Crusher says "With tricyanate? That's hard to believe. It's slow to assimilate, difficult
to replicate, and hard to transport. There are a lot easier ways to poison a water supply. More effective ways too." So it's difficult, but not impossible, and probably exactly what Fajo did
to poison the water supply on on Beta Agni II, since it was all a lure to capture Data.
So now the only question is why Cardassian manifolds use beta-matrix compositors, and why they are "unreplicable". "Beta-matrix compositors" are a piece of technology, not an element or compound. I wonder why O'Brien didn't just replicate the materials and build
a new beta-matrix compositor.