The research is clear here. Modern CCA treatments (the only one with arsenic) require preservatives to be applied first which prevent leaching of arsenic. There has never been a study that I can find which shows a genuine risk of arsenic toxicity from eating from a treated garden bed where crops are planted at least a few cm from the edge of the bed.

And if that's not enough, choose one of the many other treatment options, or line your bed with a proven-safe polythene liner, or use untreated timbers that are resistant to rot like cedar/macrocarpa. If you have any real research to show that any of these options are unsafe I would love to read it.