At the confirmation level would they be able to tell the difference between poppyseed ingestion and opiate abuse?
They could not. Poppy seeds are a direct product of the opium poppy, Papaver somniferum
. Not a cross-reaction or false positive
. The positive result derives from the actual presence of morphine. The only contraindicator would be in quantitation of the morphine. Opiate abuse would lead to greater amounts of the analyte v. the relative low levels present from ingestion of food. That of course requires expert interpretation of the test. Too often absent. It's lucky that you advised someone of your concerns. If I were you I would make a written notation of that action including the individual's name and time of occurrence.
The foregoing assumes the worst case scenario. While poppy seeds can
result in a positive it is more likely that such will not occur. But it is always advisable to be prepared.
What should occur, in the event of a confirmed positive, is that a Medical Review Officer (MRO) would contact you prior to the reportation. At that point you could explain the circumstances and hopefully the positive would be reclassified by the MRO and reported as negative.