A few weeks ago this blog carried a critique of a BBC programme about cannabis called “How drugs work” – read it here. The programme contained a misleading and wrong claim:

Skunk is the name given to genetically engineered weed designed to deliver the maximum does of mind altering THC

This is going further than “genetically modified” which is a description that has been used quite a lot recently to describe “skunk” type cannabis and has even found it’s way into peer reviewed scientific papers. One such paper was written by Dr Celia Morgan, a Research Fellow in the Clinical Psychopharmacology Unit of  Clinical Health Psychology at University College London. She used the term in a paper entitled Cannabinoid combination affects cannabis-linked psychological symptoms, reviewed here in April 2008

there are higher levels of D9-THC in ‘skunk’ or genetically modified strains of the plant.

This, along with other issues raised in that paper lead to an exchange of e-mails between Celia and myself which produced an interesting result. Regarding the GM claim the exchange was as follows:


As an aside I am also somewhat surprised to see your use of the term “Genetically modified” in relation to cannabis. You should be  aware that no cannabis is genetically modified and I’m simply amazed that error wasn’t picked up by peer review.

Celia replied:

In relation to your second point, the term ‘genetically modified’ was not meant in the way it is used in the media today, i.e. in relation to the so-called franken foods. Farmers have been ‘genetically modifying’ crops i.e. cross-breeding them to get better strains, for centuries. We meant to imply that skunk is a cross-bred plant, which may possibly have been bred to have a higher THC content. This, in scientific terms does constitute genetically modifying something, as you are indeed modifying its genetics.

I replied:

Sorry to come back on this point again, but it is very important.

(snip the text above which I quoted in the e-mail)

But the plant is still cannabis, all of the genes it contains are cannabis genes.

To my surprise GM doesn’t in fact appear to be a very scientific term. I looked for a definition in several genetics text books in the library at work and couldn’t actually find one. I did though find this definition from a google search for ‘define: Genetically Modified’:

> A genetically modified organism (GMO) is an organism in which the
> genetic material has been altered in a way that does not occur
> naturally by mating and/or combination.

Several similar definitions are also given for GMO.  That being the case it would seem to support my view that the term GM specifically does not include selective breeding.

I hope you can appreciate why this is important and is not just a matter of semantics. Over the past few years there has been much mis-reporting in the tabloid – and even quality end – of the press and if such terms as GM are used in scientific publications without being challenged the press will feel justified in doing likewise.

I would like to ask that you correct this unintentional error please.

To which Celia replied:

Hi Derek,

I see your point now and agree that describing cannabis as ‘genetically modified’ could be used negatively in the media. I will write to the journal and ask them to print and erratum.

Very best wishes


What makes this interesting is that the claim that “skunk” is “genetically modified” was made in the BBC programme at around the point where Celia Morgan was interviewed, although the claim was not attributed to her.

A contributor to another cannabis forum has made a compliant to the BBC regarding this use of the term “genetically engineered” and has had a reply from the BBC

“The ‘How Drugs Work’ production team have confirmed that having discussed this issue with the experts who helped with the progs, we can say that ‘Skunk’ has been grown from strains inbred to produce increased levels of THC.

This involves genetic changes, therefore it is genetically modified though not in the sense the term is used for foodstuffs. This research has been reviewed by a member of the Advisory Council on the Misuse of Drugs and Professor of Psychopharmacology.”

The term used in the programme was “genetically engineered”, which certainly implies human interference with the genetic code. But in any case  selective breeding does not bring about genetic changes, this is simply wrong. It can add nothing to the plants genes which is not already there, it is, as the name indicates, simply a process of selection. As Celia was involved in the programme and the explanation given by the BBC is so similar to her explanation to me in 2008, it would seem a  fair bet she is the origin of that claim, but of course we have no way of knowing.

The issue is not simply one of semantics however, as Celia seems to have accepted in her e-mails to me. Genetically modified is a highly emotive term, implying the use of a technology which is widely mistrusted by the public. It’s inclusion in a supposedly factual programme like this is bad enough, if it’s being done under the guidance of a respected expert in the field is especially worrying. This is even more so as it’s used to underline the claims of harm to mental health from cannabis use, adding to the reefer madness scare.