IPE doesn't show up on quite a few of the more popular toxicity charts
(DAGS wood + toxicity), but some list it as a mild irritant and
allergen--meaning that it can potentially affect a few (probably small
%) of the population.
Your question is tougher and no testing has been done that I know of,
esp. w/ reference to that one specific plant.
Note that some IPE intended for decking may be treated; if so, I would
not use it as mulch for any digestibles.
Sorry can't be of more help,