Thread by @publicaddress

1. Firstly, this column is written in good faith. The authors do clearly care. But it's full of bad arguments and in places, false claims. Let's go through some of them ...

https://twitter.com/TheSpinoffTV/status/1316131870698999808

2. The column places great weight on a quote from Sir Robin Murray that 8% of people who use high-potency cannabis daily will develop schizophrenia. Further down, this elides into being 8% of *all* users of high-potency (ie: modern) cannabis, which isn't what he said.

3. Sir Robin hasn't said this in any publication I can find. In this 2018 summary, he quotes an evidence review finding a fourfold risk of developing psychotic symptoms *for the heaviest users*, vs non-users. (The cited review doesn't define heavy use) researchgate.net/publication/32…

4. So among 100,000 of the heaviest cannabis users, there would be about 4000 who developed psychotic symptoms, *including schizophrenia* (nb: the review doesn't give an odds ratio for schizophrenia itself). That's not great. It's also not what the column claims.

5. It is notable that Sir Robin regards criminalisation as "foolish". He writes of legalisation in the above 2018 paper that it would be wise to "watch what happens in the next few years as different models of legalisation are implemented in differ-ent states in North America."

6. The recent evidence is that adolescent use (where everyone agrees most of the risk is concentrated) has been stable or, more likely, falling in legal jurisdictions. And that rates of youth cannabis use disorder are falling *faster* in the legal states than elsewhere.

7. It would also have been interesting to ask Sir Robin to comment on the proposed model in New Zealand, where the THC and CBD content of regulated cannabis flower would be displayed – and would also have a bearing on excise and hence price.

8. This is relevant because, as Sir Robin has repeatedly stated, CBD ameliorates the risks of THC. It is the black-market breeding of cannabis over 30 years that has driven CBD content down and THC up. A "no" vote is a vote for that to continue.

9. And it will continue. THC concentrates (80%+ THC) are appearing in the illicit NZ market. Now would actually be a *really good* time to introduce a potency-limited legal alternative based on cannabis flower. People aren't going to stop using cannabis. We *could* make it safer.

10. Finally, the authors of the Spinoff column would like to see warnings about psychosis risk included on the labelling of legal cannabis. But there only way there will even *be* labels is if we vote "Yes".

10a. I see @DrSureshMuthu is also very unimpressed and will be writing a response for The Spinoff covering some of the risk stuff I'm not competent to comment on. That will be worth reading.