"We collected it nearly as soon as it came out of the e-cigarette", study author Ana María Rule, PhD, MHS, told Men's Health.
The scientists in the most recent study say the median level of lead found in their sample was higher than the Environmental Protection Agency's safety standard, and that levels of other metals such as nickel, chromium and manganese "approached or exceeded safe limits". Newer versions however, allow daily users opt for reusable modified devices that allow them to refill the e-liquid from a dispenser.
E-cigarettes normally use a battery-supplied electric current that passes through a metal coil to heat nicotine-containing "e-liquids".
The Johns Hopkins team tested both the liquid in the e-cigarette dispensers and the aerosol users inhale into their lungs for 15 common metals. It found that toxic metals, including lead, leaked from a significant number of the heating coils of e-cigarette devices and were inhaled by users. Inhalation of these metals can result in problems with the lung, liver, cardiovascular, brain damage, and even cancers.
"Several shortcomings were found in a similar study conducted by the same institute previous year, including overestimating normal levels of exposure, not factoring in exposure to metals from daily activities, small sample size of products tested", Samrat Chowdhery, Director, Assocation of Vapers India (AVI), said in a statement. For example, the median lead concentration in the aerosols was more than 25 times greater than the median level in the refill dispensers. Researchers at Johns Hopkins Bloomberg School of Public Health studied the e-cigarettes of 56 individuals and almost half of them produced aerosol samples containing unsafe levels of lead in them.
The Food and Drug Administration has authority to regulate e-cigarettes, but is still considering how to do so, the researchers say.
"These were median levels only". "We don't know yet whether metals are chemically leaching from the coil or vaporizing when it's heated", she added.
The researchers did observe, however, that aerosol metal concentrations tended to be higher for e-cigarettes with more frequently changed coils-suggesting that fresher coils give off metals more readily.
The actual health effects of these exposure levels are still unknown and the researchers are planning further research into the impacts on humans, but numerous median aerosol concentrations identified in the study did approach or exceed the safe limits defined by the Environmental Protection Agency.
The researchers say they want to conduct more studies to more accurately determine the risks carried by e-cigarettes.