Selfsufficientish.com

Hi,
In my garden, there is a deck which is possibly treated with CCA (chromium, copper, arsenic), and a post in the ground that is treated with CCA. Also, before I knew about CCA, I put an off-cut from the deck amongst my pea plants for them to grow on.
I searched the internet, but I haven't found anything about how far you can plant edibles from arsenic-treated wood. Does anyone know how far?

Sesame

Not sure what the situation is in Aus, but in the UK we call that sort of treatment 'tanalising'. Strictly speaking, it is not quite the same, since the latest generation of tanalising chemicals (Tanalith-E) has cut out the arsenic and chromium. It still uses copper, but the other chemicals now used are reckoned to be biodegradable. Having said that, I doubt it should be used for 'organic' growing, but it might be worth checking whether you have CCA or Tanalith-E.

I have actually built my raised bed out of tanalised wood. In the short term, it's not something that worries me greatly, but I think this winter I will line the inside surfaces with some sort of impermeable membrane.

I suspect that the distance the chemicals will leach is partly dependent upon local conditions (how much rain you have, how water-logged the ground gets, etc.). Maybe you could set some sort of barrier into the ground to help contain any leaching.