No.
No, this is chickenshit, this is too important, this is Worldwound-grade stuff.
Start by informing all the Worldwound-signatory countries at the top level. Cheliax doesn't need to explain how it knows, it just needs to make it visible that it's immediately banned Element-82 coming into contact with human biology mortal biology, they don't know how it generalizes to races that don't interbreed with humans but there's no point in taking chances until they do.
Keltham sends a priority message to Lrilatha.