Defense Date
2026
Document Type
Directed Research Project
First Advisor
Michelle R. Peace
Abstract
Despite ongoing efforts by the U.S. Food and Drug Administration (FDA) to regulate electronic cigarettes (e-cigs), thousands of unregulated products associated with significant quality assurance gaps remain in the market. Microbial toxins detected in e-cig liquids (e-liquid) have been linked to unsanitary manufacturing practices, improper storage conditions, and contaminated raw materials. Inhalation exposure to such toxins may pose significant health risks, including fever, rash, gastrointestinal illness, respiratory disease, and in severe cases, death. This study characterized the types and relative abundance of bacterial and fungal organisms associated with e-cigs. It included the analysis of e-liquids confiscated from high school and middle school students and commercially purchased e-cigs, as well as aerosols generated from those devices. The second part of the study tested whether e-liquids themselves could support bacterial growth without any other exogenous nutrients. Vaping products confiscated during the 2024–2025 school year were categorized by Virginia’s five health districts, product composition, and mouthpiece cleanliness. E-liquids and aerosols, collected using an in-house trapping system, from confiscated (n = 109) and purchased (n = 7) devices were tested for yeast, mold, aerobic count (AC), Escherichia coli, and coliform. Samples were considered positive based on United States Pharmacopeia (USP) regulatory thresholds. Bacterial propagation was assessed using a Cerillo Stratus Kinetic Microplate Reader, where Bacillus cereus T-strain was spiked into individual e-liquid matrices and optical density was measured over time. Microbes were detected in approximately 30% of confiscated e-liquids and aerosols analyzed (total n = 133), with 16% exceeding regulatory thresholds, demonstrating that microbes, if present in the e-liquid or on the external device, are successfully aerosolized and remain viable. Three devices exhibited microbial growth in both matrices. In e-liquids, colony forming units (CFU) per mL ranged from 0–20 for yeast, 0–50,000 for mold, 0–400,000 for AC, and 0–1,100 for coliform. In aerosol samples, CFU/g ranged from 0–22 for yeast, 0–19 for mold, and 0–2,288 for AC. No microbial growth was detected in purchased products. Among e-liquid components, cannabidiol (CBD) showed slight bacterial propagation (average change in optical density [ΔOD] = 0.086), suggesting that continued use may increase bacterial exposure during inhalation; however, overall low e-liquid bacterial counts and limited propagation suggest that microbes detected in aerosols likely originate from external parts of the device. These findings highlight health risks associated with exposure to e-cigs containing microbes, particularly among adolescents, and emphasize the need for improved regulation and education.
Rights
© The Author(s)
Is Part Of
VCU Master of Science in Forensic Science Directed Research Projects
Date of Submission
4-17-2026