Can you use pressure treated lumber for raised garden beds?
The short answer is NO.
Pressure treated lumber has toxic chemicals in it.
CCA or Chromated Copper Arsenate was used until the EPA ruled against its use in 2003. CCA was replaced by copper-based pesticides/preservatives. The new copper-based pesticides/preservatives are ACQ or Alkaline Copper Quaternary, CA-B and CA-C better known as Copper Azole and Copper Naphthenate.
You don’t want any of these lumber preservatives near things that you are going to eat. There are many chemicals in these solutions and they are toxic to insects and fungus. I certainly don’t want any traces of these in my food.