Recently, there has been a shift away from calling e-cigarettes “e-cigs.” In public health circles, people now tend to call them by what they do: deliver nicotine to the inhaler. Thus, the term Electronic Nicotine Delivery Systems, ENDS for short, has come into vogue.

But I have a problem with that name. Nicotine isn’t the only thing e-cigs deliver; they also deliver formaldehyde, a carcinogen. It seems equally fair to call them Electronic Formaldehyde Delivery Systems.

Do manufacturers intentionally put formaldehyde in e-cigs? No, they don’t. But there’s some fundamental chemistry happening that can generate formaldehyde. E-cigs often use propylene glycol or glycerol to help transport nicotine and flavors and to create the big vapor cloud. We’ve known for a long time that when we heat these so-called carrier fluids they can transform into formaldehyde.

Sure enough, when we measure what’s coming out of an e-cigarette, we have found formaldehyde. Sometimes, a lot of it. A letter published in the New England Journal of Medicine caught widespread attention in 2015 when its authors reported that they had found emissions of formaldehyde from e-cigs. There was some initial push back from skeptics who claimed that the e-cig vaping conditions in the research used too high of a voltage (an actual user, they argued, would be deterred from puffing hard enough to generate the excessive formaldehyde because it would taste bad). Of note, one author of that critique receives funding from a group that has accepted money from tobacco companies, and another received money from an e-cig company.