some from a second harvest, and some from immature crops.

All of the crops represented by the samples evidently had been fertilized. In some cases an inorganic fertilizer had been used, and in others, an organic fertilizer such as cow, chicken, or occasionally, bat manure. In this connexion, it is noteworthy that, in the local view, producers of poor quality ganja were more likely to use inorganic fertilizers.

Some cultivators simply re-planted their fields at the time of harvest, while others first planted the cannabis seeds in boxes and transferred the plants to the field when about a foot high. Harvesting normally occurred when the leaves had begun to curl and the seeds appeared. Typically, the plant was cured by sun-drying for several days until it acquired a rich brown colour. At least some of the cultivators then stored the ganja in air-tight containers until sold to the dealers. However, the latter commonly kept their stock in open tins (with the probable result that some loss in potency occurred).

All but two of the samples were drawn from ganja intended for smoking, and included the principal types believed by users to reflect differences in quality. These were: bush weed, considered to be the poorest type; average weed or seedy bush; and cully (probably from the Hindu god "Kali"), which comprised the flowering top of the plant, and was considered the best ganja. The two exceptions were samples of green (i.e., uncured) ganja which, when made into a tea or mixed with rum, was widely used in folk medicines as a treatment for a variety of complaints [ 6] .

The samples ranged from 0.5 to over 6 grams in weight, most being between 1 and 3 grams. To prevent water loss and minimize enzyme activity, each sample was heat-sealed in a polyethylene envelope, and with a few unavoidable exceptions, was refrigerated until mailed to the laboratory in Toronto.

Analytical procedures

The extraction procedure employed was based on modifications of the methods of Patterson and Stevens [ 5] and Turk et al. [ 9] . A sub-sample of 50 mg of cannabis was weighed into a 7 ml glass-stoppered test tube, and 2.0 ml of petroleum ether (b.p. 37°- 46°C) containing 5 cholestane as an internal standard in the concentration: 0.5 mg/ml, were added. The mixture was allowed to stand at room temperature for 5 minutes, then mixed on a Vortex Mixer for one minute and again allowed to stand for 5 minutes. The preparation was mixed for two additional one-minute periods with 5-minute periods of standing following each. Extraction was carried out on duplicate 50 mg aliquots of each cannabis sample.

Preliminary experiments indicated that this procedure extracted Δ 9-tetrahydrocannabinol quantitatively from cannabis samples.

Triplicate 1 μ aliquots of the supernatant petroleum ether extract were analysed using a Varian Model 2100 gas chromatograph equipped with flame ionization detectors and a Varian Model 20 recorder with a range of 0-1 ml. The gas chromatograph was fitted with a Pyrex column of 6.0 mm OD, and 4.5 ft in length, packed with U.C. W-98 3.8 per cent on Gas Chrom Q 80/100 mesh. Before use the columns were conditioned as follows: 1 hour at 250°C with zero nitrogen flow, then 16 hours at 250° C with zero nitrogen flow, then 16 hours at 250°C with nitrogen flow at a rate of 40 ml/min. The following conditions were used during the analysis: injector, column oven, and detector temperatures were 250°,265°, and 275°C, respectively, and flow rates of nitrogen, hydrogen, and air were 40, 40, and 260 ml/min, respectively. Under these conditions, the retention times of cannabidiol, Δ 9-tetrahydrocacannabinol, and cholestane were 1.75, 2.21, 2.59, and 5.53 minutes, respectively. Standard curves were prepared using pure reference samples of cannabidiol (CBD), Δ 9-tetrahydrocannabinol and cannabinol (CBN) over the range 0.25 to 4.0 μg/μl with cholestane at 0.5 μg/μl as internal standard. When the ratio: height cannabinoid peak/height cholestane peak was plotted versus: μg cannabinoid/μg cholestane, linear curves were obtained over the concentration range employed.

Prior to extraction, the seeds were removed from each sample to be analysed. However, in practice, ganja pipe smokers do not manicure the cannabis received before using it. The cannabis is simply kneaded into a cake with a little water, and sometimes tobacco is added. "Spliffs" or ganja cigarettes are rolled dry and a little manicuring may occur, although, if the material is a good cully, the smoker usually does not tamper with it. Since the cully bud is naturally tightly curled when mature, the seeds tend to be retained. When ganja tea is prepared, all parts of the plant are used; only boiling water and sugar are added. Accordingly, the present data on cannabinoid content were expressed as percentages of the weight of the total sample received. It was felt that such percentages would give a better approximation to the dose actually delivered in a given quantity of cannabis used. This mode of calculation involved the assumption-supported by the findings of Fetterman et al. [ 2] -that the cannabinoid content of seeds is negligible.

Results

The concentrations of cannabinoids, season of purchase, type of fertilizer used, and the quality of the cannabis according to local standards, is shown for each of the 36 samples in table 1.

The THC concentration ranged from little more than a trace to almost 8.0 per cent. However, the distribution is positively skewed and concentrations of 4.0 per cent or more were comparatively rare (6 out of 36). The mean of the distribution is 2.8 per cent, the median is 2.3 per cent and the mode below 2.0 per cent. These results agree very well with those of Rubin and Comitas (7, App. III). Their samples ranged in THC content from 0.7 per cent to 10.3 per cent with a mean of 2.9 per cent and a median of 2.6 per cent. Concentrations of 4.0 per cent or more were likewise infrequently encountered (4 out of 29 pairs).

The seasonal difference in sampling is clearly reflected in the THC concentrations as shown in table 2. Over-all, the spring samples were nearly two-and-a-half times as potent as those obtained in mid-summer. And some of the within season variation would appear to be attributable to the type of fertilizer used: the use of organic fertilizers is associated with a somewhat higher median THC content in both months. However, a selective factor may be involved since, as noted earlier, persons known to produce poor-quality ganja were said to be more apt to use inorganic fertilizers.

TABLE 1

The Δ9-tetrahydrocannabinol, cannabidiol and cannabinol content (per cent W/W), and other characteristics of 36 Jamaican ganja samples

Sample

No. Δ9-THC

CBD

CBN

Season

Fertilizer

Quality

10 0.04 0.04 0.54
July
Organic
Cully
11 0.63 0.08 0.36
July
Inorganic
Bush Weed
1 0.88 0.09 0.26
July
Inorganic
Aver. Weed
3 0.99 0.11 0.23
July
Inorganic
Bush Weed
5 1.07 0.11 0.33
July
Organic
Aver. Weed
12 1.19 0.10 0.21
July
Inorganic
Bush Weed
9 1.21 0.05 0.13
July
Organic
Cully
14 1.31 0.04 0.18
July
Inorganic
Aver. Weed
6 1.40 0.11 0.24
July
Organic
Aver. Weed
7 1.41 0.13 0.04
July
Inorganic
Bush Weed
25 1.62 0.14 0.29
April
Inorganic
Aver. Weed
24 1.76
<0.1
<0.1
April
Inorganic
Aver. Weed
13 1.87 0.17 0.29
July
Organic
Cully
4 1.93 0.14 0.32
July
Organic
Cully
30 1.96 0.10 0.61
April
Organic
Bush Weed
31 1.97 0.12 0.49
April
Inorganic
Bush Weed
2 2.07 0.12 0.66
July
Inorganic
Aver. Weed
23 2.24 0.11 0.18
April
Inorganic
Aver. Weed
34 2.35
-
0.23
April
Inorganic
Aver. Weed
27 2.46 0.20 0.32
April
Inorganic
Aver. Weed
15 2.50 0.13 0.26
July
Organic
Cully
8 2.52 0.20 0.08
July
Inorganic
Bush Weed
16 2.76 0.05 0.29
July
Organic
Cully
33 2.95
-
0.33
April
Organic
Aver. Weed
32 2.98 0.11 0.18
April
Inorganic
Bush Weed
29 3.23 0.14 0.35
April
Organic
Aver. Weed
22 3.27 0.06 0.08
April
Organic
Green
28 3.41 0.15 0.61
April
Organic
Aver. Weed
26 3.68 0.21 0.45
April
Organic
Cully
17 3.87 0.10 0.97
April
Inorganic
Cully
21 5.10 0.05 0.12
April
Inorganic
Cully
35 6.52 0.10 0.11
April
Organic
Cully
20 6.59 0.20 0.11
April
Organic
Green
18 6.98
-
0.17
April
Organic
Cully
19 7.71 0.08 0.21
April
Organic
Aver. Weed
36 7.85 0.09 0.36
April
Organic
Cully

Finally, it is evident that local judgements of quality differentiated samples quite accurately as to THC content, although certainly not with infallible success. Thus, two samples labelled "bush weed" (Nos. 8 and 32) had more than 2.5 per cent THC, and one referred to as "cully" (No. 10) had the lowest concentration of any sample.

TABLE 2

Some sources of variation in the cannabinoid content of Jamaican ganja

 

THC content, per cent W/W

Source of variation

Number of Samples

Range

Median

Season
     
April
20
1.62 - 7.85
3.25
July
16
0.04 - 2.76
1.36
Fertilizer
     
April
     
Organic
11
1.96 - 7.85
3.68
Inorganic
9
1.62 - 5.10
2.35
July
     
Organic
8
0.04 - 2.76
1.64
Inorganic
8
0.63 - 2.52
1.30
Local judgment
     
Cully
12
0.04 - 7.85
3.22
Average weed
14
0.88 - 7.71
2.16
Bush weed
8
0.63 - 2.98
1.69
Green ganja
2
3.27 - 6.59
-

Summary

There has been considerable recent interest in the study of Jamaican ganja users as a potentially valuable source of information on the effects of long-term cannabis consumption. However, reported data on the cannabinoid content of Jamaican material have been limited to those of Rubin and Comitas for a small number of samples of unknown representativeness. In the present study, the cannabinoid content was determined on 36 samples purchased from various ganja dealers at two different periods, derived from crops treated differently with respect to fertilization, and representing the range of types locally considered to differ in quality or potency. The analytical results agreed well with those of Rubin and Comitas, and indicated that samples with a Δ 9-THC content of 4.0 per cent or more were apt to be comparatively rare. The median value was 2.3 per cent by weight. Some of the variation in the THC content of the samples was clearly attributable to the different seasons in which they were purchased, and some may have been due to differences in the type of fertilizer used in cultivation. Local judgement as to the potency of samples proved generally sound, although by no means infallible.

Acknowledgements

The authors gratefully acknowledge the technical assistance of Mrs. K.L. Adamson in the analyses of the samples. Reference standard samples of Δ 9-tetrahydrocannabinol and of cannabinol and cannabidiol were supplied by the Health Protection Branch, Health and Welfare Canada and the Battelle Columbus Laboratories, Columbus, Ohio respectively.

References

001

Commission of Inquiry into the Non-medical Use of Drugs. "Cannabis", Ottawa, Information Canada, 1972.

002

P.S. Fetterman, E.S. Keith, C.W. Waller, O. Guerrero, N.J. Doorenbos and M.W. Quinby. "Mississippi-grown Cannabis sativa L.: preliminary observation on chemical definition of phenotype and variations in tetrahydrocannabinol content versus age, sex and plant part", J. Pharmaceutical Sci. 60: 1246-1249, 1971.

003

J.A.S. Hall. "Preliminary studies on ganja smoking in Jamaica", The Practitioner 209: 346-351, 1972.

004

S. Kitzinger. "Protest and mysticism: the Ras Tafari cult of Jamaica", J. Scientific Stud. Religion 8: 240-262, 1969.

005

D.A. Patterson and H.M. Stevens. "Identification of Cannabis", J. Pharm. Pharmac. 22, 391-392, 1970.

006

R. Prince, R. Greenfield and J. Marriott. "Cannabis or alcohol? Observations on their use in Jamaica", Bull. on Narcotics, XXIV: 1, 1-9, 1972.

007

V. Rubin and L. Comitas. "Ganja in Jamaica: a Medical Anthropological Study of Chronic Marihuana Use", The Hague, Mouton, 1975.

008

M.G. Smith, R. Angier and R. Nettleford. "The Ras Tafari Movement in Kingston, Jamaica", Kingston, Inst. Soc. Econ. Research, 1960.

009

R.F. Turk, H.I. Dharir and R.B. Fornet. "A Simple Chemical Method to Identify Marihuana", J. Forensic Sci. 14: 389-392, 1969.

010

WHO Scientific Group. "The Use of Cannabis", Wld. Hlth. Org. Techn. Rep. Ser., No. 478, 1971. (Summary in Bull. on Narcotics, XXIV: 1, 11-19, 1972).