Ineffective Quality Control Measures Could Affect Electronic Cigarette E-Liquids’ Secondhand Aerosol Emissions

SARAH FRESQUEZ, Daniel Walker, Talia Chavis, Sinan Sousan, Department of Public Health, East Carolina University

     Abstract Number: 46
     Working Group: Health-Related Aerosols

Abstract
Electronic cigarette (ECIG) e-liquids offer varying nicotine concentrations and ratios of propylene glycol (PG) to vegetable glycerin (VG). Increasing VG content can enhance the visibility of puff “clouds,” which correlates with increased PM_2.5, particulate matter 2.5 μm or smaller, mass concentrations, known to be associated with increased morbidity and mortality. E-liquids with different PG/VG ratios are widely available through third-party websites that may lack proper quality control. While users expect products to reflect their labeled contents, discrepancies in nicotine, PG, and VG levels can lead to unexpected PM_2.5 emissions. This study conducted chemical analyses of third-party e-liquids and measured secondhand PM_2.5 mass concentrations in a controlled chamber during 30-minute sessions. Experiments were performed using combinations of four freebase nicotine concentrations and five PG/VG ratios. The actual chemical values were compared to manufacturer-labeled values, revealing inconsistencies. For example, products labeled as containing 0.0 mg/mL nicotine were found to have up to 0.4 mg/mL. Those labeled 9.0 mg/mL ranged from 6.6–9.7 mg/mL; 18.0 mg/mL ranged from 13.6–25.7 mg/mL; and 48.0 mg/mL ranged from 34.7–44.7 mg/mL. Only 5 of 20 e-liquid combinations had VG levels within ±5% of their labeled values. The most extreme discrepancy showed a measured 19 PG / 81 VG ratio versus a labeled 80 PG / 20 VG. Measured PM_2.5 mass concentrations reached up to 72,049 µg/m³. Based on actual chemical analysis, higher VG content consistently resulted in increased PM_2.5 mass concentrations. These findings highlight quality control issues in commercially available e-liquids and demonstrate the public health risks associated with high secondhand PM_2.5 emissions. Stricter regulation and more accurate labeling of ECIG products are critical to protecting users and those exposed to secondhand aerosol.