The study, published Wednesday in the scientific journal Environmental Health Perspectives by researchers from Johns Hopkins University’s Bloomberg School of Public Health, sampled 56 vape devices. They gathered these e-cigs from actual vapers who they recruited for the study at smoke shops and vape conventions. Prior studies have only looked at newly purchased e-cigs, and the authors of this study wanted to test devices that people actually use for more accurate samples.

The study’s authors tested three elements of the e-cigs: the liquid itself, the liquid inside of the vape pen’s chamber, and the aerosol (or vapor). They were specifically interested in whether the metal coil that vape pens use to heat the liquid in order to turn it into vapor was leeching or generating toxic metals.

There was not a significant amount of toxic metals in the e-cig liquid itself. But in over half of the e-cigs, the liquid inside the dispenser and the aerosol contained significant levels of chromium, nickel, and lead. According to the study’s authors, chromium and nickel have been linked to respiratory disease and lung cancer. And lead can cause neurotoxicity and cardiovascular disease — there is also no safe amount of lead exposure.  Proving the initial hypothesis right. But that’s not the only thing they found. It turns out even the liquid used in the e-cigs contains traces of arsenic, which raises questions of why for those who are trying to quit smoking it is necessary to be intaking the main toxic (found in cigarettes) even in the shape of a vape?

“It’s important for the FDA, the e-cigarette companies and vapers themselves to know that these coils, as currently made, seem to be leaking toxic metals—which then get into the aerosols that vapers inhale,” study senior author Ana María Rule, PhD, MHS, an assistant scientist in the Bloomberg School’s Department of Environmental Health and Engineering, said in a statement.

There are studies which exist as public knowledge, which talk about how vaping is healthier than smoking and the percentage of deaths from vaping is 1% of rate of deaths from smoking cigarettes. Here is another fact added to the public knowledge long list of things, it’s good to be aware.