"Although e-cigs generally contain fewer toxicants than combustible tobacco products, they can expose users to harmful chemicals in addition to nicotine", he added.
But the industry's response wasn't enough to preempt the surgeon general from issuing its official nationwide warning Tuesday.
The US Surgeon General is alarmed by the increasing use of vapes by teenagers.
"You have an important role to play in addressing this public health epidemic", the advisory said.
The advisory was prompted by the latest statistics on vaping among youths, which found e-cigarette use among high school students has increased dramatically in the past year.
"These products also use nicotine salts, which allow particularly high levels of nicotine to be inhaled more easily and with less irritation than the free-base nicotine that has traditionally been used in tobacco products, including e-cigarettes", according to the surgeon general. He urged parents, teachers and health officials to make teens aware of the health risks. Health professionals should ask about e-cigarettes when screening patients for tobacco use, the advisory said.
More than half the nation-26 states-have enacted bans on smoking in enclosed workspaces, bars and restaurants. The flavors remain available via age-restricted online sales.
Adams singled out the e-cigarette product Juul for special condemnation because it appears to be highly popular with teenagers.
It is only the second public advisory by the surgeon general since he took the post 16 months ago. That correlation strongly suggests that young people who would otherwise be smoking are vaping instead, which represents a huge improvement in terms of health risks. "They don't realize the nicotine can interfere with their brain development, that the sweet flavors don't make the products any less unsafe", Ryan said.
"There is clear evidence that these products are not safe for our young people", said MD Anderson president Dr. Peter Pisters. Skidmore College in NY will ban all use of any cigarettes or e-cigarettes, anywhere on its campus, starting January 1.
In September, the U.S. Food and Drug Administration said it was mulling a ban on flavored e-cigarettes from makers including JUUL, Vuse and MarkTen XL, citing the threat of creating a new generation of nicotine addicts.
Tobacco use has plummeted in the USA but still remains the No. 1 cause of preventable deaths, mostly from heart disease, cancer and lung disease.