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A UCLA study released this week suggests that e-cigarettes may not be significantly safer than tobacco cigarettes.

The research, which was conducted on cultured cells, found that e-cigarettes contain toxic substances and nanoparticles that could kill the top layer of skin cells in the oral cavity.

The research team led by Dr. Shen Hu, an associate professor of oral biology and medicine at the UCLA School of Dentistry, believe similar results could happen in a human study and that e-cigarettes could increase users’ risk for oral disease.

The researchers said their findings, published online in the journal PLOS One, also suggest that health care providers should do more to raise public awareness of the products’ health risks.

They noted that use of e-cigarettes has increased dramatically in the past few years, particularly among women and young people, and that health agencies in some nations, including the United Kingdom, have recommended e-cigarettes as a tobacco-cessation product.

The effects of conventional cigarette smoke on human health have been well documented, but Hu said there has been much less research on the health risks of e-cigarettes, particularly their effect on the oral cavity — the portion of the mouth behind the teeth and gums.

His team took cell cultures from the outermost layer of the oral cavity and exposed the cells to two different brands of e-cigarette vapor for 24 hours.

The vapor, containing varying amounts of nicotine or menthol, was generated by a machine built to “smoke” cigarettes like a human would. The researchers then measured the particle concentration and size distribution of the simulated vapors.

They found that e-cigarette vapors, which contain nanoparticles of metal, silica and carbon, vary in concentration depending on the e-cigarette brand and flavor.

Hu said laboratory tests on cultured cell lines showed that e-cigarette vapors may significantly weaken the oral cavity’s natural defense mechanism by decreasing the levels of an antioxidant called glutathione.

He said his team will next translate its findings to a human study.

“A small but significant portion of dental patients at UCLA Dental Clinics have used e-cigarettes, which will provide sufficient patient resources for our planned studies,” Hu said. “Our hope is to develop a screening model to help predict toxicity levels of e-cigarette products, so that consumers are better informed.”