It’s certainly not treated with anything by me, we’re very careful not to use any chemicals in the garden. It’s a bit off an old pallet or something I think, looks like pine or spruce. Almost all wood for outdoor use nowadays is pressure treated (unless you specifically buy untreated) during the manufacturing process so it no doubt will have chemicals in it as will the fences, sleepers and decking in our garden, no avoiding that unfortunately. None of it is treated with creosote, wood staining or anything like that though.
https://youtu.be/WEW44wZOdj0