Electronic cigarettes, which consist of a battery, atomizing unit and refill the fluid, are now available in new tank-style designs, equipped with more powerful batteries and larger capacity reservoirs for storing more refill fluid.
But the high-power batteries and atomizers used in these new styles can alter the metal concentrations that transfer into the aerosol, said researchers from the University of California, Riverside.
"These tank-style e-cigarettes operate at higher voltage and power, resulting in higher concentrations of metals, such as lead, nickel, iron, and copper, in their aerosols.
"Most of the metals in e-cigarette aerosols likely come from the nichrome wire, tin solder joints, brass clamps, insulating sheaths, and wicks, components of the atomizer unit," said Monique Williams, a post-doctoral researcher and the first author of the paper that appeared in the journal Scientific Reports.
The researchers examined six tank-style electronic cigarettes and found all the aerosols had metals that appeared to originate in the atomizers.
Further, they found the model with fewest metal parts in its atomizer had the fewest metals in its aerosol.
Of the 19 metals they screened, aluminium, calcium, chromium, copper, iron, lead, magnesium, nickel, silicon, tin and zinc were from components in the atomizing units.
"We found the concentrations of chromium, copper, lead, nickel, and zinc exceeded the proposed permissible exposure limit from the Occupational Safety and Health Administration," Williams said.
Chromium, lead, and nickel are known as carcinogens. Prolonged exposure to chromium could cause gastrointestinal effects, nasal and lung cancer, respiratory irritation, and lung function impairment.
Prolonged exposure to lead could produce vomiting, diarrhoea, cardiovascular effects, and lung cancer.
Nickel inhalation could cause lung disease, damage to the nasal cavity, lung irritation, lung inflammation, hyperplasia in pulmonary cells and fibrosis.
The researchers have analyzed the following six tanks and their atomizers: Kangertech Protank, Aspire Nautilus tank, Kanger T3S tank, Tsunami 2.4, Smok tank and Clone.
"The presence of heavy metals, including some known carcinogens, in e-cigarette aerosols is concerning because with prolonged exposure they could cause adverse health effects," said Prue Talbot, a professor of cell biology, who led the research team.
( With inputs from IANS )