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Pontifications on Poison

Being some ramblings on events associated with poisonous plants.

Saturday 17th December 2011 

In the northern hemisphere, this seems like an unusual time of year to find a newspaper article about Heracleum mantegazzianum, giant hogweed, but a local paper in British Columbia, Canada, had an item that sent me frantically searching to see if one of its claims could be substantiated.

The article, in Pique Newsmagazine, is about efforts to encourage people to donate to the Community Foundation of Whistler a body that is making grants to the Sea to Sky Invasive Species Council (SSISC) to assist it in dealing with 65 invasive species in the area.

Heracleum mantegazzianum, giant hogweed,

Heracleum mantegazzianum, giant hogweed

It says that the two most serious of these invasive weeds are Heracleum mantegazzianum, giant hogweed, and Fallopia japonica, Japanese knotweed. Then comes the sentence that intrigued me;

In Europe, tens of thousands of people are treated every year for hogweed burns.

That sent me off searching to see if I could find any figure like that. It proved to be difficult. There’s no central register giving details of every case so you can’t just look up a chart and find figures. In fact, I found it impossible to find any published statistics from any source.

I went back to the WHO’s ‘International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10)’ that I mentioned, yesterday, and tried to find what classification would be used for hogweed burns. The problem seems to be that burns are classified more by their effect than by their cause so I don’t think a hospital would have a way of recording a burn as being due to giant hogweed.

There’s an added problem that there is a classification for ‘poisoning by topical agents’ so, I suppose, you might think that defined the action of giant hogweed on the skin.

In all, I don’t think there is a way to reliably collect data on the extent of giant hogweed injuries so it makes it hard to justify the claim that it is ‘tens of thousands’ of cases every year.

But if it is difficult to prove that there are so many then is it possible to disprove? Or, at the very least, cast substantial doubt on the figure.

I think it is, if only because of the way incidents are reported in the media. For example, the Sun, in 2009, reported on the case of a nurse who suffered severe burns to her arms and legs after getting splashed by the sap when cutting down a 4m high plant in her own garden. And, in 2010, the Times reported that a young boy required skin grafts after suffering burns from contact with Heracleum mantegazzianum.

For 2011, Google News only shows ten stories about giant hogweed none of which deals with an actual case.

It seems to me that, if there were ‘tens of thousands’ of cases every year, they would be more widely reported and, I also think, if a single incident is deemed worthy of coverage by a national newspaper then there can’t be that many of them.

It looks like another example of lazy reporting and you are, possibly, right if you are thinking it is not so serious. But, to me, it is another illustration of the way a false claim about the effects of a poisonous plant can find its way into the public domain so that, in the end, it becomes something that ‘everybody knows’.

Giant hogweed can be an extremely unpleasant plant to have contact with but the way to spread the knowledge that will prevent people having that contact is not by massively over-stating the extent of the problem.