Electronic cigarettes are no better than regular ones
Vaporizers surpassed cigarettes in genotoxicity
Denis Strigun, Naked Science
Chemists from the USA and Ireland have developed a new microfluidic sensor, which has shown that nicotine-containing vaporizers can have increased genotoxicity compared to conventional cigarettes. Article by Kadimisetty et al. Automated 3-D Printed Arrays to Evaluate Genotoxic Chemistry: E-Cigarettes and Water Samples is published in the journal ACS Sensors.
Despite the relatively long history of production, the side effects of e-cigarettes remain unclear. Due to the absence of resins and heavy metals in the liquid for them, manufacturers position such devices as a less harmful alternative to conventional cigarettes. However, past work has shown that the spread of vaporizers does not reduce the number of nicotine-dependent, and aromatic substances can increase the toxicity of steam. Thus, during pyrolysis, the latter is split into aldehydes, which suppress the expression of genes of the nasal mucosa and, as a consequence, the immune response. At the same time, there are no cheap and affordable systems that allow for the analysis of the genotoxicity of steam.
In 2012-2016, American chemists created and tested prototypes of disposable microfluidic arrays for automated toxicity screening of various drugs. They are electrochemical or electrochemiluminescent sensors based on paper or carbon. In the case of the latter, DNA and human metabolic enzymes are placed in the wells located on the surface of the sensor, which, when mixed with the target substance, produce new, often genotoxic metabolites. During the production of toxins, the samples emit a glow recorded using a CCD matrix. In the new work, the authors have created a more complex reusable system.
The principle of operation of the sensor (here and below are the pictures from the article in ACS Sensors).
To develop a new sensor, scientists used a desktop 3D printer. By stereolithography, they printed a microfluidic array with three chambers made of acrylic resin, which fed the solution into three microchannels using micro pumps. From there, the target liquid was fed into wells (seven in each of the three rows) on a pyrographite sensor. The presence of genotoxic metabolites was recorded by a CCD camera. The system worked automatically: the activity of three micro pumps was provided by an 8-bit microcontroller with a lithium-ion battery. Human DNA and ruthenium polyvinylpyrrolidone (RuPVP), a source of liver microsome enzymes, were cultured in the wells.
The sensor was tested on 20, 60 or 100 "puffs" with conventional (with and without a filter) and electronic cigarettes (with nicotine-containing and nicotine-free liquid), which were collected by means of an inhalation device. Each channel was evaluated depending on the reaction to certain compounds, in particular, polyaromatic hydrocarbons, benzpyrene, nitrosamines NNK and NNN – the main carcinogens characteristic of tobacco smoke. Additionally, the sensor was tested on wastewater. The results showed that the treatment with extracts caused significant dose-dependent DNA damage. Moreover, the chemiluminescence of the samples after nicotine-containing vapor exceeded the indicator of cigarettes with a filter.
Comparison of electrochemiluminescence (ECL) caused by genotoxic metabolites after treatment with a control substance (DMSO), cigarette smoke with a filter (Tobacco Cig., TC), without a filter (nf-Tobacco Cig., nf-TC), nicotine-free vapor (nn-Electronic Cig., nn-EC) and nicotine-containing (Electronic Cig., EC) electronic cigarettes. Diagram C shows the proportion of NNK in the glow of samples after different types of cigarettes.
Subsequent analysis confirmed that the DNA damage caused by nicotine-containing steam treatment was at least identical to the effects of unfiltered cigarettes. With the increase in the number of "puffs" (from 60, which corresponds to three cigarettes), the negative impact of such vaporizers turned out to be greater than that of conventional cigarettes. At the same time, cigarettes without a filter led to the production of 1.8 times more genotoxic metabolites than electronic cigarettes without nicotine and cigarettes with a filter.
The danger of wastewater depended on the degree of purification. Thus, the genotoxic potential of untreated samples was ten times higher than that of fully regenerated and 2.4 times higher than that of partially regenerated water.
According to the authors, the data obtained supplement information about the potential risks associated with nicotine-containing vaporizer liquids. The work also demonstrates a new inexpensive and fast method of chemical analysis of drugs. Printing the sensor cost scientists 80 cents and took less than an hour. Each analysis took only five minutes.
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14.06.2017