We have some radish that have these darker areas in the flesh. Currently, we are on the island of Malta where food ingredients are very low quality in general, so anything out of the ordinary immediately becomes suspicious :)
Click for larger size image.
It's a fungal infection. If you google Aphanomyces raphani you will see much more serious examples but that how it looks usually when the outside is not affected (so also not thrown out by seller)
I'd be tempted to say,
"I don't know."
In very many cases, 'I don't know' often goes hand in hand with '& I don't much care either...'
However, when it comes to fresh fruit & veg of dubious provenance that is going to be eaten raw, that rapidly turns into,
"I don't know so I'm going to play safe & throw it away."
The only mitigation - & I would still be wary of it - would be to take it back to the supplier & ask them. There's an outside chance they could say, "Ah, over here, they all look like that." ..though I'd still want more evidence.
