Yes, treated lumber is safe for building raised beds of edibles. Most wood now is \"pressure treated\" not soaked with creosote. Even railroad ties have been proven safe but just to be sure, I would not grow root crops like carrots right next to a railroad tie soaked in a creosote. Plant at least six inches away. You don't have to take this precaution if you use pressure treated wood. Keep growing, Marianne Binetti