Smoking e-cigarettes delivers cancer-causing chemicals that get into the body — and popular fruity flavors appear to be the worst, researchers reported Monday.

They said teenagers who try vaping are poisoning themselves with many of the same chemicals that make traditional cigarettes so deadly.

Tests on teenagers show that those who smoke tobacco-based cigarettes have the highest levels of these chemicals in their bodies, but those who vape e-cigarettes also have higher levels of the cancer-causing chemicals than nonsmokers, the team at the University of California, San Francisco, found.

“The presence of harmful ingredients in e-cigarette vapor has been established‍; we can now say that these chemicals are found in the body of human adolescents who use these products,” they wrote in their report, published in the journal Pediatrics.