Toxicological evaluation of vape liquids circulating in Brazil: Evidence of emerging hazards

The increasing recreational use of Electronic Nicotine Delivery Device (ENDS) poses a serious public health threat, with clear evidence of adverse health effects. Studies over the past 15 years have confirmed the presence of hazardous compounds in the emissions from e-cigarettes and e-liquids. In Brazil, where sales are banned but use is not, this is the first comprehensive study on ENDS in the country. E-liquids were collected through direct user donations and systematically categorized by their origin: Brazil, China, Europe, Paraguay, and the United States. Toxicity assessments were conducted using Saccharomyces cerevisiae and rat cardiomyoblasts. Our findings unequivocally establish that the toxicity of e-liquids escalates with increased concentrations across all samples and groups, with cytotoxic concentrations for 50 % growth inhibition (CC₅₀) values ranging (in percentage mass/volume) from 3.8 for the Paraguayan sample to 20.4 for the European sample. Cytotoxicity assessments in R9c2 cells demonstrate that toxicity intensifies with higher concentrations and the presence of additives, resulting in oxidative stress and apoptosis. Exposure (in percentage mass/volume) to 2.5 of e-liquids led to statistically significant changes compared to the unexposed group, with increased production of reactive oxygen species (ROS), release of lactate dehydrogenase (LDH), and inhibition of catalase enzyme activity. Significant toxicity was observed in products from both countries where sale is prohibited and countries where it is regulated. Evidence confirms e-liquids have distinct toxicity profiles based on their concentration and composition. Immediate action and increased public awareness are needed.