bleach cleaning on chopping board.... dangerous?
The ever lovely cleanipedia actually reccomend using chlorine bleach solution to sanitise chopping boards

https://www.cleanipedia.com/gb/kitchen-cleaning/kitchen-cleaning-how-to-clean-your-chopping-boards 

The comments under the question also offer some very good advice.

My personal thoughts are that it should be perfectly safe. When on survival training we used bleach to purify water to drink (in small quantities!) 

I would suggest that you could now wash the boards in plain boiling water just to ensure no residue remains.