They can look like nondescript writing pens or asthma inhalers. Some resemble lip-gloss sticks and come in the same hot pink or sparkly purple as teenage girls’ smartphone cases.

Others are bullet-like cylinders hanging on fat gold neck chains like gangsta bling. Some come boxed in a rainbow of neon colors looking a lot like marking pens.

Portable pot vaporizers — called “vapes” or “pocket hookahs” by users — are going hand-in-hand with the proliferation of electronic cigarettes and taking the marijuana world by storm. They are so well disguised and can be used so clandestinely that they are setting off alarm bells with those concerned about keeping legalized pot out of the hands of minors.

“This is incredibly concerning,” said Bob Doyle, executive director of the Colorado Tobacco Education and Prevention Alliance. “The marijuana vaporizing industry is as advanced or more advanced than the e-cigarette industry. The products are appealing to kids, and they promote the ability to hide marijuana use.”

That is “absurd,” said Mason Tvert, co-founder of Safer Alternative for Enjoyable Recreation. He said the vaporizers have been developed as a safer way for adults to consume marijuana without smoking it and without creating secondhand smoke.

“These products are not made, marketed or sold for kids,” Tvert said.

A 31-year-old hardcore athlete and regular user of a pocket vaporizer, who asked that his name not be used, said he agrees with Tvert’s assertion that vaporizers are meant as a safer alternative to smoking pot.

“I do it because it is more healthy,” he said.

And more easy to disguise, he added.

“If you have ever tried to smoke on a chairlift while skiing, you can appreciate a good hand-held vaporizer. They draw little attention, are fairly odorless and work despite gale-force winds,” he said.

The pocket vaporizers are made up of an atomizer and a battery unit that acts as a heater to create a breathable vapor. The batteries are charged with small wall plug-ins.

The fact that the vaporizers are tiny electronic devices with chargers like those used for other popular electronic devices prompted Rolling Stone magazine, in its June issue, to refer to them as “the iPod of getting baked.”

The chambers of the vaporizers can be filled with nonpsychoactive dried herbs or flavored oils that come with or without nicotine. Pot users fill vaporizers with dried weed or with butter, waxes or oils that have been processed from marijuana using chemicals such as butane to extract highly concentrated psychoactive THC.

“There is serious potency in these,” said Doyle.

There are thousands of brands of the devices, with names such as Trippy Stix, Vapbong, E-Buzz. RemPen and Puffit-X. Owners of shops selling the devices say new ones turn up daily and that the technology in the vaporizers is rapidly advancing.

“They came on the market a couple years ago, and they’ve really picked up steam. It seems like everybody and their brother are selling these,” said Michael Mahaney, whose wife owns the Headed West head shop in Englewood.

Mahaney stressed he does not sell to minors, but he acknowledged that vapes are getting into the hands of youths, like many other illicit things. The devices are easily available online

“Kids are going to get whatever they want,” he said.

Doyle said that as he travels around the state talking to various agencies and groups about the dangers of e-cigarettes — and now marijuana vaporizers — he has heard from high schoolers that the tiny, odorless devices are being widely used, sometimes even on campus.

Jamie Erb, manager of the Discontent head shop in Grand Junction, said there is a strong market for vaporizers among the college-aged crowd.

“The smaller the better right now,” she said, as 20-something shoppers ignored a large display of pipes in her shop and made a beeline for the locked cases of vaporizers.

There are no statistics about the specific use of vaporizers by minors, but Doyle points to the latest figures from the Colorado Division of Behavioral Health’s Healthy Kids Colorado Survey, which show that in the previous 30 days, 23 to 32 percent of high school-aged students said they had smoked marijuana and 12 to 17 percent said they had smoked cigarettes. The percentage of use went up with each higher grade level.

Nancy Lofholm: 970-256-1957, nlofholm@denverpost.com or twitter.com/nlofholm