Here's more disturbing news for vapers. Their DNA shows chemical changes similar to those found in smokers, changes that may be cancer-related.

“That doesn't mean that these people are going to develop cancer,” said Ahmad Besaratinia, co-author of a recent study that detected these changes. “But what we are seeing is that the same changes in chemical tags detectable in tumors from cancer patients are also found in people who vape or smoke, presumably due to exposure to cancer-causing chemicals present in cigarette smoke and, generally at much lower levels, in electronic cigarettes' vapor.”

The changes observed were epigenetic. Unlike mutations, which vary the DNA sequence, epigenetic modifications are chemical alterations in DNA that do not change the DNA sequence but may greatly change how active a particular gene is. A common epigenetic change is the addition of a small chemical tag, such as a methyl group, to the DNA in a particular gene.

Specifically, this study looked at methylation of DNA sequences known as Long Interspersed Nuclear Elements (LINES).

LINES are pieces of DNA that sometimes have the capability of moving — starting out in one area of the DNA and ending up at a different location, often causing mutations and even cancer when they do move. These sequences tend to be heavily methylated, which greatly limits the probability that they will move and cause havoc.

In the current study, both vapers and smokers showed significant loss of methylation in LINE-1 sequences.

Both smokers and vapers also showed similar reductions in another type of epigenetic modification, a decrease in hydroxymethylation throughout their entire genome. Addition of a hydroxymethyl group to a gene, like methylation, tends to reduce the activity of that gene.

This study adds to previous work from the same lab, which found other abnormal changes in gene expression in cheek cells taken from both smokers and vapers.

Besaratinia, an associate professor at the University of Southern California's Keck School of Medicine, and his team plan to continue their research, with the next step being to look at the whole genome and identify all the genes that have changed in vapers and smokers and compare the changes between these two groups of people. This will hopefully give us a clearer picture of just what the epigenetic changes vaping brings actually mean.

The study appears in Epigenetics.