Evaluation of e-liquid toxicity using an open-source high-throughput screening assay

Introduction:
This article presents a study that aimed to evaluate the toxicity of e-liquids used in electronic cigarettes (E-cigs) and their impact on human health. The study developed a high-throughput screening (hTS) assay to rapidly triage and validate the toxicity of multiple e-liquids and analyzed the chemical composition of e-liquids using gas chromatography-mass spectrometry (GC-MS). The study also identified the factors associated with higher toxicity values and developed a publicly available searchable website ([www.eliquidinfo.org](http://www.eliquidinfo.org)) to facilitate the dissemination of the information.

Key Points:

* The study developed a 3-phase, 384-well, plate-based, high-throughput screening (hTS) assay to triage and validate the toxicity of multiple e-liquids.
* The study found that propylene glycol (PG)/vegetable glycerin (VG) vehicle adversely affected cell viability and that a large number of e-liquids were more toxic than PG/VG.
* GC-MS analysis revealed that e-liquids are an extremely heterogeneous group, and the more chemicals contained in an e-liquid, the more toxic it was likely to be.
* The presence of vanillin was associated with higher toxicity values, and the concentration of cinnamaldehyde and vanillin, but not triacetin, correlated with toxicity.
* The study also found that PG/VG by itself was toxic at higher doses.
* The study developed a publicly available and searchable website ([www.eliquidinfo.org](http://www.eliquidinfo.org)) that contains chemical composition and toxicity data.
* The hTS approach may serve as a roadmap to enable bodies such as the US Food and Drug administration (FDa) to better regulate e-liquid safety.

Main Message:
The study highlights the importance of evaluating the toxicity of e-liquids used in electronic cigarettes and the need for regulatory measures to ensure their safety. The study's findings suggest that an hTS approach to evaluate the toxicity of multiple e-liquids is feasible and may serve as a roadmap to enable bodies such as the FDa to better regulate e-liquid composition. The study's development of a publicly available and searchable website ([www.eliquidinfo.org](http://www.eliquidinfo.org)) containing chemical composition and toxicity data also facilitates the dissemination of information and promotes transparency in the e-liquid industry. Overall, the study emphasizes the need for further research and regulatory measures to ensure the safety of e-cigarettes and protect public health.

Sassano, M. Flori, Eric S. Davis, James E. Keating, Bryan T. Zorn, Tavleen K. Kochar, Matthew C. Wolfgang, Gary L. Glish, and Robert Tarran. “Evaluation of E-Liquid Toxicity Using an Open-Source high-Throughput Screening assay.” Edited by Chaitan Khosla. PLOS Biology 16, no. 3 (March 27, 2018): e2003904. https://doi.org/10.1371/journal.pbio.2003904.