Timber contains nature oils and resins, with a range of volatile chemicals, some hazardous and some not. The types of chemicals given off depend on the particular type of wood. The amount given off depends on the number of storage glands exposed to the air i.e. on the surface area. For example, fresh pine shavings have a much stronger smell than a freshly sawn shelf of pine. It also depends on the age of the wood as the storage of volatile materials is depleted over time.
Pine is one of the less hazardous timbers and fresh pine shavings are often used in pet shops with puppies and kittens. However, all forms of saw dust are considered to be potentially cancer causing and should not be breathed in. So work outside if sawing wood or wear an effective mask.
“Treated pine” refers to pine that has been treated with chemicals so that it can be used outdoors. It can be used as retaining logs for landscaping, cubbies and free-standing pergolas and decking. The original chemical was copper chrome arsenate (CCA). Copper provides protection against fungal rot, arsenic against termites and other boring insects and the chromium hold these two chemicals together. Whilst not really proven, there were concerns about the arsenic possibly leaching into the ground, such as in vegie patches and from landfill sites (tips) into ground water. The only proven issue is that the arsenic becomes airborne if the wood is burned. Nowadays there are three or four more environmentally friendly alternative treatments.
Any wood you use in constructing a cage needs to be coated so that it is waterproof. This prevents liquid waste seeping the wood and allowing rot. It also allows you to use water-based cleaning agents when you need to so. A seal that keeps water out will also keep any volatile chemicals in. So you can use whatever wood you like. If you want to go with a natural wood grain, three or so coats of polyurethane will do the trick. This is what high quality timber floors are finished with to make them water and wear resistant. Two or three coats of acrylic paint will have the same effect. Too easy.
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