The policy on cannabis use in The Netherlands is substantially different from that in many other countries. It is based on the idea that separating the markets for hard drugs and soft drugs prevents soft drug users to resort to hard drug use. Over the years so-called coffeeshops emerged.
Coffeeshops are alcohol free establishments where the selling and the use of soft drugs is not prosecuted, provided certain conditions are met. Many of the cannabis products sold in these coffeeshops originate from Dutch-grown grass called 'nederwiet'. Critics of the Dutch drug policy have claimed that the THC-content of nederwiet has increased drastically over the last decades. However, the THC-content of cannabis products as sold in coffeeshops had not systematically been tested. On request of the Ministries of Health and Justice, the potency of cannabis products as sold in coffeeshops in The Netherlands has been investigated since 1999.
Δ9-Tetrahydrocannabinol (THC) is the main psychoactive compound in marihuana and hashish. The aim of this study is to investigate the concentration of THC in marihuana and hash as sold in Dutch coffeeshops. In addition it was studied whether there are differences between the cannabis products originating from Dutch grown hemp (nederwiet) and those derived from imported hemp. It is the tenth year that this study has been performed. Apart from THC, the content of two other cannabinoids, cannabidiol (CBD) and cannabinol (CBN), has been studied.
The names and addresses of 50 Dutch coffeeshops were randomly selected. For the purpose of this study, 66 samples of nederwiet (Sinsemilla), 15 samples of imported marihuana, 16 samples of Dutch hash and 56 samples of hash prepared from imported marihuana were anonymously bought in the selected coffeeshops. In addition, 49 samples of the most potent (herbal) marihuana product available in the coffeeshop, were bought*10. As a rule samples of 1 gram were bought.
The average THC-content of all the marihuana samples together*11 was 16,7% and that of the hash-samples 22,0%. The average THC-content of nederwiet (17,8%) was significantly higher than that of the imported marihuana (7,5%). Hash derived from Dutch hemp contained more THC (32,6%) than hash originating from foreign cannabis (19,0%). The average THC-percentage of nederwiet was higher in 2010 than in 2009 (17,8 vs. 15,1%). The THC-percentage in foreign marihuana was significantly lower than the year before (9,9% in 2009 vs 7,5% in 2010). The average THC-percentage of the marihuana samples that were bought as most potent (17,9%) did not differ from that of the most popular varieties of nederwiet. Nederwiet contains significantly less CBD than imported marihuana.
Prices that had to be paid for foreign marihuana were lower than those for any of the other cannabis products. The prices of nederhasj were higher. The average price for a gram nederwiet increased from 2007 to 2009 (up to 50%), but last year prices remained at the level of 2009.
*10 Most potent as indicated by the coffeeshop personnel.
*11 This is not corrected for in terms of relative contribution of number of foreign or Dutch samples.