Ontario’s new health minister is holding off on approving three planned overdose prevention sites that would allow drug users to inject themselves under a nurse’s supervision.

Researchers and addiction experts say the sites save lives. For example, a study of a Vancouver safe-injection site that opened in 2003 found that it significantly reduced mortality and HIV infections.

But Ontario’s Progressive Conservative Health Minister Christine Elliott says she isn’t convinced.

“They're not as effective as some people think that they are,” she said while confirming she will review whether the sites have merit before deciding to allow them in Thunder Bay, St. Catharines and Toronto.

Elliott said she is also looking into concerns that people have raised about the impact of the injection sites on neighbourhoods.

CTV News found many concerns when it visited the Works, just off Yonge-Dundas Square in downtown Toronto near Ryerson University. The Works became the city’s first supervised-injection site last November, with support from former Liberal premier Kathleen Wynne and Toronto Mayor John Tory.

Mark Garner, from the Downtown Yonge Business Improvement Area, says the BIA has found more discarded needles in the first half of 2018 than in all of 2017. On Monday, he found a stash of five in a plant box outside a pub.

The BIA supports efforts to save lives, but businesses have paid a price. They’ve had to increase security, paid to clean up needles, and dealt with plumbing problems due to needles discarded in toilets, according to Garner.

“This is the number one tourist destination in Canada,” he said. “How do we integrate that into the neighbourhood, what resources are needed and how do we make it safe for everybody?” he said.

Igor Ponizoe, whose shop is near the site, has had to put up a sign asking men not to urinate on his doorstep. Every morning, he has to clean up garbage and drug debris.

“It just affects the whole energy in this area,” Ponizoe said. “It doesn’t make this area more attractive.”

But addiction expert Dennis Long said he believes reviewing the sites is “probably one of the stupidest moves I’ve heard in a long time.”

“We are in the middle of a crisis where people are dying,” he said.

Opposition Leader Andrea Horwath also supports the sites. "To suggest that somehow the evidence isn't there is wrong,” she said.

Public Health Canada says there were 3,987 apparent opioid-related deaths in Canada in 2017. More than 4,427 people visited emergency rooms in Ontario in 2016 for opioid-related overdoses, according to provincial statistics.

Elliott says her review will be complete by the end of September.

With a report from CTV Medical Correspondent Avis Favaro and files from The Canadian Press