Someone smokes an e-cigarette. Vapor is blown out of the person's mouth.
Think vaping is a safe alternative to tobacco cigarettes? Not likely. New research suggests e-cigarette vapor contains heavy metals. (For Spectrum Health Beat)

If you think that “vaping” is a safe alternative to smoking, new research suggests you might be inadvertently inhaling unsafe levels of toxic metals.

Scientists say the tiny metal coils that heat the liquid nitrogen in e-cigarettes may contaminate the resulting vapor with lead, chromium, manganese and nickel. The finding raises the possibility that e-cigarettes are not harmless to users.

“We analyzed 15 metals in e-liquid from the refill dispenser—before the liquid meets the heating element—in the vapor, and in the remaining e-liquid in the tank after vaping,” explained study author Pablo Olmedo. He’s an assistant scientist with the Johns Hopkins School of Public Health’s department of environmental health and engineering, in Baltimore.

“We found that the metal concentrations were generally higher in the tank and aerosol compared to the refill dispenser,” said Olmedo. That suggests that the heating coil is the smoking gun, he added.

But study co-author Ana Maria Rule pointed out that their team also found “the presence of some metals in some of the liquids even before they are in contact with the coil.”

That could mean that “in addition to the metal coil, other factors could play a role in e-cigarette metal exposure, such as the voltage used to heat the coil,” said Rule, also an assistant scientist at Hopkins.

Unlike traditional smoking, vaping works by heating liquids that contain nicotine. The liquid passes through a heating coil, producing a vapor that proponents claim is free of much of the carcinogens associated with burning tobacco leaves.

Given that a recent U.S. National Institute on Drug Abuse survey found that one in six high schoolers has vaped in the past month, the finding could have broad public health implications, the researchers said.

In the Hopkins study, published in the journal Environmental Health Perspectives, investigators recruited 56 vapers in the Baltimore area to see whether the heating process introduces toxins into what is inhaled.

The researchers used the vapers’ own e-cigarette devices when examining the chemical content of e-liquid, vapor and residue.

Tested chemicals included: aluminum, antimony, arsenic, cadmium, chromium, copper, iron, lead, manganese, nickel, titanium, tungsten, uranium and zinc. Prior research has linked prolonged inhalation of such metals to lung, liver, heart and brain damage.

Chronic exposure may also depress immune system function and raise the risk for certain types of cancer, the researchers said.

The team found that e-liquid exposed to heating coils produced a vapor containing significant amounts of chromium, lead, manganese, nickel and zinc.

Highly toxic arsenic was also found in both the e-liquid and the heated vapor among a subset of 10 vapers, though how that metal got into the unheated e-liquid remains unclear.

The team also noted that toxic metal levels seemed to be higher among vapers who changed their heating coils more often, suggesting that new coils may produce more toxins than older ones.

Regardless, Rule said, vapers should know that “as far as we know, all current electronic cigarettes use a metallic coil to generate the vapor, so not vaping is the only way to avoid or mitigate this (toxic) exposure.”

As for whether vaping is safer than smoking or worse, Rule said the team “did not set out to compare e-cigarettes to cigarettes.”

But Stanton Glantz, a professor of medicine with the University of California, San Francisco’s Center for Tobacco Control, Research and Education, said it’s important to understand that e-cigs “have an entirely different toxicological profile” than cigarettes.

“So the risk profile is going to be different,” Glantz said. “The assumption has been that at least e-cigarettes aren’t worse. But this suggests they have something in them that isn’t even in standard cigarettes that’s worth being worried about.”

That worry was echoed by Patricia Folan, director of the Center for Tobacco Control at Northwell Health in Great Neck, New York.

“Considering the list of metals, toxic materials and lung-damaging materials found in e-cigarettes, these products are not a healthy product for teen consumption,” she said.

“I guess the question is, do we really want to promote and advertise these products and take a chance on damaging the health of our youth, without knowing their health effects and without regulation?” Folan asked.