information - Scottish Natural Heritage

Items such as picnic table tops, children's play equipment, containers for Page 18
foodstuffs such as potatoes, and surfaces which may be in prolonged contact
with animals, require special consideration. The only wood preservatives
which should be considered are the CCA types. These preservatives are free
of taint or odour and have a satisfactory record of use in these areas. Before
being used for these purposes, the treated timber should be left for at least
seven days followed by hosing down and light scrubbing to remove any loose
surface deposit. Low levels of arsenic occur naturally in our everyday
environment and although not to be encouraged, the ingestion of small wood
particles treated with this form of preservative is unlikely to be of serious
consequence. Where surface coatings are used in these sensitive areas, the
manufacturer should provide an assurance of their suitability.
Where preservatives may come into close contact with valuable plants, the
waterborne CCA preservatives will generally present no problems when
treated as above, but creosote, pentachlorophenol in heavy oil, and some of
the organic solvent based preservatives may be damaging. Organic solvent
preservatives are made in special horticultural grades, usually bright green in
colour, and providing the preservative is allowed to thoroughly dry after
application, they are harmless to most plants.