And while e-liquid might not carry unsafe metals on its own, the team found just under a fifth of the samples had significant levels of another highly toxic element: arsenic. They found that the liquid in the e-cigarette, the liquid in the pen's chamber and the overall vapor itself releases carcinogens including chromium, lead, nickel and arsenic. But in over half of the e-cigs, the liquid inside the dispenser and the aerosol contained significant levels of chromium, nickel, and lead.
They found small amounts of some toxic metals in the liquids before use, but much higher levels were detected after the liquids had been exposed to the device's heating coils.
The Food and Drug Administration has the authority to regulate e-cigarettes but is still considering how to do so.
Those draws have made smoking e-cigarettes and other vaping devices attractive for young people who are turned off by tobacco, as well as for existing smokers looking for a way to keep the habit but ditch the health issues. In E-cigarettes, an electric current passes through a metal coil to heat "e-liquids", creating an aerosol vapor.
Researchers sampled 56 vape devices from real life vape smokers - not newer models that aren't subject to the same toxins - that proved heating up substances in plastic is actually very bad for you.
From the difference, it has been concluded that the metals had come from the coils. Four metals were excluded because of low levels: arsenic, titanium, uranium and tungsten. The Environmental Protection Agency said that nearly 50 percent of aerosol samples had lead concentrations higher than health-based limits.
The median lead concentration in the aerosols, for example, was more than 25 times greater than the median level in the refill dispensers. Nickel, chromium and manganese approached or exceeded safe limits, the researchers report. Subsequently, the study went further to analyze the vapor that users inhale in their lungs, which is generated by a metal coil that heats the liquid. "Due to potential toxicity resulting from chronic exposure to metals in e-cigarette aerosols, additional research is needed to more precisely quantify metal exposures resulting from e-cigarette use and their implications for human health, and to support regulatory standards to protect public health".
The full study has been published online in the journal Environmental Health Perspectives.
When e-cigarettes entered the market, a flurry of studies suggested they could be much safer than tobacco cigarettes. An earlier study had indicated that the flavorings in e-cigarettes could damage heart muscle. "We've established with this study that there are exposures to these metals, which is the first step, but we need also to determine the actual health effects".