[dattashri]

It is almost compulsory to use wood preservative treatments. Without treatment, the wood cannot last longer. This wood starts degradation and decomposition with the contacts and reactions of external environments such as moisture, weathering, biotic organisms such as fungi and insects. Since the resources are limiting, only the preservative treated wood can provide service for longer periods with intended quality without any maintenance and replacement, therefore the treatment should made compulsory for exterior uses such as poles, post, beams, roof shingles, park furniture and so on.
Even the less durable species can be utilized with the preservatives treatment for longer periods. Therefore, the wood treatment should be encouraged and promoted.
Selection of the right preservative and treatment methods depends on the objectives, budgets, availability and specific use requirements of work place and it is quite an important decision regarding the wood preservative.
Handling of preservatives should be wisely managed so that it could not be hazardous to people and society. Treated wood should not be used where it may come into direct or indirect contact with public drinking water.
Treated wood should not be used under circumstances where the preservative may come in contact with food or animal feed, like food containers. It can be hazardous to health

 

[MrBeam]

your right!

 

[newmexico]

Linseed Oil...maybe make up a soup of both linseed oil and pine tar. The Vikings made up such a "Soup" for sealing wood ships.

 

[VA Wood]

There is another alternative to chemically treating wood for outdoor use. I believe the process was originally developed in Scandinavia (Sweden, Norway, Denmark, Finland).
Essentially, they "cook" the wood (many different species are done this way) in a "treatment "oven" where they monitor the temperature and humidity. The temp is varied according to a calculation done - based upon the wood's species, dimensions and moisture content. This "cooking" renders the cellulose (food for termites, ants, and mold/mildew) "inert"(?) - thus no longer subject to "attack" by these living organisms.
This process leaves the wood "chemical-free" - which seems to be the thrust of your post.