New York researchers say certain flavors and higher voltages significantly boost the toxicity of electronic cigarettes.

In a study published online Monday by the journal Tobacco Control, researchers at the Roswell Park Cancer Institute studied tobacco, pina colada, menthol, coffee and strawberry flavors, with strawberry turning out to be most toxic.

“Although many of the flavorings used in e-cigarette liquids have been certified as safe for eating, little is known about their effects when heated and inhaled in e-cigarettes,” senior author Maciej Goniewicz, assistant professor of oncology in the Department of Health Behavior at Roswell Park, said in a press release. “This study suggests that various characteristics of e-cigarettes, including any flavorings, may induce inhalation toxicity, and, therefore, caution should be used with these products until more comprehensive studies are performed.”

The researchers studied bronchial cells exposed to aerosol from variable-voltage e-cigarettes.

“Our study demonstrates that e-cigarette products differ significantly in the degree of their cellular toxicity to bronchial epithelial cells,” Goniewicz said.

He suggested e-cigarette users use less toxic flavors and set their devices at lower voltages to reduce potential harm.

Goniewicz said the findings have public health and regulatory implications. The Food and Drug Administration issued a series of regulations last month involving batteries, circuit boards and wires, as well as some flavors, that will eliminate 99 percent of the vapor products on the market within two years, said Tony Abboud of the Vapor Technology Association. The regulations make it impossible for any company to make alterations to its products without FDA approval, he said in a blog post on the Hill website.

The barriers are being adopted despite evidence e-cigarettes help people quit smoking. Researchers at University College London found the devices helped 18,000 people in England give up tobacco.

E-cigarettes are being treated like tobacco products in British Columbia, banned from workplaces, in parks and on beaches in a bid to protect youths “from the unknown effects of e-cigarette vapor and from becoming addicted to nicotine,” the provincial government said.

Goniewicz’s research was funded by the National Institute on Drug Abuse and the National Cancer Institute. Goniewicz also reported he received grants from pharmaceutical companies that manufacture smoking cessation drugs and has served on advisory boards for some of these companies.