I would not use pressure treated lumber for a tortoise enclosure. Although the arsenic based treatment was discontinued pretty universally in 2003, it is still a copper azole product used most commonly today. It does leach chemicals and will do so for years. It is rated to be effective in the wood for up to 20 years, and to be effective, there must still be active ingredients. It is always cautioned against using anywhere near food prep areas. Since my tortoises will bite at lots of things growing next to the edges of the enclosure, I would not want to take a risk at all with mine.