Analysis Shows Metals Emitted from E-Cigarettes Are Within Safety Limits
Several studies have reported the presence of heavy metals in electronic cigarette aerosol, which is plausible due to the build structure of these devices. However the health impact they might have on users has not been properly defined. In order to shed some light on this issue, a team of Greek researchers led by Dr. Konstantinos Farsalinos conducted a through analysis, evaluating the exposure of e-cigarette users to heavy metals and comparing it with currently-available regulatory safety limits.
Dr. Farsalinos and his team searched the PubMed database for literature on metal emissions from electronic cigarettes and found nine studies, of which two focused on the emissions of heavy metals in the aerosol and another two evaluated environmental exposure. Since higher levels are found in the e-cigarette aerosol compared to the environment, researchers decided to analyze the former two studies.
Goniewicz et al (2014) measured heavy metal emissions of 12 electronic cigarettes and compared them to emissions from pharmaceutical nicotine inhalers. Only three metals were detected in e-cig aerosol – cadmium, lead and nickel. Williams et al (2013) evaluated the emissions of several metals from a cartomizer and reported the results in amount for 10 puffs. This study detected the presence of the following metals in the aerosol: aluminum, barium, chromium, copper, iron, lead, manganese, nickel, strontium, tin, titanium, zinc and zirconium. The authors of this latter study did not clarify if the reported values included a subtraction of levels found in room air, or concentrations of metals found in room air.
To asses the health risk of the estimated exposure to these elements, Dr. Farsalinos and his team used the Permissible Daily Exposure (PDE) from inhalational medications, defined by the United States Pharmacopeia (USP) for cadmium, chromium, copper, lead and nickel, the Minimal Risk Level (MRL) defined by ATSDR (Agency for Toxic Substances and Disease Registry) for manganese, and the Recommended Exposure Limits (RELs) defined by NIOSH (National Institute for Occupational Safety and Health) for aluminum, barium, iron, tin, titanium, zinc and zirconium.
In order to adequately evaluated the exposure to heavy metals from electronic cigarette aerosol, a number of daily puffs had to be calculated as well. According to a study evaluating e-cigarette topography, the average consumption is 5 mg per puff, using a clearomizer. A worldwide survey of 19,000 e-cigarette users revealed an average daily consumption of 3 g, so the scientists were able to calculate an average use of 600 puffs per day. However, an uncertainty factor of 2 was also used to address inter-individual variability, thus the an exposure from 1,200 electronic cigarette puffs was estimated. On his blog, Dr. Farsalinos emphasizes that this was an overestimation to make the analysis more rigorous.
To analyze the daily exposure to metals, the levels found by Williams et al (reported for 10 puffs) were multiplied by 120, while those in the Goniewicz study (reported for 150 puffs) were multiplied by 8, after subtracting the reported environmental levels.
Even with the extreme number of daily puffs estimated in this analysis, researchers found that the average daily exposure levels to cadmium, chromium, copper, lead and nickel from electronic cigarette aerosol were 2.6-37.4 times lower compared to acceptable intake from inhalational medications. Exposure to managanese was 325 times lower than the Minimal Risk Level (MRL), while levels of aluminum, barium, iron, tin, titanium, zinc and zirconium were 665-77,500 times lower compared to the Recommended Exposure Limits (RELs).
“The levels of metals emitted to the EC aerosol, as found in currently available literature, are unlikely to generate significant adverse health effects for smokers switching to EC use,” the researchers concluded.
There are some other things to consider. Like the fact that both Goniewicz et al and Williams et al used first generation electronic cigarettes and atomizers. Vaping technology has evolved a lot in the last few years, and the use of new materials like stainless steel and pyrex glass is likely to result in considerably lower metal emissions in the aerosol. Studies involving newer vaping devices are desperately needed to confirm this theory, but, as Dr. Konstantinos Farsalinos notes, e-cigarette companies seem more interested in pumping large sums of money into marketing than investing in research.
Furthermore, the large difference in emissions observed between different devices clearly shows there is lots of room for improvement. Companies should strive to improve the quality of their products in order to reduce unnecessary exposure to metals.
Source: International Journal of Environmental Research and Public Health
