First of all the the good news is that since the website sells to the aquarium hobbyist it is unlikely the wood is treated with insecticides.
That said, importing plant material (including aquatic plants, wood, leaves, etc) without the proper certificates and documentation is not responsible behavior. Some of the worst diseases and pests including Dutch Elm Disease, 1000 Cankers Disease, and Japanese Beetles that threaten our beautiful native forests all 'hitchhiked' to the US on plants and wood products. That is why our US Government requires inspections and certificates. If a shipment is improperly documented, and is caught by US Customs, the goods are confiscated and fines may be issued to the individuals that imported the items. It is the buyer / importer (you and me) that are required to know the laws and insure that shipments are properly documented.
I am not trying to scare you but I would encourage you to be responsible and not to order plants or plant material like wood or leaves from overseas in the future.
Last edited by Seattle_Aquarist; 02-26-2013 at 05:12 PM.