The final paragraph in this story precludes the Daily Mail from publi****ng
it.
Cannabis effects disupted
Date: 18/06/2008
Claims that a large increase in the strength of cannabis over the last
decade is driving the occurrence of mental health and other problems for
users are not borne out by a study of the worldwide literature, say
researchers at the National Drug and Alcohol Research Centre (NDARC) and
the National Drug Research Institute (NDRI), both from Australia.
Their conclusions, published in this month's issue of ADDICTION, are that
increased potency has been observed in some countries, but there is
enormous variation between samples, meaning that cannabis users may be
exposed to greater variation in the strength of the cannabis they use in a
single year than over years or decades.
Cannabis samples tested in the United States, the Netherlands, the United
Kingdom and Italy have shown increases in potency over the last decade,
but no significant growth in other European countries or in New Zealand
has been found during the same period.
THC is the active ingredient in cannabis, which produces the strongest
psychoactive effect. In the United States, the level of THC in confiscated
cannabis was 8.5% in 2006, up from 4.5% in 1997. Recent Dutch data show
that the THC of cannabis sold in coffee shops more than doubled between
2000 and 2004, but has since levelled off.
THC content varies according to the part of the plant that is used, the
method of storage, and cultivation techniques. Popular belief is that
hydroponic or other methods of indoor cultivation produce higher
concentrations of THC than occur naturally, but the jury is still out on
this issue.
The ability to control the indoor environment means that plants can reach
their full potential, which includes reaching the maximum level of THC.
The increase in market share of indoor-grown cannabis seen in Australia as
well as North America and Europe may have led to a more consistent product
which could explain the potency increases re****ted in some countries.
While some public debate has linked large increases in cannabis potency to
increased mental health problems, there are currently insufficient data to
justify this claim, and care ought to be taken when considering policy
decisions on this basis. Im****tantly, further research is required to
understand whether cannabis users can, or do, alter their intake in
response to a change in potency.
In their discussion of potential health risks, the authors point to
studies that observe that some cannabis smokers, when faced with a
'strong' product, act rather like tobacco smokers and adjust their dose by
increasing the interval between puffs, or holding smoke in their lungs for
a shorter period of time. This behaviour may reduce possible harms caused
by increased potency.
The authors also discuss the health risks of contaminants. Possible
contaminants include naturally occurring ones such as fungi; growth
enhancers and pesticides; and substances added for marketing purposes to
'bulk up' the weight. Lack of systematic monitoring for contaminants makes
an *****sment of risk difficult; it is im****tant to learn more about the
health risks of cannabis of ingesting contaminated cannabis - for example,
moulds are known to cause respiratory problems and lung disease.
The authors say "Given the relatively high prevalence of cannabis use it
is im****tant we have current, accurate information to help users make
informed decisions about their use, and that policy development and media
debate about the health harms associated with its use are guided by
research evidence rather than rumour."
http://www.scientistlive.com/lab/?/Pharmacology/2008/06/18/20573/Cannabis_effects_disupted/
--
Dr John Watson
Baker Street
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