A man exhales electronic cigarette vapor in a park in central Kiev, Ukraine, May 12, 2017. Reuters/Valentyn Ogirenko

Alarming levels of metal substances like lead have been found in the heating coils of e-cigarettes, a new study has found.

Researchers at the Johns Hopkins Bloomberg School of Public Health conducted a study involving a sample group of 56 daily e-cigarette users from vaping conventions and e-cigarette shops around Baltimore. It was conducted by Pablo Olmedo, a postdoctoral researcher at the Bloomberg School and the lead author of the study along with a few other researchers.

During the study, the researchers tested for the existence of 15 metals in the heating coils of the vapers' refilling dispensers, the e-liquids in their coil-containing e-cigarette tanks and in the generated aerosols.

The study found that a significant number of the electronic devices produced dangerous levels of lead as well as chromium, manganese, and nickel. The lead concentration in the aerosols was more than 25 times greater than the level in the refill dispensers.

The researchers also stated that the consumption of these harmful metals was linked to various diseases including lung, liver problems, cardiovascular problems, and even cancer.

E-cigarettes come in various shapes and sizes. They are battery-operated and have a heating element and a place to hold a liquid. They produce aerosol by heating the liquid that contains nicotine. Nicotine is usually used in cigarettes, cigars, and other tobacco products, according to Centers for Disease Control and Protection (CDC).

According to the CDC website, e-cigarettes are also known as “e-cigs,” “e-hookahs,” “mods,” “vape pens,” “vapes,” “tank systems,” and “electronic nicotine delivery systems (ENDS).”

The website also states that e-cigarettes can contain “harmful and potentially harmful substances, including nicotine, heavy metals like lead, volatile organic compounds, and cancer-causing agents.”

The Food and Drug Administration (FDA) is yet to regulate e-cigarettes and have not yet figured out how to do so.

"It's important for the FDA, the e-cigarette companies and vapers themselves to know that these heating coils, as currently made, seem to be leaking toxic metals -- which then get into the aerosols that vapers inhale," Ana María Rule, Ph.D., MHS, an assistant scientist in the Bloomberg School's Department of Environmental Health and Engineering, and a co-author of the study said in a press release.

“This important study lends confirmation to the growing concern of clinicians, healthcare officials, and concerned citizens that current vaping instruments and e-cigarettes are not a safe and efficacious delivery modality for tobacco, and other loose leaf and oil-based substrates,” Rich Able, a medical device marketing consultant said.

"The metal and parts composition of these devices must be stringently tested for toxic analytes and corrosive compounds. The FDA does not currently test any of the most popular vaping and e-cigarette instruments being manufactured at unregulated factories in Asia that source low-grade parts, batteries, and materials for the production of these devices," Able added.

She further stated “the metals detected in this study have been associated with multiple adverse health effects under chronic conditions of exposure. Neurotoxins such as lead are linked to increased risk of cardiovascular and kidney disease. The other metals listed are even more nefarious to human organs. The strong oxidative effects of manganese can lead to necrosis (tissue death) of the mucous membrane and esophagus. Arsenic was detected in 17.9 percent of the aerosolized samples which can lead to significant multiple end organ damage with long-term exposure.”

The study was published in the journal Environmental Health Perspectives on Feb. 21.