Multiple realities
(covers information from several alternate timelines)
A trace element was an element needed by a lifeform to maintain a proper physiology.
According to a diagnostic analysis run by Doctor Beverly Crusher in 2364, excess or deficiency of trace elements could have a negative impact on chromosomes. (TNG: "When The Bough Breaks")
When the Krenim weapon ship erased the Garenor homeworld from history, Annorax asked for the trace elements. Obrist reported they were diminishing. (VOY: "Year of Hell")