Final answer:
The amount of poppy seed bagels needed to test positive for opiates varies, with some cases showing a positive result after one heavily seeded bagel, though more commonly after several. Modern drug tests typically require significant consumption to yield a positive result due to higher screening thresholds.
Step-by-step explanation:
The question of how many poppy seed bagels would need to be consumed to obtain a positive screen for opiates does not have a definitive answer because it depends on a variety of factors such as the amount of poppy seeds on the bagel and the sensitivity of the opiate test. However, research has shown that consuming poppy seeds can lead to a positive result for opiates because the seeds can contain traces of morphine and codeine, substances that are tested for in drug screenings. While there is no precise number, case studies suggest that it is possible to test positive after consuming just one bagel with a heavy amount of poppy seeds, though it's more commonly noted after eating several bagels.
Screening thresholds vary, but most modern drug tests are calibrated to levels that would require significant, often unrealistically high, consumption of poppy seeds to yield a positive result. This adjustment in thresholds helps to prevent false positives due to dietary habits. However, if a test has a very low threshold, consumption of even a smaller number of bagels, such as 2 or 3, could potentially lead to a positive result if the poppy seeds are unprocessed and contain higher opiate levels.