(This version of the story revises para 8 to indicate where the research institute is headquartered.)

Addicts regularly use drugs on the streets of San Francisco, and some people there say giving addicts a safe, clean place to shoot up – and clean needles – could help curb overdose deaths and diseases.

But critics object to enabling addicts to shoot illegal drugs in a supervised injection facility in San Francisco – or anywhere in the U.S.

A new cost-benefit analysis in the Journal of Drug Issues makes the financial case for a supervised injection site. A 13-booth facility in San Francisco could save $3.5 million a year, mostly in reduced medical costs, the report calculates.

The estimate assumes San Francisco would open a center exactly like Insite – North America’s first legal supervised drug-injection site built in Vancouver, Canada in 2003. Insite serves an estimated 1,700 people a month.

An injection facility in San Francisco would save the life of one drug user who would otherwise die of an overdose every four years and would assist in getting 110 drug addicts medication-assisted treatment each year, the new study suggests.

In addition, it would prevent an average of 19 cases of hepatitis C and three cases of HIV infection a year and would reduce hospital stays for skin and soft-tissue infections related to needle use by 415 days a year.

“To me, it’s really a win-win for everyone,” senior author Alex Kral said in a phone interview. “It’s a win for the community to get people off the streets, and it’s a win for the people injecting drugs to be sure they can be as safe as possible.”

An epidemiologist, Kral directs the behavioral and urban health program at RTI International, a nonprofit research institute with headquarters in Research Triangle Park, North Carolina.

Propelled by prescription painkiller and heroin abuse, U.S. deaths from drug overdoses hit a record 47,055 in 2014, according to the Centers for Disease Control and Prevention. The study authors estimate the U.S. spends more than $6 billion a year covering the medical expenses of people who inject drugs.

“This is one way to reduce what is one of the biggest sources of mortality in the country,” Kral said.

“We’ve tried a lot of things in the last 50 years, and none of them have succeeded,” he said. “So why not try an innovative, evidence-based solution that’s working in upwards of a dozen countries?”

Since the first supervised injection facility opened in the Swiss city of Berne in 1986, nearly 100 similar facilities have opened in 66 cities across 11 countries. U.S. cities from Seattle to New York have considered installing drug-injection sites, but none have been able to clear the hurdles.

Kral and his team assumed it would cost $2 million to buy and renovate a site for a supervised injection facility in San Francisco and $2.6 million a year to operate it. For every dollar spent, $2.33 would be saved as a result of averted overdose deaths, reduced disease transmission and increased drug treatment, the researchers found.

They expect the savings would be greater in other cities where the number of overdose deaths is higher and real estate and operating costs might be lower. San Francisco already slashed heroin overdose deaths from 120 to 13 a year between 2000 and 2012 largely because of widespread distribution of naloxone, a drug that can prevent overdoses by blocking the effects of opioids.

A supervised injection facility would likely bring more financial and life-saving benefits to a city like Baltimore, which has a higher percentage of needle users dying of heroin overdoses, the authors write.

Susan Sherman is working on a similar cost-benefit analysis for an injection facility in Baltimore. A professor of health, behavior and society at Johns Hopkins University in Baltimore, Sherman was not involved with the current study.

People fear supervised injection sites, she said, because they believe the facilities could draw drug users to their neighborhoods. But the sites would be located in areas where addicts already live.

“We have neighborhoods in Baltimore where heroin is the biggest economy,” she said in a phone interview. “Having a place to go and not being on a dirty street corner is foundational for dignity and respect, which can transfer into other aspects of their lives.”

“Having a safe consumption space somewhere in the U.S. is going to happen,” Sherman said. “It’s close to reality in New York, Ithaca and Seattle.”