Thursday, November 25, 2010

Cyanide in the Garden - Mind Your Children!!

When Plot 34's self appointed head of secret tunnels was two or three years old, I had just started growing food. In an early effort to teach him about where his food came from, I'd pick off a lettuce leaf, take a bite and then pass it to him to taste it. Then I'd pick a bright red tomato and we'd share it. Natural enough and a good thing you might think?

The next day I caught him in the front garden trying to feed a poisonous white berry to one of his little friends.

Teaching very young children about food growing seems the natural thing to do but I'd forgetten that my little lad didn't know the difference between a big green lettuce leaf, a dock leaf or a rhubarb leaf. Or the difference between picking and eating a tomato or rowan berry. All he saw was his daddy picking leaves and berries off plants and then eating them. The message I'd given him was: "Picking and eating things off plants (all plants) is a new and interesting thing to do."

A three year old is surrounded by poisonous plants which we adults regard as innocuous. And if you show him how to eat leaves and berries off food plants, he's won't stop at the safe ones.

Most childhood poisonings occur under the age of 5, the peak age for poisoning is 2 years, and boys are more likely to be poisoned than girls - presumably because they're far more curious. I can remember my brother and I as children snacking down on some red berries from a tree in our own back garden which luckily weren't highly toxic but enough to make us pretty sick for a few days.

Last year I myself unwittingly poisoned my family with my own home grown potatoes. I'd starting storing them outside in a see-through plastic container where the sunlight turned them green, stimulating them to generate a poison called solanine. Viable tubers exposed to sunlight do this to protect themselves from being eaten by birds and animals.

Green potatoes, contain hugely high levels of solanine which, because children are smaller and lighter, will prove far more dangerous to them. The most famous case of solanine poisoning occurred in Britain in the 1970's where thirty schoolboys were hospitalised after the cook in the school kitchen used a sack of green potatoes. Green tomatoes also contain solanine to similarly protect themselves from predation before they're ripe and the leaves of both potato and tomato plants are also rich in the toxin.

Don't eat the greenies!

Early on in my food growing I simply didn't know that green potatoes are dangerous. It doesn't say so on bags of shop bought potatoes and no one ever told me. A straw poll of my friends showed that around half didn't know the dangers while the other half did and assumed everyone knew not to eat them.

Rhubarb leaves, while looking to a child vaguely like spinach or salad are also highly toxic - containing high levels of oxalates. During World War I rhubarb leaves were misguidedly recommended as a substitute for other veggies that became scarce leading to acute poisoning and deaths.

It might be a shock to learn that you can also find cyanide in your garden.

Many fruit seeds, particuarly those from apples and cherries, contain amygdalin, which when introduced to the human digestion system, degrades into hydrogen cyanide. The seeds need to be broken to release the poison and will otherwise pass through the digestion system sealed and intact. It is estimated that it would take a half cup of broken apple seeds to make someone seriously ill.

You might think: How the hell how would I consume broken apple seeds in quantity? Try running a bag of uncored apples through your blender. Again, if someone didn't know this about apple seed toxins, a poisoning could conceivably occur.

Comsuming uncored and blended apples will lead to small amounts of cyanide released in your system

Indeed plenty of items among our every day food products have, at one time, been poisonous. Anyone who's eaten tapioca pudding might not be aware that the roots of the cassava plant from which tapioca is made, contain hugely lethal levels of cyanide.

In Africa, the tribes who rely on it for food, have learned to crush the root and then rinse it out in wicker seives placed in fast flowing rivers and streams to strain out the cyanide. The tapioca we buy in the shops has the cyanide removed in commercial preparation.

And let's not forget the unnatural poisons we ourselves introduce to in the vegetable garden. One commercial carrot grower recently told me: "There are chemicals out there, commonly available in the shops and used in domestic vegetable gardens which should never, ever, be used without proper procedure and protection. When commercial growers use them we are obliged by law to use gloves, facemasks and so on, but we see people all the time spraying these substances liberally around them with no protection whatsoever."

That's where I got another fright. My Dad gave me Roundup, a strong weedkiller, for careful application to dock plants which just wouldn't go away. I normally avoid chemicals but this limited one off usage seemed justified to get rid of the docks once and for all. He'd poured a small amount of it into a plastic mineral bottle and being cautious with these things, he'd also stuck on a very large warning label clearly denoting it as a dangerous weedkiller. 

But as I said, younger children can't read. I'd stashed it on the allotment (I thought safely) behind my neighbour's compost bin. A few weeks later my young son (too young to read) walked up to me with it in his hands asking if he could have some "lemonade." Luckily he'd asked.

A quick glance around on my allotment quickly revealed chemical containers on neighbour's allotments. Those holders who don't have children on their allotments seldom think of the dangers to other people's young ones. Rats are common on allotments, as too is rat poison. The blue pellets are colour coded to ward off birds and so on, but to children they look just like sweeties.

Finally for those who grow in built up city areas, lead in the soil is something most people seldom consider. Lead is a poison which has got into the ground via decades of leaded petrol use. It occurs in highest levels in older central areas near busy roads and close to buildings which have had years of lead based paint used on them. The flakes fall off and land on the ground where they become absorbed into the soil and tend to stay there.

Most plants don't absorb lead, but some leafy plants, like lettuce and salads which are more popular in smaller city gardens, soak it up. For those living in much older houses, in areas of heavy traffic, it might be advisable to replace your soil, particularly the soil closest to older buildings, as testing for lead is expensive.

Peeling lead paint from old buildings can contaminate the soil in city areas

Most of the poisons mentioned above won't kill you but they might give you or your children a dose to remember.

Growing your own food is still the best way to provide your little uns with the most nutritious and pure food they can eat, but until they're old enough to know what's what, do cast a child's eye over your garden exactly as you would inside your house. Deploy the veg gardener's equivalent of keeping kettle flexes out of reach and electric sockets covered and when they're with you on the allotment or in the garden, always keep one eye out.


  1. Hi Mark,

    Love the book and lots of useful info. I would however argue with you over the apple seed and cyanide points you made. I read that the cyanide is in a form that is not poisonous to us, in fact these seeds contain Laetril that has been proven to fight against Cancer. A search on google for (apple seeds cancer krebs ) gives lots of interesting info. All the Best, Paul

  2. Thanks Paul for buying the book and for your enlightening comment. I didn't realise there were safe forms of cyanide!! I'll have to find out more about Laetril. Does that mean crushed apple seeds are actually useful and are they used in some way?