The claim that "the tars in cannabis are considerably more dangerous than those in tobacco" is made in Patricks An Introduction to Medicinal Chemistry (4th edition, p. 169). It's just a simple one line statement and not much attention is given to it, but from what I already knew this is to say the least a very controversial statement (see for example the independent website about drugs Erowid) and I expect better for a frequently used University level book.

The question is to what degree (from a chemical point of view) there is truth (or falsehood) to this statement given current more or less objective (not like the Heath monkey studies) knowledge? Is the author in his right to boldly state this?

  • 4
    $\begingroup$ I think this is a good question. My worry is that some will feel it approaches "personal medical advice" and is thus off-topic, but I don't believe this is true. It is asking about the truth value of claims advanced by referenced documents in the chemical literature. On-topic. $\endgroup$
    – Curt F.
    Commented Jul 30, 2015 at 0:54
  • $\begingroup$ @CurtF. Thank-you. No it's not at all personal medical advice, I haven't smoked a joint in 4 years haha! I just noticed many many times conflicting statements regarding this, all from more or less reputable sources. This was kind of the last "drop" that made me decide, I want to know what is actually true and I want others to know what is actually true. For example on a Dutch (I'm Dutch) health website affiliated with the government I saw the claim that 1 joint equals 20 cigarettes, but of course no source. $\endgroup$
    – Jori
    Commented Jul 30, 2015 at 8:42
  • $\begingroup$ I seems that people have forgotten the scientific part of this claim (from a medical chemistry point of view) and only focus on the political impact. This is IMHO an excellent place to sort out the scientific part! $\endgroup$
    – Jori
    Commented Jul 30, 2015 at 8:44
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    $\begingroup$ I think this is fair game here and on topic, but it might be a bit broad for a good answer. If I see that correctly, an answer would have to first figure out what compounds will be inhaled in both cases and then rank them according to the physiological effect. Splitting it up in smaller pieces might be worth thinking about. Also you could probably get some more detail - at least for part of the problem (e.g. side effects of medical marijuana) - on health.se. But I don't know about their scope, so better check that first... $\endgroup$ Commented Jul 31, 2015 at 18:44
  • $\begingroup$ @Martin-マーチン For the sake of research I would absolutely agree with you of course. But splitting this question would be disastrous for it being useful as a point of reference. I think it's most on-topic here. I'm specifically looking for a chemical explanation of the claim rather than empiric experience. I'm going to two the following two things: 1) raise a 50 point bounty for attention and 2) contact the author of the mentioned book to see if he wishes to elaborate on the claim (after all, it is his book!). Thanks again Martin, good to see you on the mod team :) $\endgroup$
    – Jori
    Commented Aug 1, 2015 at 8:49

1 Answer 1


This is not a complete answer (merely a step in a particular direction, namely that of the falsehood of the claim), but I contacted the author of the book (Introduction to Medicinal Chemistry) Graham Patrick and he wrote the following:

Dear Jori,

Many thanks for your e-mail and observations. Unfortunately, that statement was made in a very early edition of the textbook published over ten years ago and so I doubt if I will be able to track down the original reference on which it was based. As you say there is controversy and the statement is too sweeping. Work on the 6th edition is starting this year and so it will be possible to modify that particular passage. Many thanks for your input.

Best wishes Graham


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