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Pontifications on Poison

Being some ramblings on events associated with poisonous plants.

Saturday 18th February 2012

I’m famous. Well, not really, but there are a number of people who may have read about me if they didn’t have anything better to do before Christmas.

Some months ago, I was contacted by a freelance journalist who said she was writing a piece about using plants as murder weapons and would I mind answering some questions. She said the piece would appear in ‘The Field’, she hoped, but couldn’t say when.

I’d completely forgotten about it until the secretary of the group I spoke to a couple of weeks ago said she’d been reading about me. Finally, after a bit of digging and shelling out for the back number (The Field doesn’t seem to put all its content online), I’ve got the article in front of me.

It’s quite flattering. I’m mentioned in the first paragraph and there’s a separate box looking at five plants that have ‘form’ when it comes to murder that credits me with the information. It also quotes what I always say when asked about homicidal plants; if I had murder in mind I’d use a metal not a plant. It’s that difference, which turns out not to be completely clear cut, that I want to write about today. Before moving on to that, I did just want to say a thank you to Jennifer Hirsch, the journalist concerned, for writing about Georgi Markov without any mention of an umbrella. That must be a first.

In the way that people get confused about information, I’ve been told by various people that such and such a plant contains arsenic. Now, although you’d never make a motor car out of it, arsenic is, chemically, a metal so it is not a plant poison. It can, however, be absorbed by some plants and this open access paper is about the arsenic content of organic brown rice syrup.

There’s a danger of getting into linguistic knots from here. I don’t know who decided that plants grown without pesticides or chemical fertilisers should be called ‘organic’ but it does create difficulties.

To a chemist all substances are either organic or inorganic compounds. Organic compounds contain carbon; inorganic compounds do not. All plants contain carbon so, to a chemist, all plants are organic though they can contain inorganic compounds. But when you are talking about how plants are grown, you have organic and non-organic. Note the different opposites and, just to add to the fun, note that a plant can’t be both opposites. That is a non-organic plant is not inorganic.

The reason we’re talking about organic brown rice syrup rather than just brown rice syrup is that the product is used to sweeten prepared foods and is favoured by those who object to the use of high fructose corn syrup because of fears about its tendency to cause obesity and the processing it goes through. For those people, brown rice syrup is an alternative and, just to cover all the ethical bases, this is primarily produced from organically grown rice.

Rice is a plant that can absorb arsenic so the authors of the paper wanted to see what the arsenic content of rice syrup and the products made with it was. The complication with language comes because arsenic forms both organic and inorganic compounds in plants. Inorganic arsenic is known to be taken up by the body more easily that organic arsenic so the researchers also wanted to know how much of the arsenic in organic brown rice syrup was organic arsenic and how much was inorganic.

The research looked at a number of food products and found that the levels of arsenic in some, when calculated as the equivalent to concentration in water, exceeded US standards for drinking water. They also found that the arsenic was mostly in the inorganic form and, thus, more susceptible to absorption in the body. Of particular concern, was that the authors found two brands of infant milk formula and one soya milk infant formula with quite high arsenic levels.

The paper concludes that the absence of any limits on the arsenic content of foodstuffs is a cause for concern and the authors call for urgent action to introduce limits and a regime for enforcing them. Because the authors looked at organic brown rice syrup, I foresee there being the chance that supporters of organic food production will dismiss this work as another attack on their beliefs from the mainstream so it’s worth repeating that, it seems, the authors looked at organic brown rice syrup because that is what is used as the alternative to corn syrup.

Though the levels found are of concern in respect of long-term harm rather than being at a level that would cause poisoning from a single meal, it seems that, theoretically at least, I’m wrong to separate metal poisoning from plant poisoning.