MONDAY, Jan. 9, 2017 (HealthDay News) -- Fewer people now view e-cigarettes, which convert a nicotine liquid into vapor that's inhaled, as a less dangerous or healthier alternative to cigarettes, new research finds.

Public perception about these battery-operated devices is changing, even though studies investigating their health effects have had mixed results, the researchers said.

"It's a good thing that information about e-cigarettes' possible adverse health effects has gotten out there, especially considering there wasn't a government or public health push during the study years," said the study's leader, Eric Ford. He is a professor in the department of health policy and management at the Johns Hopkins Bloomberg School of Public Health in Baltimore.

"When misinformation about health effects about any substances becomes widespread, it is usually very hard to reverse the trend. That somehow happened here," Ford said in a university news release.

For the study, the researchers reviewed nationally representative surveys conducted in 2012, 2013 and 2014. The surveys -- sponsored by the U.S. National Cancer Institute -- included more than 3,000 smokers, former smokers and non-smokers each year.

Awareness of e-cigarettes increased about 17 percent between 2012 and 2014 (from 77 percent to 94 percent), the findings showed.

The study authors said that this greater awareness had no influence on smokers' intentions or attempts to kick the habit.

The surveys revealed that 50 percent of the people polled in 2012 believed e-cigarettes were not as harmful as cigarettes. Two years later, that number fell to 43 percent.

During this time period, e-cigarettes were marketed as a safer alternative to smoking traditional cigarettes because they don't contain tobacco, the study authors said.

Ford's team pointed out that many health experts worry that e-cigarettes could lead more people to start smoking cigarettes, the leading cause of preventable death around the world. Teens may be especially vulnerable to e-cigarette marketing, which could put them on the path to addiction with tobacco cigarettes, experts say.

As of 2014, e-cigarettes were used by nearly 4 percent of U.S. adults, particularly those who were current smokers or had quit within the past year, according to the U.S. Centers for Disease Control and Prevention.

The health effects of e-cigarettes remain unclear, the researchers cautioned. The products with flavoring and other ingredients that contain a chemical called diacetyl may be linked with lung conditions, such as bronchiolitis obliterans, or "popcorn lung." This causes scarring in the lungs that leads to the thickening and narrowing of the airways, the study authors said.

The U.S. Food and Drug Administration has revealed plans to start regulating e-cigarettes. Selling these products to anyone younger than 18 years of age will be prohibited. Recently, the U.S. Surgeon General also warned young people to avoid e-cigarettes entirely, calling them "unsafe."

The FDA has also said it will hold a two-day workshop in April to examine the dangers of exploding batteries in e-cigarettes.

The agency identified 66 instances of e-cigarette explosions in 2015 and early 2016, according to published reports. The batteries overheated, caught fire or blew up, sometimes causing severe injuries.

The new study was published online recently in the American Journal of Preventive Medicine.

More information

The U.S. National Institute on Drug Abuse has more about e-cigarettes.