An advisory released by California officials on the health effects of electronic cigarettes raises new questions about the safety of these devices.

California health officials issued a health advisory this week on the dangers of electronic cigarettes. This warning coincides with a state Senate bill that would regulate the devices as tobacco products. At the same time, a ban on “vaping” on San Francisco’s public transit system awaits a final vote.

The health advisory and accompanying report by the California Department of Public Health (CDPH) said that, in addition to nicotine, the devices also emit cancer-causing chemicals and ultrafine particles that may cause inflammation in the lungs.

“E-cigarettes contain nicotine and other harmful chemicals, and the nicotine in them is as addictive as the nicotine in cigarettes,” said the department’s director and state health officer, Dr. Ron Chapman, in a press release. “There is a lot of misinformation about e-cigarettes. That is why, as the state’s health officer, I am advising Californians to avoid the use of e-cigarettes and keep them away from children of all ages.”

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Of particular concern is the use of electronic cigarettes by children and teens. In 2014, the Monitoring the Future survey, which tracks substance use in more than 40,000 young people, found that more teens use electronic cigarettes than conventional ones. During that year, 17 percent of high school seniors reported using electronic cigarettes.

The popularity of e-cigarettes among teens may lead new generations to nicotine addiction. “Without action, it is likely that California’s more than two decades of progress to prevent and reduce traditional tobacco use will erode as e-cigarettes re-normalize smoking behavior,” the CDPH report said.

The lure of electronic cigarettes is compounded by the fact that the liquids they burn — also known as “e-juice” or “e-liquid”— come in flavors such as bubble gum, chocolate, and cotton candy. Electronic cigarette companies market their products using cartoon characters and celebrity sponsorship, tactics previously used by tobacco companies to market traditional cigarettes to kids.

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Electronic cigarettes are battery-powered devices that heat a liquid containing nicotine into a vapor that can be inhaled. These cigarettes allow users to adjust the nicotine level and to use the same cartridge for extended periods.

In general, e-cigarettes emit fewer toxic chemicals than conventional cigarettes. But the CDPH report said that the vapor released by e-cigarettes contains at least ten chemicals known to cause cancer, birth defects, or other reproductive harm.

A recent article published in the New England Journal of Medicine also found that, at high temperature settings, electronic cigarettes might release more cancer-causing formaldehyde than conventional cigarettes. The research does not prove that electronic cigarettes are a health risk, but it does emphasize how little is known about these devices and what they emit.

The potential dangers of secondhand vapor have prompted California Senator Mark Leno to introduce legislation this week that would bring electronic cigarettes under the same restrictions as conventional ones. If the bill is passed, electronic cigarettes will be banned from public places such as hospitals, schools, and bars.

In addition, the Bay Area Rapid Transit (BART) board will take a final vote on Feb. 12 on a ban of electronic cigarettes on the BART train system. The public transit ban and the California Senate bill have received support from the American Cancer Society Cancer Action Network, the American Heart Association, and the American Lung Association.

“No tobacco product should be exempt from California’s smoke-free laws simply because it’s sold in a modern or trendy disguise,” said Leno in a press release. “Addiction is what’s really being sold. Like traditional cigarettes, e-cigarettes deliver nicotine in a cloud of other toxic chemicals, and their use should be restricted equally under state law in order to protect public health.”

Three other states — North Dakota, New Jersey, and Utah — have already banned the use of e-cigarettes in certain public places. In California, 122 cities and counties have similar bans. Advocates of electronic cigarettes, however, claim that evidence about the health risks of these devices is limited. They say vaping is an important step on the road to quitting traditional cigarettes.

“This report inappropriately paints this complex and important public health topic as a black and white issue,” said Gregory Conley, president of the e-cigarette advocacy group American Vaping Association, in a press release. “Despite the health officer’s false claims, there is ample evidence that vaping helps smokers quit and is far less hazardous than smoking.”

Despite advocates’ claims that electronic cigarettes are useful tools to help people wean themselves off of conventional cigarettes, support for that view is limited.

“There is no scientific evidence that e-cigarettes help smokers to successfully quit traditional cigarettes or that they reduce consumption of traditional cigarettes,” said the CDPH report.

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