Exploring the “poppy seed defense” in oral fluid: detection of opioids following poppy seed consumption

Abstract The “poppy seed defense”—a claim that a positive opioid test result is due to ingestion of poppy seeds—is occasionally encountered in forensic toxicology. The matter has been thoroughly investigated in urine but is less researched in oral fluid. We therefore aimed to perform an experimental study to explore whether consumption of commercially available poppy seeds would lead to detection of opioids in oral fluid. Additionally, we aimed to relate our findings to routine cases. Ten volunteers consumed either five crispbreads containing a small amount of poppy seeds, or 30 g of raw poppy seeds with a low opioid content (3.0 mg/kg morphine and 0.9 mg/kg codeine). Oral fluid samples were collected 0.5 and 2 hours after consumption. Additionally, a urine sample was collected 2 hours after consumption. Following ingestion of raw seeds, morphine was detected (estimated neat oral fluid concentrations 1.4–5.6 ng/mL) in all oral fluid samples 0.5 hours after consumption and in one (2.4 ng/mL) of five oral fluid samples after 2 hours. Codeine was detected (0.8–1.1 ng/mL) in three of five oral fluid samples 0.5 hours after consumption, but in none after 2 hours. Following ingestion of crispbreads, morphine or codeine was not detected in oral fluid, but opioids/-glucuronides were detected in three of five urine samples. When comparing our results with routine cases, we found that 14% of routine cases had morphine concentrations in oral fluid samples lower or similar to those seen after ingestion of raw seeds in our experimental study. In conclusion, we found that consumption of raw seeds led to detection of opioids in oral fluid, but the detection window appeared to be short. Comparison with routine cases indicated that the poppy seed defense may be a challenge when interpreting oral fluid results, particularly when low cut-off levels are applied.