When it comes to ceder and pine its actually the chemical released from within the sap. Hence is why pine and ceder shavings are bad but most still use pine ply or numbered lumber. I would avoid Ceder at all costs the aromatic fumes it puts off are just to much for most animals respiratory tracts but pine in the solid state is generally fine.
That being said any log or limb from a non-poisonous species of plant is fine. So yes IMO elm is fine unless someone knows something I don't.
Best of luck
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Jeremy
"I am become death, the destroyer of worlds" July 16, 1945 Robert Oppenheimer
1.1 Double Het "Sharp" Snow RTB's
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0.2 Pastel Hypo RTB's
2.0 Double Het Stripe Albino RTB's
0.1 Suriname RTB
0.1 Anerthrystic RTB
0.0.10 Red Bearded Dragons
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