Joe Racanelli slung a sagging plastic bag onto a heap of others on the back of his garbage truck and leaned on two levers to close a set of steel jaws.

"Watch out. They spit," he warned as the mechanical maw chomped the wet bags, which burst with staccato pops. Juice, as he called it, oozed from the seams of the truck. "This is the part I hate most -- the messy part," said Racanelli, 40.

The 12-year veteran garbage collector, part of a recycling effort, was helping to quiet the trash talk across the U.S.-Canadian border. A long-simmering feud over what to do with Toronto's garbage was enflamed last week by Democratic presidential candidate John F. Kerry, who promised Michigan residents that he would stop garbage trucked south from Canada into the state. "It's time to end the Canadian trash-dumping in Michigan," Kerry said. His remarks have incensed people in Toronto.

Kerry has become "the front-runner to be the most anti-Canadian candidate," huffed Don Martin, a columnist for the National Post newspaper. Kerry was probably "just seeking votes," said an editorial in the Toronto Star, but his stance "is generating new hostilities from Americans."

Toronto's umbrage comes in part because local officials contend that their trash is better than garbage from Michigan and most other cities. Toronto's rate of recycling paper and plastic is on par with efforts in other big cities, and the wet garbage that Racanelli threw onto his truck was part of an ambitious program of collecting organic kitchen waste separately to be eaten by microbes and returned to the soil.

"By this time next year, we will be the best city in North America at diverting waste," said Gord Perks, a senior campaigner at the Toronto Environmental Alliance, an advocacy group.

"We're doing everything reasonably in our power to reduce our solid waste going to Michigan," Toronto Mayor David Miller said in an interview.

"The material we are sending there is as safe or safer than the stuff local people there are putting in their landfills," said the chief of solid waste for the city, Angelos Bacopoulos.

But if the garbage is so clean, why don't they keep it in Ontario? ask Americans on the other side of the border.

"You should listen to the noise and smell the stench and see the dangerous road conditions that we have to deal with every day," said Lynette Guzman, who lives with her husband and two children in Wayne County, Mich. Most of the 140 trucks coming from Toronto each day exit Interstate 275 a mile from her home and barrel past on their way to the Carleton Farms Landfill, another mile down the road, she said.

The United States and Canada have a free-trade agreement that nearly erases the border for commerce. The U.S. Supreme Court has repeatedly ruled that garbage is a commodity to be treated like any other commercial product.

So in 2002, when mounting political pressure forced Ontario to close Toronto's largest landfill, a garbage-handling firm, Republic Services of Florida, offered to ship the city's trash to its landfill in Sumpter Township, Mich., a rural area 25 miles southwest of Detroit. The price for removing the trash was $40 million a year, more than twice what the city was spending.

It was hardly a novel arrangement for Michigan, which receives trash from seven states ranging from neighbors Indiana and Illinois to New Jersey, as well as municipal trash from elsewhere in Ontario. The business is a growing political issue within Michigan, led by those concerned that the state has become a dumping ground.

"We want space in Michigan restricted to Michigan trash," said Mike Garfield, director of the Ecology Center, an environmental activist group in Michigan. "We have brought this problem on ourselves. We have an oversupply of landfills and lower tipping fees. "

But it's a two-way street. A Massachusetts-based company, Clean Harbors Environmental Services, operates a hazardous-waste landfill and incinerator in Ontario that receives about 132,000 tons each year of contaminated sludge, foundry sands, old solvents and heavy metals from the United States, primarily from auto manufacturing plants around the Great Lakes, according to an official of the company, Phillip Retallick. The trucks pass each other at the border separating Ontario from Michigan.

The garbage that goes to Michigan seems pretty sweet to the Sumpter Township government. It took in $3.5 million this year in fees from Republic Services, about 40 percent of its budget, said Dwayne Seals, the township's financial officer.

"That revenue stream has kept taxes from going up," said Tim Hicks, a member of the township's Board of Trustees. "We didn't ask for the landfill. It was forced down our throats 10 years ago. But it's there. It's going to be used until it is filled. And we are going to milk it for every penny."

Hicks is annoyed that others in Michigan, led by U.S. Sen. Debbie Stabenow, a Democrat, and Jennifer M. Granholm, Michigan's Canadian-born governor, have led the opposition to the import of Canadian trash. Democratic vice presidential candidate John Edwards jumped in at a Labor Day speech in Kalamazoo, complaining that President Bush "will allow Canadian trash into this country but won't allow the importation of prescription drugs from Canada."

Kerry joined the charge the next day. "George W. Bush has let Michigan become Canada's landfill," he said in a statement.

Toronto could face a catastrophe if the United States blocked access, with trash piling up on the streets within days, city officials said. But they doubt Kerry would have the authority to do it. "I don't think they could shut it down, but they could make it extremely difficult to move the trucks across" through zealous inspections and myriad rules, Bacopoulos acknowledged.

But he said the objections ignore the progress. The garbage shipments to Michigan -- 1.5 million tons last year -- have peaked and will drop each year, reaching zero by 2010, he said.

A big portion of that reduction involves new technology like that at Toronto's Vanley Transfer Station. There, the organic waste -- mostly wet garbage collected in special green bins from residences and businesses in Toronto -- is ground and mixed with water into a smelly soup, then piped into a five-story vat where microbes feed on the stuff for two weeks.

Then the water is squeezed out, and the resulting sludge is taken by tractor to a nearby field, where a farmer turns it over for eight months and sells it as part of landscaping soil.

Bacopoulos -- who said that in 22 years of dealing with waste disposal issues he has had everything from dead fish to earmuffs thrown at him by angry residents -- remains puzzled at the reaction to trash.

"Nobody objects when trucks carry loads of shoes and cabbage and clothes," he mused. "But then when we take that stuff, use it, and put it on a truck to go to a landfill, people start yelling that it's going to kill us."

In Toronto, Joe Racanelli hoists a bin of organic kitchen waste into his garbage truck. The waste will be turned into soil, reducing the amount of trash headed to a Michigan landfill.Toronto says efforts like its Green Bin Program make its trash better than the refuse produced in Michigan.