Mischevious poppy seeds

I was watching an episode of MythBusters the other day where they tested an urban myth suggesting that eating baked goods with poppy seeds before a drug test would cause one to yield positive results for heroin use... and to my surprise it was true—eating a poppy seed bagel or two can actually make you yield false positives for up to three days.

I found a random article about this that I'll include here:

Opiates (morphine and codeine) can be detected in urine for at least 48 hours after one eats food containing poppy seeds. As little as a single bagel covered with poppy seeds could produce a false positive test for these drugs.

In 1990, a veteran St. Louis police officer was suspended for four months because his drug test showed positive for morphine after he'd eaten four poppy seed bagels the day before the urine sample was taken. He was reinstated with back pay after it was determined that poppy seeds and not drug use had produced those results. His case was especially puzzling to the department because the officer in question had a steady work record and demonstrated no indications of any problems before this incident was flagged during a random drug screen. The department performed an experiment by having another officer eat four poppy seed bagels and take a drug test. He, too, tested positive for morphine, confirming the poppy seed effect theory.

In 1999, a New Jersey prison guard was fired for the same reason: a poppy seed bagel he'd had produced a positive drug test. His case was subjected to further examination, and he was reinstated seven months later.

In 1997, a woman in Florida was awarded $859,000 in her lawsuit against Bankers Insurance Group because it had withdrawn a lucrative job offer to her on the basis of her poppy seed-influenced drug screen results.

In 1994, a Baltimore woman lost her chance for a job with an inner-city community health center because of her failed drug test, which was once again the result of the nefarious poppy seeds. In this case, the woman's fondness for lean corned beef and provolone on a poppy seed bagel cost her the job she wanted, because this prospective employer would not allow her a second urinalysis nor believe that her morning nosh had caused those suspicious test results.

Because of the possibility of poppy seeds' skewing drug test results, federal prison rules prohibit inmates from eating this ingestible. Moreover, inmates on furlough are enjoined from eating baked goods that incorporate poppy seeds because of the effect it has on their drug tests. (Without the poppy seed prohibition, anyone using opium derivatives recreationally could attribute his positive drug test results to a fondness for these seeds. The prohibition removes that possibility.)

1. Urban Legend Reference Pages: Poppy Seed Drug Test Results