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Pontifications on Poison

Being some ramblings on events associated with poisonous plants.

Monday 24th February 2014

Time for tea. In my talks I use Camellia sinensis, tea, to illustrate issues about addiction, the use of words and the confusion of facts. Take the last of those. The answer to the question ‘Which has more caffeine, tea or coffee?’ is tea – and coffee. There is more caffeine in a kilo of dry tea than there is in the same weight of coffee beans but there is more in coffee than tea when it comes to a cup of prepared beverage. Er, generally. Depending on how dry the tea leaves are. Or, how strong the beverage is.

And the fact that people exhibit physical symptoms if they suddenly reduce or discontinue their consumption of caffeine-bearing drinks makes us ask whether addiction is as straightforward as it is generally represented to be. But it is the third issue – the use of words – that interests me today.

Tea is no longer just a beverage made by pouring boiling water over dried shredded leaves from the tea plant. It is also used for all manner of drinks made in a similar way but using other plants. I have no way of determining whether this arose because it was thought that terms like ‘infusion’ ‘tisane’ or ‘decoction’ were too esoteric for the buying public or whether the hope was to equate the known benefits of tea-drinking with beverages made from other plants.

Whichever, I think it has led to the problem of people assuming that anything called a ‘tea’ must be healthy and safe. I want to look at two very different sorts of ‘tea’ that show this is not the case.

I’ll start with something I’ve only just found out and still have unanswered questions about. The main alkaloid in Papaver somniferum, opium poppy, is morphine but the plant produces others including thebaine and codeine. What I didn’t know before was that morphine is produced from a chemical reaction in the plant that converts thebaine to codeine to morphine. In Tasmania, one of the largest growers of poppies for conversion to pharmaceuticals, a genetically modified variety of opium poppy is grown where this reaction is almost entirely eliminated. That means the product extracted from the plant is thebaine and this is the raw material that can be converted into a variety of different opioid medicines.

There is a problem with this production route; thebaine is very much more toxic than morphine. It sounds as though the modification was intended to boost the efficiency of production but I haven’t been able to dispel a concern that a secondary motive was to render the plants harmful to anyone wanting to steal them for illicit use.

If there were that secondary motive, it is probably effective for people in Tasmania who know what is being grown but, as this story shows, a foreign tourist should not be expected to have that knowledge.

You could use the story to spark many issues relating to the growing of potentially harmful plants but my interest, today, is the headline to the report;

 ‘Danish tourist dies after drinking toxic tea brewed with poppies in Oatlands, Tasmania’

It is that use of the word ‘tea’ and the indication that the association between ‘tea’ and ‘natural’ or ‘healthy’ shouldn’t always be made.

And that brings me to the second sort of ‘tea’. My Google alert for ‘ragwort’ took me to a page recommending the use of an extract made from the roots of a variety of ragwort, in this case Senecio aureus rather than Jacobaea vulgaris (syn. Senecio jacobaea), common ragwort, for use during labour and to relieve menstrual pains.

The author talks about the need to correctly identify the plant because it is similar to a number of plants where the roots are toxic but makes no mention of the fact that all members of the Senecio genus contain pyrrolizidine alkaloids (PAs) capable of causing liver damage. The recommended administration route is via a tincture but, of course, such tinctures can be the basis for making a ‘tea’ from the root.

Though rare, there have been cases when death has occurred following the drinking of teas made from some variety of Senecio.

The Canadian Poisonous Plants Information System (CPPIS) cites a case where a newborn baby died as result of its mother consuming Senecionine and says;

‘Humans should not ingest foods that contain any plant material from this genus.’

Now, I’ve frequently written about the over-statement of the risks from plant poisons and my usual cry is ‘show me the bodies’ so I’m aware that I could be making the same error by taking the CPPIS statement at face value but, in this case, though few in number, it is possible to show that deaths have arisen and, given that PAs can lead to cumulative liver damage even if individual doses are small, I believe it is irresponsible to recommend the use of this plant without giving any warnings about the risks from overdose or long-term use.

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