2020 No https://pubmed.ncbi.nlm.nih.gov/33712386/ Shamout, Mays North America Observational Exposure Study High School (9-12) Electroni nicotine delivery systems Nicotine Tobacco Adolescents Students School Curriculum Most of the collected JUUL pods (24/26 pods) had a nicotine concentration (43.3 mg/ml, 95% PI: 21.5–65.1) outside the prediction intervals (PI) of the 3% (33.5 mg/ml, 95% PI: 31.8–35.2) and 5% (55.0 mg/ml, 95% PI: 51.5–58.3) commercial JUUL pods. Most (73%) collected JUUL pods had VG concentrations (583.5 mg/ml, PI: 428.9–738.1) lower than the 3% (722.2 mg/ml, PI: 643.0–801.4) and 5% (710.5 mg/ml, PI: 653.1–767.8) commercial JUUL pods. Used JUUL products collected from high school students or found on school grounds were not chemically consistent with the manufacturer’s stated formulations.