In the Netherlands and Belgium a load-bearing structure made of treated wood is often used in a ventilated façade system.
However, the substances that are pressed into the wood are usually very toxic. Although there is sufficient supervision (certification) of the safety of employees in the production of treated wood, there is strangely enough no (or only very limited) control in the use (sawing) and waste phase of treated wood. This is despite the fact that, according to the European directive, impregnated wood in connection with the carcinogenic substances may not come into contact with human skin!
Copper II oxide and chromium trioxide (chromium VI) are often used in the preservation process. Chromium VI is extremely toxic to humans and is internationally known as a class 1 carcinogen. Used substances as tebuconazole and copper (II) carbonate-copper (II) hydroxide are not known as a carcinogen in Europe but in the USA known as a class 2B carcinogen.
This is why the use of treated wood is not permitted or unacceptable in many countries outside the Benelux. The use of treated wood of any kind is highly questionable because structurally very toxic, corrosive, environmentally hazardous and carcinogenic substances are used.
Finally, the one thing you must be extremely careful to never do with treated wood is burn it. Burning treated wood created toxic smoke that can be hazardous to health, so it is advised that treated wood be disposed of through normal waste collection services, unless it is a large amount of timber (where you will have to make arrangements with your council for it’s safe disposal).