tulip wood is WAY bad it is actually quite bad for woodworkers. oak is full of tannin that is a natural insecticide It is maybe ok I am not sure maple or birch are good where I am poplar is quite common and cheap but I don't know about other areas. Any wood treated with a polyurethane is basically plastic until the encapsulation coat is breached then is can out gas quite quickly. Just check it for blemishes each time you clean it and all is well.