The CBD business came to Atlanta in force Friday, as what’s billed as the nation’s largest CBD and hemp convention opened.

From colorful gummy candy makers and vape pen vendors to equipment manufacturers, more than 270 vendors are expected at the convention, the USA CBD Expo at Georgia World Congress Center.

CBD is short for cannabidiol, a chemical that comes from marijuana and a sister plant, hemp. It’s not the chemical that makes people high. That’s THC, or tetrahydrocannabinol, and it’s not legal for recreational use in Georgia. Many CBD products contain tiny amounts of a type of THC, but stay below the legal threshold.

The CBD business is exploding in the United States, after Congress four years ago broadly legalized the farming of hemp. That approval came on the heels of scientific research, published in the British journal The Lancet, suggesting that CBD could reduce severe seizures in some epileptic patients.

The FDA hasn’t approved it as a medicine for anything else, yet the big business comes from other effects attributed to CBD.

Preliminary research has indicated that CBD can have a calming effect, ease anxiety, and help some forms of pain. A profusion of scientific papers on CBD has supported the notion of exploring CBD, but caution too little is known about it yet to draw conclusions. They also point to potential side effects, including harmful interactions with some drugs.

The customers aren’t waiting.

“We have clients that do millions of dollars a month on CBD,” said Eli Rubin, CEO of Best Rate and its sister company Greenway Payments. He estimates his clients process about $200 to $400 million in e-commerce payments for CBD products.

At the PipCBD booth bearing jars of CBD-infused body cream, lip balm, and “intimate oil,” Stephanie Bell sang the praises of the Atlanta market. Six Atlanta retailers carry her company’s products, including a chiropractor, CBD shops and an adult shop. Bell markets her wares as “premium, innovative and pure,” manufactured in Massachusetts from U.S.-grown hemp plants.

“What we found of Atlanta is it’s such a really good market for CBD,” she said. “People are really opening their minds here to the advantages of hemp.”

At the corner booth for Diamond CBD’s Delta 8 products, sales staff in dark business wear hawked a rainbow array of lollipops and gummy candies that sported 20 flavors, from fruit punch to pink lemonade to acai to orange creamsicle.

A few steps away, Futurola Amsterdam’s equally spacious corner booth was a contrast in modern: sales staff in blinding white slacks and blazers on white and silver steel furniture trod a white floor, selling the company’s joint rolling paper cones and automatic rolling machines. All with a video screen blaring music and showing Mike Tyson smoking. Tyson himself is expected at the company’s Las Vegas expo.

Futurola’s sleek designs market rolling papers — the cones — in sizes including “reefer,” “fatboy,” and the biggest, “party.” The fatboy and party sizes are bigger than the “king” size.

The papers come in boxes of up to 1,000, but that’s a fraction of what their wholesale clients order, cautioned account executive Brianne Tolp. “We have companies that buy 18 pallets of boxes,” she said. “Everyone from your small smoke shop to huge Canadian companies.”

Rubin, whose company helps other companies get set up with credit card companies to process payments in the high-risk business — risks of chargebacks and bad payments — said there’s something middle-of-the road about CBD that makes it palatable to more consumers.

“It’s a happy medium,” Rubin said, “Maybe like renting R movies instead of X movies.”