Evidence shows toxicity in birches

Last updated 11:00 21/01/2014
Tom Tothill
DAVID ALEXANDER

TREES NEVER SUSPECTED: Tom Tothill with silver birches near his Christchurch home.

Elspeth Tothill
Supplied
ALLERGIC: The late Elspeth Tothill.

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OPINION: In 2007, Elspeth (Jimmo) Tothill died after suffering an allergic reaction linked to silver birch trees near her home. TOM TOTHILL writes that despite his wife's death, officials have opposed his requests to remove the trees.

There is empirical evidence which points to toxicity from pollen and vapour given off by the common silver birch tree, Betula pendula. Pollen is the major form of toxicity given off in the spring when the tree is in flower. Following flowering the tree drops all the petals from the flowers causing a mess. Then they produce the catkins which fall from the tree, making another mess.

After the tree gets its spring leaves, herbivorous insects are attracted, which suck sap from the leaves and give off a scented vapour. If you happened to park your car under a tree, this vapour falls on the car, covering it with a sticky dew.

This is called methyl salicylate. It is a highly toxic substance. It is a cause of irritation of the lungs manifesting itself in a chronic cough. This vapour surrounds the trees until the tree sheds its leaves. So it isn't just pollen that effects people, it is this vapour that carries on making people feel ill. These organisms can enter the body and lie dormant in the body awaiting a moment when the person eats an apple or other fruit or nuts when it can suddenly trigger an anaphylactic event, causing almost instant death unless help is at hand.

Additionally, there have been reported cases where pregnant women have been exposed to Betula pendula and babies affected in utero.

The Betula pendula produces millions of seeds from each tree every year. Every seed will germinate and they are easy to grow. They grow very quickly so became a favourite many years ago, much to our ignorance, and now sorrow.

From January until May the tree sheds its seeds which get into everything. Every time there is a strong wind the tree sheds small branches everywhere. Methyl salicylate is oil of wintergreen used for cleaning grease and grime from engines etc. It is an ingredient for linament, so should never be ingested.

So both the pollen and the vapour from silver birch trees can affect people throughout the season who have a propensity to respiratory allergies and cause them much distress, as in the case of my wife whose death was attributed to hypersensitivity pneumonitis causing fibrosis of the lungs. All the early part of her life in the country, she suffered from hay fever caused by grass pollen. When eventually we moved to town she had very little hay fever and became much better.

Then, in 2003, we moved to our present home, where there were 12 silver birch trees within 50 metres of our house, and she started to develop respiratory problems.

We never suspected it was exposure to these trees causing the problem.

We now have 10 trees within 50 metres of the house. We negotiated with our neighbour to have two removed that were overhanging our property and house. My present wife has started to suffer sneezing eye irritation and runny nose. I have never had the slightest effect from antibiotics or from an allergy in my life, but am beginning to suffer coughing and shortness of breath, necessitating medical investigation, sore eyes, runny nose and lethargy.

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City arborists are renowned to be implacable opponents of the removal of Betula pendula silver birch trees whether in Christchurch or elsewhere. They declare their fondness for silver birch trees. However, they are not permitted to approve subdivisions today that show planting applications which include pendula silver birch, knowing the toxic nature of the species.

I have made several submissions to the arborist asking if I could pay for the removal of the silver birch trees in a park near my property, and replace them with a suitable tree of the council's choice at my expense. But they have refused the offer, stating that I would create a precedent.

What now that a precedent has been set (by Rugby St resident Hamish Riach's successful application to have two trees replaced at his expense)? Do they want blood on their hands if we should die from some related condition due to our exposure to these toxic trees?

In the north of the northern hemisphere there are silver birch trees everywhere but they are not our common pendula variety.

In some places, pendula are not permitted within 2km of residential areas because of their known toxicity.

There are some 50 silver birch trees in Rugby St.

They are Betula pendula. There was one silver birch outside 65 Rugby St which was Betula utilis. Betula utilis is different from Betula pendula, as it has oval leaves which are plain rather than serrated and has a more erect habit.

It is a more beautiful tree than the pendula. It is not invasive on human health and does not appear to have allergenic effects on humans with allergies.

So, plant the Betula utilis and you will enjoy a lovely silver birch tree.

- The Press

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