Experimental bounds on microcausality violation

In “The Great Soviet Encyclopedia”, 3rd Edition from 1970-1979, (evidently an old book), some V. I. Grigor’ev has a well-written little note on microcausality. Towards the end he states an experimental bound on the vialotation of microcausality. According to that ancient encyclopedia article, if such violation occurs at all then it must be on scales smaller than $10^{-15} cm$.

I don’t see a citation for that number in his text (I don’t have the original book in my hand though, to be frank) and I am wondering which experiment Grigor’ev might have been thinking of.

And: if there are decent such experiments indeed, then probably there are more recent numbers on whatever that experiment actually measured.

My question is if anyone might be able to help me with finding whatever useful there might be to say about experimental bounds of the kind Grigor’ev seems to be referring to, or anything similar.

Maybe I should say that I am not trying to find such violations. Rather, I am in some discussion with some mathematicians interested in axiomatic QFT, and I’d find it entertaining to be able to accompany the statement of the microcausality axiom (or a similar axiom) with something substantial that has the word “experiment” in it.