ArticleThe International journal on drug policy2025
High variation in purity of consumer-level illicit fentanyl samples in Los Angeles, September 2023-April 2025.
Article in The International journal on drug policy, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 9 papers.
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Who cites it
9 citing papers in PubMed.
- Fentanyl purity and overdose decline: A reexamination of geographic trends.Science advances · 2026Article
- Charting the decline of the fourth wave: US overdose deaths by race, ethnicity and substance involvement.Addiction (Abingdon, England) · 2026Article
- Fentanyl Purity and Overdose Decline: A Reexamination of Geographic Trends.medRxiv : the preprint server for health sciences · 2026Article
- Estimating the Daily Milligrams of Morphine Equivalent of Illicit Fentanyl Use in Los Angeles: Clinical and Epidemiological Implications.medRxiv : the preprint server for health sciences · 2026Article
- Charting the Decline of the Fourth Wave: US Overdose Deaths by Race, Ethnicity, and Substance Involvement.medRxiv : the preprint server for health sciences · 2026Article
- Temporal and regional associations between fentanyl concentrations in the unregulated drug supply and drug-related mortality in British Columbia, Canada.The International journal on drug policy · 2026Article
- What does 'polysubstance' really mean? Comparing drug-involved deaths in CDC records vs. detailed medical examiner data from Los Angeles.The International journal on drug policy · 2026Article
- The Donovan Memorial Lecture: 'Fentanyl-Plus': A New Era of Fentanyl Polydrug Combinations in the North American Overdose Crisis.Journal of medical toxicology : official journal of the American College of Medical Toxicology · 2026Article
- Emerging Concern: Lidocaine Adulterated "Purple Fentanyl" in the Midwest.Kansas journal of medicineArticle
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Abstract
backgroundThe illicit manufacture of fentanyl results in product of unknown purity, contributing to overdose risk. However, data on the purity of illicitly manufactured fentanyl (IMF) in the United States typically comes from law enforcement sources and almost no information relevant to retail-level product is made available. We aim to quantify IMF purity among samples from a community-based drug checking program operating at four geographic sites in Los Angeles, California.
methodsDrug samples (n = 1763) were obtained from participants who also answered an anonymous survey about sample characteristics. Qualitative and quantitative analysis were conducted leveraging directly observed mass spectrometry (DART-MS) and liquid chromatography mass spectrometry (LC/MS) respectively. LC/MS quantified a panel of compounds including fentanyl and fluorofentanyl. Composite IMF purity was estimated by adding the percent mass of fentanyl and fluorofentanyl.
resultsA total of 353 samples had either fentanyl, fluorofentanyl, or both quantified between September 2023 and April 2025. Median IMF purity was 5.8 %, mean 10.0 %, SD 11.1 %, range 0.1-64.9 %. Samples expected to be fentanyl (n = 308) had higher median purity (7.0 %) compared to those expected to be heroin (n = 24, median purity 1.4 %) or other drugs (p < 0.001). Powder samples (n = 318) had higher median concentration (6.9 %) compared to pills (n = 11, 0.7 %) or tar (n = 22, 1.4 %) [p < 0.001]. Of expected-fentanyl samples, 42.5 % (n = 131) had an IMF purity of <5 %, while 17.5 % (n = 54) had purity over 20 %.
conclusionsWe found high variation in IMF purity among samples sold as fentanyl, even among samples obtained on the same day, in the same location. This volatility likely plays a role in high overdose risk, even among people with opioid tolerance, in the fentanyl era. Further research is needed to compare these findings to other locations across the United States.
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