BOSTON (AP) — Forty attorneys general, including Tennessee's Bob Cooper, sent a letter to the U.S. Food and Drug Administration on Tuesday urging the agency to meet its own deadline and regulate electronic cigarettes in the same way it regulates tobacco products.

The letter, co-sponsored by Massachusetts Attorney Martha Coakley and Ohio Attorney General Mike DeWine, says e-cigarettes are being marketed to children through cartoon-like advertising characters and by offering fruit and candy flavors, much like cigarettes were once marketed to hook new smokers.

At the same time, e-cigarettes are becoming more affordable and more widely available as the use of regular cigarettes decline as they become more expensive and less socially acceptable.

"Unlike traditional tobacco products, there are no federal age restrictions that would prevent children from obtaining e-cigarettes, nor are there any advertising restrictions," DeWine wrote.

Electronic cigarettes are metal or plastic battery-powered devices resembling traditional cigarettes that heat a liquid nicotine solution, creating vapor that users inhale. Users get nicotine without the chemicals, tar or odor of regular cigarettes.

E-cigarettes are being advertised during prime-time television hours at a time when many children are watching, according to the letter, which has led a surge in sales and use.

The health effects of e-cigarettes have not been adequately studied and the ingredients are not regulated, the letter said.

"People, especially kids, are being led to believe that e-cigarettes are a safe alternative, but they are highly addictive and can deliver strong doses of nicotine," Coakley said.

Citing a National Youth Tobacco Surveys conducted by the Centers for Disease Control and Prevention, the attorneys generals said 1.8 million middle and high school students said they had tried e-cigarettes in 2012, mirroring increases in the use of the product by adults.

The letter urges the FDA to meet an Oct. 31 deadline to issue proposed regulations that will address the advertising, ingredients and sale to minors of e-cigarettes. The decision has been delayed in the past.

Tom Kiklas, co-founder and chief financial officer of the industry group, the Tobacco Vapor Electronic Cigarette Association, agrees that e-cigarettes should be regulated as tobacco products. The group represents dozens of companies involved in the manufacture and sales of e-cigarettes.

"We're in agreement with responsible restrictions on the marketing and sales of these products," including a ban on marketing aimed at children, he said. "What I cringe at is when e-cigarettes get demonized."

The other states and territories joining the letter to the FDA, according to Coakley's office, are: Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Guam, Hawaii, Idaho, Illinois, Indiana, Iowa, Kentucky, Louisiana, Maine, Maryland, Michigan, Minnesota, Mississippi, Missouri, Montana, Nevada, New Hampshire, New Mexico, New York, North Carolina, Oregon, Pennsylvania, Puerto Rico, Rhode Island, South Dakota, Tennessee, Utah, Vermont, Virgin Islands, Washington, and Wyoming.