Ecotoxicological effects of leachate from e-cigarettes and e-liquid on the performance of perennial ryegrass (Loliumperenne)

Once littered, disposable e-cigarettes present a complex type of waste in the environment. They typically contain a lithium battery, electronics to produce vapour and remnant e-liquid, all of which could leach into the environment. The effects of littered e-cigarettes are not well understood, and they have not been tested in terrestrial ecosystems. To address this, an experiment was set up to assess how leachate from e-cigarettes with or without a battery, but also e-liquid on its own can alter fundamental physical characteristics of Lolium perenne (perennial ryegrass) when irrigated with contaminated water. After 31 days, shoot length of L. perenne was not measurably affected, but the biomass was significantly reduced by 30% when e-liquid, and 24% when leachate from intact e-cigarettes was present compared to control plants. Plants grown with leachate or e-liquid displayed a significant level of early senescence of leaf apices, and the chlorophyll content was increased. Furthermore, root biomass was significantly less (29-46%) compared to the control. Leachate from used disposable e-cigarettes can affect the performance of plants when entering the soil ecosystem, therefore stricter regulations are needed to prevent this new type of electronic litter from becoming more widespread.

Disposable e-cigarettes and cigarette butts alter the physiology of an aquatic plant Lemna minor (Lemnaceae)

Cigarette butts are one of the most littered single-use plastic items worldwide and can have ecotoxicological effects. e-Cigarettes (or 'vapes') have gained popularity globally as an alternative to tobacco-based cigarettes in recent years. The increased availability of disposable e-cigarettes has resulted in a rise in their littering, presenting a complex form of e-waste in the environment, yet the environmental impacts of littered e-cigarettes are largely unknown. Here Lemna minor (common duckweed) was used as a model organism to understand the effects of smoked cigarettes, vaped e-cigarettes or e-liquid. Growth-related physiological responses were measured (biomass, root development and frond chlorophyll content). After 14 days of exposure to cigarette butts there was an increase of all measured growth variables. On the contrary, exposure to e-cigarettes or e-liquid caused a decrease in root length, biomass and frond number relative to controls. The significant deviations from control conditions suggest that the presence of either cigarette butts, e-cigarettes or e-liquid caused stress to the model plant which could indicate disruption of aquatic ecosystems at the primary producer level. Disposable vapes pose a novel threat to aquatic ecosystems and it would be prudent to prevent them from becoming the next top litter item.

Analysis of common methodological flaws in the highest cited e-cigarette epidemiology research

The prevalence of vaping, also known as using e-cigarettes, vapes and vape pens, has prompted a demand for reliable, evidence-based research. However, published literature on the topic of vaping often raises concerns, characterized by serious flaws and a failure to adhere to accepted scientific methodologies. In this narrative review, we analyze popular vaping studies published in medical journals that purport to evaluate the association of vaping and smoking cessation, smoking initiation or health outcomes. We analyzed 24 included studies to identify the questions they claimed to address, stated methods, manner of implementation, discussions, and stated conclusions. After critical appraisal, we noted a multiplicity of flaws in these studies, and identified patterns as to the nature of such flaws. Many studies lacked a clear hypothesis statement: to the extent that a hypothesis could be inferred, the methods were not tailored to address the question of interest. Moreover, main outcome measures were poorly identified, and data analysis was further complicated by failure to control for confounding factors. The body of literature on "gateway" theory for the initiation of smoking was particularly unreliable. Overall, the results and discussion contained numerous unreliable assertions due to poor methods, including data collection that lacked relevance, and assertions that were unfounded. Many researchers claimed to find a causal association while not supporting such findings with meaningful data: the discussions and conclusions of such studies were, therefore, misleading. Herein, we identify the common flaws in the study design, methodology, and implementation found in published vaping studies. We present our summary recommendations for future vaping research. Our aim is to prompt future researchers to adhere to scientific methods to produce more reliable findings and conclusions in the field of vaping research.