Using Concrete Blocks for a raised bed - unsafe?

I agree with Nigel. There is very little chance of any toxins coming from concrete blocks and affecting your crops. People use all sorts of things to separate, hold back or form a boundary. Railway sleepers are used quite often and they are also chemically treated. Seepage is almost non-existent and will go downwards and also be diluted each time it rains or you water the beds. So for raised beds there's almost no possible problem.

I've used concrete blocks for edging for over 50 years. The crops nearby don't seem to have been affected but they are planted in soil that has fresh compost dug in each year (except the rhubarb patch which has a concrete block path on one side and the patch has been there quite happily for 65 years).

There are, obviously, things that can affect crops adversely but you would never grow anything if you worried about very minor forms of possible pollution. I'm more concerned about chemicals that are used on plants and, so, my garden is totally organic. Technically that may not be quite true because the bamboo canes that I grow my beans up are commercially grown and the bamboo has been chemically treated. The bamboo is put through a chemical bath before being transported. Just as a comment on my last sentence:- 'organic' bananas are not strictly organic. Although they are not fed with organic chemicals they are allowed to be called organic although almost all banana plantations nowadays put plastic bags over the bunches of bananas whilst on the plant and are allowed to put a gas inside to deter insects (it doesn't keep the snakes out ). They also, all, put the bunches through a very mild chemical (similar to bleach) bath as they can't export them unless they do so.

 

I just wash mine and I have no trouble