TORONTO -- The chairman of Toronto's board of health says the province has notified health units across Ontario their funding will be cut immediately as the government makes changes to a cost-sharing arrangement with municipalities.

Joe Cressy -- who is also a Toronto city councillor -- says the cuts will mean Toronto Public Health will lose $1 billion in funding over the next decade and all of Ontario's health units will be impacted by the move.

The Ministry of Health delivered the news Thursday afternoon in a conference call with public health units ahead of the long weekend, he said.

Cressy said the long list of affected programs includes disease prevention, water quality testing, and immunization monitoring and surveillance.

"I say this without an ounce of exaggeration," he said. "Because of today's cuts people will die."

The province notified health units that it will reduce cost-sharing from levels from 100 per cent or 75 per cent in some cases, to 60 to 70 per cent for some municipalities, he said.

In Toronto's case, Cressy said the cost-sharing for some programs drops to 50-50 by 2021.

The changes mean Toronto will immediately have an $86 million funding gap in its public health budget this year, he said.

"What that means is that for our immunization monitoring and surveillance program, for our sexual health services programs, for our food safety regulatory initiatives, to our water quality testing, we don't know how we are going to continue to run those programs this year," he said.

Toronto Mayor John Tory condemned the funding cut in a statement late Thursday afternoon, saying while all health units will be impacted, the changes to Toronto are particularly punishing.

"It is impossible not to see this as a targeted attack on the health of our entire city and, in particular, the health of Toronto's most vulnerable people," he said. "It is inconceivable why the Ontario government would want to single out Toronto, Ontario's capital and economic engine, for harsher treatment when we know a healthy city is a prosperous city."

Tory said he intends to voice strong opposition to the cut and called on the province to back down.

"This is a dangerous way to curtail expenditures and we will be working hard with Toronto residents to see it reversed," he said.

Cressy said the changes mark a return to the cost-sharing between the province and municipalities that existed prior to the SARS and Walkerton E. coli outbreaks. In the wake of those events, the government beefed up funding to public health, he said.

"The evidence has shown that the more money you put in public health the fewer health care costs you have going forward," he said.

A spokeswoman for Minister of Health Christine Elliott said the government is working directly with municipalities as it shifts the cost-sharing model over the next three years.

"In an effort to fear monger and sow confusion, Joe Cressy is fundamentally misrepresenting the facts," Hayley Chazan said in a statement. "Here's the truth: our government is strengthening the role of municipalities in the delivery of public health."

Ontario's government has announced a number of funding cuts that it says will help deal with the province's $11.7-billion deficit.

NDP legislator Marit Stiles said Thursday the cuts are irresponsible.

"These are not areas where we can cut corners, this is crucial funding," she said. "The fact this information is leaking out late on Thursday evening before a long weekend, I think that is no coincidence. The government needs to come clean about these cuts."