Acetyl groups, which are simply comprised of oxygen, hydrogen and carbon, are already naturally present in all wood – as well as in humans and other mammals. This means that the manufacturing process adds nothing to the wood that does not already naturally occur within it. The end product, Accoya® wood, does not add toxins to the environment. Incidentally, the only by-products from the manufacture of acetic anhydride are a small amount of valuable fertilizer and trace amounts of acetic acid, which can be biodegraded.
The effect of altering the wood’s chemical structure, as opposed to merely altering its chemical content, is essentially to create a new product which is pure, natural and more durable. By contrast, virtually all other treatments merely insert chemicals (such as oils, ammonia or metal compounds) into the cell walls of the wood.