A new online poll finds about 10 percent of adults say they use e-cigarettes, the same percentage as in a similar poll last year. A growing number of adults have negative attitudes toward e-cigarettes, the Reuters/Ipsos poll found.

The poll of 9,766 adults found 47 percent said vaping is not healthier than smoking traditional cigarettes, compared with 38 percent last year.

This year, 43 percent of adults said they did not believe vaping can help people quit smoking, compared with 39 percent last year. The new poll found 66 percent said vaping can be addictive, while 61 percent held that view last year. Forty-nine percent this year said vaping could have a similar effect to secondhand tobacco smoke, compared with 42 percent in 2015.

Sales of e-cigarettes are expected to reach $4.1 billion this year, the article notes. Sales were down 6 percent in the first quarter of this year.

Some health experts note little is known about e-cigarettes’ potential health risks. They say they are concerned that teens who use the devices may become hooked on nicotine. Others say e-cigarettes are useful tools to help smokers quit.

In April, the Centers for Disease Control and Prevention released a report that found e-cigarettes are now the most widely used tobacco product among teens. E-cigarette use rose among middle school and high school students from 2011 to 2015, the report found.

Three million middle and high school students used e-cigarettes in 2015, an increase of 2.5 percent from the previous year. Among high school students, e-cigarette use rose from 1.5 percent to 16 percent, according to the report. Among middle school students, e-cigarette use increased from 0.6 percent to 5.3 percent during that period.

Earlier this month, the Food and Drug Administration announced it is extending its oversight to all tobacco products, including e-cigarettes. The agency will ban sales of e-cigarettes, cigars, pipe tobacco and hookah tobacco to people under age 18.