The businesses included a handful of growers and sellers, but most offered services many might not think about when considering the marijuana trade.

“We saw an opportunity,” explained Jody Goyette, program manager at Creative Service Inc.

The Mansfield-based company, which provides background tests, operated for nearly 40 years before tapping into the marijuana market in 2013.

Today, Creative Service does a fair amount of business in the industry, contracting with the state along with private firms to run background tests on individuals and companies. The business is poised to grow, as more marijuana companies receive licenses from the state and will be required to run yearly background checks on all employees in accordance with state law.

Creative Services is not alone. At least 11 Massachusetts-based companies at the expo offered services besides growing and selling cannabis products, including American Alarm in Arlington, which provides security systems. Griffin Greenhouse Supplies in Tewksbury sells greenhouse equipment. Matter Communications in Newburyport is a public relations firm, and Neo-Advent Technologies LLC in Littleton is a pharmaceutical research and development firm.

“It’s similar to pharmaceuticals,” said Michael Dellogono, who does business development for Kanabolytix, a cannabis-testing subsidiary of Toxikon in Bedford.

Toxikon, which currently tests pharmaceuticals, has applied for a license through Kanabolytix to test medical marijuana. If approved, Dellogono said the company would become the largest medical testing facility in the state. Dellogono didn’t know of any immediate plans to tap into the recreational market, but taking the step from pharmaceuticals to cannabis made a lot of sense from a business point of view, he added.

“We see it as an opportunity to put people at ease because they will know everything is being tested properly,” Dellogono said.