A survey of the potency of Japanese illicit cannabis in fiscal year 2010
Yukari Tsumura a,*, Rikiya Aoki b, Yoshio Tokieda c, Mamoru Akutsu d, Yasuharu Kawase e,
Tadashi Kataoka f, Toshiyuki Takagi g, Tomomi Mizuno h, Masakatsu Fukada i,
Hiroshi Fujii j, Kazumi Kurahashi k
In recent years, increased ‘cannabis potency’, or D9-tetrahydrocannabinol (THC) content in cannabis
products, has been reported in many countries. A survey of Japanese illicit cannabis was conducted from
April 2010 to March 2011. In Japan, all cannabis evidence is transferred to the Minister of Health, Labour
and Welfare after criminal trials. The evidence was observed at Narcotics Control Department offices in
major 11 cities.
The total number of cannabis samples observed was 9072, of which 6376 were
marijuana. The marijuana seizures were further classified, and it was found that in terms of the number
of samples, 65.2% of them were seedless buds, and by weight 73.0% of them were seedless buds. Seedless
buds were supposed to be ‘sinsemilla’, a potent class of marijuana. THC, cannabinol (CBN) and
cannabidiol (CBD) in marijuana seizures exceeding 1 g were quantified. The number of samples analyzed
was 1115. Many of them were shown to contain CBN, an oxidative product from THC. This was a sign of
long-term storage of the cannabis and of the degradation of THC. Relatively fresh cannabis, defined by a
CBN/THC ratio of less than or equal to 0.1, was chosen for analysis. Fresh seedless buds (335 samples)
contained an average of 11.2% and a maximum of 22.6% THC. These values are comparable to those of
‘high potency cannabis’ as defined in previous studies. Thus, this study shows that highly potent
cannabis products are distributed in Japan as in other countries.
