Medical marijuana is becoming a big cash crop in Denver in light of a recent federal policy change, sprouting dozens of new businesses and hundreds of new customers every week.

But this growth is raising questions about how the substance should be regulated, whether there should be reasonable constraints on businesses that sell it, and if businesses and local governments should profit from the sales. They’re the same kinds of questions that have cropped up in California, as that state has even gone as far as debating legalization of marijuana and taxing it in a system similar to alcohol sales.

In Colorado, it hasn’t gone that far. But the surge in medical marijuana is sparking serious issues.

The medical-marijuana cottage industry has sparked serious concerns from employers on how to deal with workers who use the once-illicit drug. Many believe medical marijuana is being used illegitimately by people who want to get high—not just those who suffer from chronic pain and other symptoms.

“Right now, it’s the wild, wild West,” said Denver city councilman Charlie Brown, who’s proposing new laws for medical-marijuana dispensaries that operate in the city limits. “We don’t know where they’re located, and they don’t pay sales tax.”

The U.S. Department of Justice’s recent announcement that users and providers of medical marijuana won’t be prosecuted when they comply with state law has kindled interest in the drug as a business opportunity.

In Colorado, where voters approved a constitutional amendment allowing the use of medical marijuana in 2000, the DOJ’s announcement has fired up medical-marijuana dispensaries—establishments that cultivate and distribute marijuana for patients with certain medical conditions.

If advertisements in Westword, a popular alternative newspaper, are any indication, dozens of dispensaries are operating in the Denver area.

Andy Cookston, co-owner of Denver-based dispensary Cannabis Medical Technology, estimates there could be as many as 750 dispensaries in Colorado.

“It’s hard to say right now because there’s absolutely no regulation,” he said. While users of medical marijuana are required to register with the state, dispensaries aren’t licensed or obligated to report to the state.

More than 400 Coloradans a week are applying to Colorado’s Medical Marijuana Registry, said Mark Salley, a spokesman for the Colorado Department of Public Health and Environment. Salley said the registry is taking six to eight weeks to process applications because of the backlog.

To be certified as a medical-marijuana user, a patient needs a physician’s form stating why the patient needs to use the drug. The state’s medical-marijuana registry requires applicants to send the form and a photocopy of a valid ID.

As of July 1 (the latest date for which figures are available), the registry listed 11,094 certified medical-marijuana users taking cannabis to relieve chronic pain or symptoms of debilitating medical conditions.

Also known as “caretakers,” dispensaries can grow up to six plants per patient. Some operations serve as many as 1,000 customers.

The proliferation of medical marijuana in Colorado has its roots in the 2000 general election, when 54 percent of voters in the state approved Amendment 20, which allowed doctors to prescribe marijuana for certain medical uses, created a state-run registry of patients who can use medical marijuana, and allowed dispensaries to cultivate and sell marijuana on behalf of patients who don’t grow their own.

The amendment’s passage made Colorado the only state that authorized the use of medical marijuana in its constitution.

Though the amendment went into effect in 2001, few took it seriously because it conflicted with federal drug laws.

But some officials worry the lack of regulation, coupled with newly liberalized enforcement policies, could invite drug abuse in the state.