Electronic cigarettes, or e-cigarettes, have become a popular alternative to regular cigarettes for habitual tobacco users. Citing convenience and the belief in improved safety, many smokers have readily adopted this new technology. Electronic cigarettes work by heating a liquid solution of nicotine and flavorings using a battery-powered heating coil until the liquid forms a vapor. The vapor is inhaled, hence the often-used term for the behavior – “vaping.” Thus, no smoke is inhaled, lending itself to the assumption that it is kinder to the lungs.

Some types of e-cigarettes have batteries that can be recharged, while the disposables are thrown away after the battery life ends. The present study used the disposable variety as their test subject. Researchers wanted to compare regular cigarette smoke to the content of e-cigarette and e-hookah “aerosol” — particles suspended in the vapor. The content of the e-cigarette vapor had not been studied in detail until now, and the results are intriguing.

The researchers set up a rigorous experiment to compare the metals and plastics of the internal components of the disposable e-cigarettes to the elements that appeared in the vapor. They disassembled several brands of e-cigarettes and used a very high powered microscope called an electron microscope and other sophisticated tools to determine the chemical makeup of the coil, circuits, battery, shaft, wires, and insulation. After that, they “puffed” on the e-cigarettes at the same volume at regular intervals using a smoking machine that simulates a human mouth but instead collects the vapor into a flask for analysis.

To account for varying amounts of metals and other elements that may leach into the e-cigarette vapor over time, the researchers compared the content of the first 60 puffs with the last 60 puffs of the battery’s lifespan. Researchers also compared small puffs with larger puffs to observe if the quantity inhaled has an effect on the metals and elements present.

The above experiments were repeated using a popular brand of conventional cigarettes. The unaltered air in the room was also gathered for a control. The contents of the room air were subtracted out of the final results, so only the chemicals in the smoke and vapor were considered.

Of the eleven brands of cigarettes and hookahs studied, 35 unique metals and elements were found. Silicon was the most abundant, likely originating from post-manufacturing dust on the wick and insulating sheath and particles that break off during repeated heating and cooling. The amount of silicon in the vapor decreased with use of the device.

The elements calcium, sodium, copper, magnesium, tin, lead, zinc, boron, selenium, aluminum, iron, germanium, antimony, nickel and strontium were found in electronic smoking devices at higher concentrations compared to regular cigarettes. These elements likely originated from the wires, solder, braces, and other internal components. Significantly different quantities of these metals varied across the brands studied, puff size, and device age. View the figures in the paper for the content of specific brands under different conditions, which are summarized in pie charts here, here, here, and here.

Perhaps what is most intriguing about these results is that while e-cigarettes had a greater variety of metals and elements in their vapor, conventional cigarettes had a higher total concentration of metals and elements. It begs the question – Does this mean conventional cigarettes are “worse” than electronic cigarettes, or the other way around?

The health implications of studies like this are hard to pin down. The authors cite previous research which show negative health effects associated with many of the metals and elements they recovered. The Environmental Protection Agency’s (EPA) recommended maximum exposure limits do not take into account recreational inhalation – only occupational. That means the EPA is concerned with work related exposures rather than what someone would be exposed to from smoking habitually. Some of the elements found in the vapor did exceed those levels. A higher total concentration of metals could be worse, but if the metals present are overall less toxic to humans, then the comparison becomes more difficult. E-cigarettes could contain certain metals not present in regular cigarettes that are harmful even at very small concentrations. It is critical to establish known toxicity levels and their health effects in humans due to recreational use before scientists can decide confidently which device bears greater risk.

Nevertheless, more research is still required to determine definitely if vaping is the healthier smoking option. Regardless of your opinion, we can all agree that being an informed consumer goes a long way.