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Early Data in E-Cigarette Study May Raise Safety Concerns
2015-01-09:     

A laboratory study presented early this year reported that the nicotine-laced vapor generated by an electronic cigarette promoted the development of cancer in certain types of human cells much in the same way that tobacco smoke does.


Researchers involved in the little-noticed study emphasized that their findings were preliminary and that the study did not involve people but specially treated human lung cells. Many researchers have expressed the belief that e-cigarettes pose a far lower cancer risk than conventional cigarettes because they do not burn tobacco, a major source of carcinogens.


However, the findings, which were presented in January at a meeting of lung cancer researchers, may attract the interest of federal officials who are considering how to regulate e-cigarettes. In a report to investors sent Tuesday, David J. Adelman, an industry analyst at Morgan Stanley, said the report, while preliminary, could “result in legitimate questions from public health officials.”


The study involved scientists from Boston University, the University of Texas Southwestern Medical Center in Dallas and the University of California, Los Angeles and was funded by the National Institutes of Health.


The Food and Drug Administration, which has oversight over tobacco, is expected to soon issue rules laying out a framework under which e-cigarettes will be regulated. Hundreds of e-cigarette brands are on the market, some of them made by major companies and others made by mom-and-pop shops.


In the study, researchers modified human lung cells to have specific genetic mutations that are associated with an increased risk for cancer. They then grew the cells in a liquid medium exposed for four hours to the vapor generated by an e-cigarette. Similarly treated cells were grown in a medium exposed to tobacco smoke.


The scientists reported that the cells exposed to e-cigarette vapor, like those exposed to tobacco smoke, exhibited changes associated with cancer.

Dr. Steven M. Dubinett, a professor at U.C.L.A. who led the study, emphasized in a telephone interview that the study’s findings were preliminary and did not establish a link between e-cigarettes and cancer. He added that the findings did underscore, however, how little is known about long-term effects of e-cigarette use or the specific effects of ingredients within the devices.


“There is a lot that we don’t know about e-cigarettes, and one concern is that some of the substances within e-cigarettes could contribute to negative health effects,” Dr. Dubinett said.

He added that it was not clear which ingredient or ingredients in the e-cigarette tested were responsible for causing the cellular changes.


Dr. Neal L. Benowitz, a leading nicotine researcher at the University of California, San Francisco, said it was hard to apply the findings of test-tube studies to people.


“Isolated cell systems may respond differently than organs in a person,” he said.


While e-cigarette vapor damaged human lung cells that were not modified to have the cancer-related mutations, it did not produce reactions in them associated with cancer, researchers reported. Such mutations, however, are found in some people who are smokers or who have stopped smoking.


Dr. Dubinett added that researchers were collecting additional data before submitting the findings to a medical journal for publication.


Clinical trials involving users of e-cigarettes are underway to determine what, if any, genetic changes occur in the tissue lining their lungs. Those studies are expected to continue for another year, Dr. Dubinett said.

Producers of e-cigarettes, including some major cigarette makers, are also conducting clinical trials in an effort to quantify their products’ health risks, particularly in contrast to those of conventional cigarettes.


Asked for a response, David M. Sylvia, a spokesman for the tobacco company Altria, parent company of Philip Morris USA, said in a statement: “Given that only an abstract of the study has been released, which contains limited information, we are unable to comment” on the study’s findings.


R. J. Reynolds did not respond to a request for comment, and a spokesman for Njoy, an e-cigarette company, said officials were not available Tuesday to comment.


A version of this article appears in print on April 16, 2014, on page B1 of the New York edition with the headline: E-Cigarette Study Data May Raise Concerns. Order Reprints|Today's Paper|Subscribe