E-cigarettes seem to be on a popularity binge, and there’s no end in sight. As more people pick up e-cigarettes, the U.S. Food and Drug Administration (FDA) and other public health agencies around the world are struggling to decide the best route to take to regulate the products, which don’t burn tobacco, don’t emit smoke; and most importantly, don’t have enough evidence suggesting they’re just as harmful as cigarettes. Now, as France is on the verge of banning e-cigarettes just like regular ones, French magazine, 60 Millions de Consommatuers (60 Million Consumers), says that it found some toxins at or above levels normally found in cigarettes.

“Electronic cigarettes are far from the harmless gadgets they’re sold as to manufacturers,” wrote Thomas Laurenceau, chief editor of the magazine, according to France24, after testing 10 e-cigarettes that were either reusable or disposable. “It’s not a reason to ban them, but to better control them.”

The magazine reports the findings of France’s National Consumer’s Institute (INC). After testing for carcinogenic molecules in 10 e-cigarettes’ vapor, three models tested positive for the chemical formaldehyde at levels close to those in typical cigarettes. The tests also showed presence of the toxic compound acrolein, which changes to vapor when heated, and has been shown to damage the lungs. For some e-cigarettes, acrolein levels were higher than in normal cigarettes.

The tests also found that nicotine levels were higher in some products than their labels stated, while presence of the chemical propylene glycol, which is used to vaporize the nicotine, was sometimes not labeled.

Still, many argue that e-cigarettes aren’t harmful—or at least not as much as regular tobacco. According to the Tobacco Vapor Electronic Cigarette Association, “the e-cig industry and non-industry affiliated laboratories have done extensive testing on the e-cig and in not one test (inclusive of the FDA’s own May 4, 2009) has there ever been found a single ingredient or toxin in any samples that is harmful to humans.”

In May, French Health Minister Marisol Touraine announced that e-cigarettes would be banned from public areas in much the same way that regular cigarettes have been since 2007. In the U.S., director of the FDA’s Center for Tobacco Products, Mitch Zeller, told The Wall Street Journal that he’s looking into possible regulations, including banning online sales to keep them out of minors’ hands, and possibly regulating TV, print, and other advertising channels. He said they’d be ready by October. “It is true that more research is needed on the health effects of e-cigarettes. However, we do not need more research on whether e-cigarettes should or should not be included in proposed FDA regulations.”