VOY Season One Edit
There is a mention of thoron in Voyager's first season. – The preceding unsigned comment was added by 188.8.131.52 (talk).
Removed Real World Info Edit
220Rn, having a half-life of 54.5 seconds and produced by the decomposition of thorium.
Removed as I don't believe any of this is stated in canon.--Cleanse ( talk ) 10:26, October 21, 2017 (UTC)