Impregnated timber and wood products
Impregnated timber is
treated with chemicals to prevent it from rotting. Most impregnated
timber today is treated either with creosote or with heavy metal
salts.
Timber that has been
creosoted is blackish-brown, smells of tar and contains a variety of
chemicals, some of which are carcinogenic. Old railway sleepers and
telephone poles are often creosoted. They must only be used where
they will not come into contact with skin.
Timber is often
pressure-treated with salts of various heavy metals. A combination
of copper, chromium and arsenic salts, or CCA preservative, is most
commonly used. Arsenic compounds are the most dangerous of these.
The toxic chemicals in
impregnated timber gradually leach into the surroundings. This is
why you should not use impregnated timber around vegetable plots or
where you store food.
What can you do?
From October 2002 the use of timber
impregnated with chromium and arsenic compounds will be forbidden
for most purposes, including decking, weatherboarding and fencing.
A number of less harmful
products are therefore appearing on the market. Some types of
impregnated wooden materials do not contain heavy metals. Some types
of wood are also naturally more resistant to rot.
If timber does not come into
direct contact with the ground, you do not need to use impregnated
materials.
If the children’s sandpit is
made of impregnated timber, you should change the sand every other
year. Or even better, replace the planks. You can also reduce the
risk to health and the environment by staining or oiling impregnated
wood. This reduces leaching of heavy metals.
Waste
Impregnated wood must not be burnt in
ordinary stoves or on bonfires, because it produces toxic smoke and
very toxic ash. Any impregnated materials must be delivered to
approved waste treatment facilities where they can be dealt with
properly.
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