I am concerned about the continued use of plastic labels in our vegetable gardens made from polypropylene. These "micro plastics accumulate in the root zone and can be found in fruits and vegetables" see Isabelle Gerretsen. BBC "How microplastics are infiltrating the Food you Eat"
Anyone else concerned?

Interesting thought. I don't use markers though, but I imagine there are other means we might be exposing ourselves (plastic garden stakes come to mind and I think osmocote uses resins in their slow release fertilizer).

Yes plastic garden stakes would also not be acceptable. Osmocote adds to the list, it appears

Get a bunch of the wooden popsicle sticks and write on one end that's not in the soil? They probably make wider ones for crafts to make it easier.

Uncoatef wood seems like a good choice.

They do make "food safe" popsicle sticks (like, I wouldn't use ones from a craft store).