# Characterization of Potential Harm Caused by Electronic Cigarette Flavor Chemicals and their Reaction Products

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA RIVERSIDE · 2020 · $694,308

## Abstract

Project Summary
Electronic cigarettes (ECs) use heat to aerosolize “e-liquid” mixtures that usually contain high concentrations of
flavor chemicals. This project will purchase 650 commercial e-liquids to: a) identify and quantify the flavor
chemicals used plus their degradation reaction products (RxPs) formed upon vaping; and b) evaluate the
cellular responses to those flavor chemicals often found at >1 mg/ml (viz. “dominant flavor chemicals”, DFCs),
and to the aerosols produced on vaping. Tested will be 550 “popular” refill and cartomizer fluids and 100 fluids
that have been anecdotally reported to cause sickness in users. Work will be conducted at two campuses:
Portland State University for analytical chemistry, and University of California Riverside for human toxicology.
Aim 1 (PSU). DFCs and vaping RxPs will be identified and quantified for the 650 fluids. Aerosols made using
a range of devices at varied power will be collected in isopropanol and analyzed using gas chromatography/
mass spectrometry (GC/MS) and liquid chromatography/MS/MS. Identification will proceed with standards.
RxPs formed from flavor chemicals will be unambiguously distinguished from RxPs from the EC solvents.
Aim 2 (UCR). Vape aerosols made using lab-prepared fluids containing the identified DFCs will be made with
a range of devices, and screened for cytotoxicity in dose-response experiments using in vitro assays in
conjunction with BEAS-2B lung epithelial cells from normal human adults. The aerosols that are most cytotoxic
will be studied in depth using an air-liquid interface exposure system with the 3D EpiAirway platform that
recapitulates human respiratory epithelium. Individual DFCs will be tested using six cancer-related mode-of-
action assays including assays for an epithelial to mesenchymal transition (EMT) that we have observed with
some EC products. Alterations in gene expression will be determined using RNA-seq and affected pathways
identified. Mixtures of DFCs will be tested at the same relative proportions found in consumer products.
Aim 3 (UCR). Since Aim 2 will examine heat generated aerosols, both DFCs and their RxPs products will have
been present. Aim 3 will differentiate the DFCs and RxP toxicities by exposing the 3D EpiAirway platform to
aerosols generated without heat and containing individual DFCs or the identified RxPs from heating. Endpoint
assays will proceed as in Aim 2 to isolate toxicity to individual chemicals.
Summary. Little is known about the health effects of flavor chemicals used in ECs. This project will fill an
important informational gap with comprehensive new data. Specific toxicants will be identified and the effects
of mixing DFCs will be evaluated. Results will be posted on an online database that will be accessible to any
interested persons or organization, and will provide foundational information for future understanding of flavor
chemicals in tobacco products. The data, the first of their kind, will contribute to a foundation...

## Key facts

- **NIH application ID:** 9967066
- **Project number:** 5R01ES029741-03
- **Recipient organization:** UNIVERSITY OF CALIFORNIA RIVERSIDE
- **Principal Investigator:** Prudence Talbot
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $694,308
- **Award type:** 5
- **Project period:** 2018-09-20 → 2023-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9967066

## Citation

> US National Institutes of Health, RePORTER application 9967066, Characterization of Potential Harm Caused by Electronic Cigarette Flavor Chemicals and their Reaction Products (5R01ES029741-03). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9967066. Licensed CC0.

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