Can elves die by being poisined???

[Telchar]

Beside the obvious Eöl/Aredhel case here are some other references that might help you guys...

In 2509 Celebrían wife of Elrond was journeying to Lórien when she was waylaid in the Redhorn Pass, and her escort being scattered by the sudden assault of the Orcs, she was seized and carried off. She was pursued and rescued by Elladan and Elrohir, but not before she had suffered torment and had received a poisoned wound. She was brought back to Imladris, and though healed in body by Elrond, lost all delight in Middle-earth, and the next year went to the Havens and passed over Sea.

They sought long for her in vain, fearing that she had been ensnared, or had drunk from the poisoned streams of that land; but the fell creatures of Ungoliant that dwelt in the ravines were aroused and pursued them, and they hardly escaped with their lives.