If you use an electronic cigarette, you’re getting more than a jolt of nicotine. That vapor also includes what researchers say is a significant amount of lead and other toxic metals.

A sample of e-cigarettes used by 56 people found many devices generated aerosols with potentially unsafe levels of nickel, lead, chromium and manganese. Repeatedly inhaling these metals has been linked to cardiovascular, lung, liver and brain damage. The findings by Johns Hopkins University scientists were published in the journal Environmental Health Perspectives.

E-cigarettes use a battery-powered current to heat a liquid that contains nicotine and flavorings. That creates a vaporized cloud that is inhaled — commonly known as vaping.

The study participants brought their devices to the researchers’ labs for analysis. The team tested for metals in the vapers’ refill dispensers, in the e-cigarettes’ liquid tank and in the aerosol clouds. The median lead concentration in the aerosols was more than 25 times greater than the median level in the refill dispensers. Almost half of the aerosol samples had lead levels that exceeded recommendations by the U.S. Environmental Protection Agency, which is still deciding how to regulate e-cigarettes.

Researchers said the heating coils on some e-cigarettes appear to be leaking metals, which then get into the aerosols that users inhale. They also noted that more metals were found in e-cigarettes that had frequently changed coils, suggesting that newer coils may leach metals more easily.

If you choose to vape, be aware there’s more than just nicotine in that puffy white cloud you’re inhaling.