Ohio River communities built around promises of economic opportunity and secluded riverside homes tucked in the hills house less than 6 percent of Ohio's residents.

Yet the factory-dotted land near the river produces a quarter of the state's toxic waste and 68 percent of its air pollutants, according to a newspaper analysis.

The Columbus Dispatch's study comes as the eight-state commission that oversees the river's water quality considers easing pollution restrictions to cope with aging sewer systems.

With river regulations divided among three federal regions and several state agencies in Ohio, Kentucky and West Virginia, nearby residents worry that officials aren't doing all they can to protect them from potential health hazards.

The air outside Alonzo Spencer's house in East Liverpool, Ohio, once smelled like cat urine. He said he believes the hazardous waste incinerator at the bottom of the hill is a health hazard.

Spencer said he fears an explosion at the Von Roll WTI incinerator - about 50 miles north of Wheeling, W. Va. - could release toxic gases into homes and schools.

‘‘When it happens - and it will - people will ask me what I did to prevent it,'' he said. ‘‘I will say, 'Everything I could.'''

Spencer has fought Von Roll since before the incinerator was built in 1992. It was touted as a job source for a town hurt by foreign competition in pottery and china manufacturing.

The U.S. Environmental Protection Agency slapped Von Roll with a $644,000 fine for dioxin emission levels recorded at 6.5 times the agency's limit in testing two years ago.

Von Roll environmental engineer Vince Waggle pointed out that the measurement came during an atypical operation - a test of the incinerator's emergency procedures. He said emissions during normal operations are well below standards.

‘‘As you walk around and talk to people, I'm sure you'd find a few who don't like us,'' spokesman Mike Parkes said. ‘‘But I'm also sure you'd find more people who feel we do a good job.''

Half an hour down the river, Mingo Junction residents say their town of about 3,500 across from Follansbee, W.Va., depends on the steel mill that employs about a third of the population.

‘‘People working in these plants are making a decent wage,'' said resident Joseph Mannarino, who worked for Wheeling-Pittsburgh Steel Corp. for 42 years. ‘‘If they shut down, we're done.''

Unions representing workers in riverside factories say pollution is not much of a concern while plants and mills struggle with foreign competition and rising costs. The companies say pollution controls are another factor that drives up company costs.

‘‘We compete with steel that gets produced in countries where they don't have the expense of pollution controls, where the wages and health benefits are not equal to what we pay,'' said Wheeling-Pittsburgh Steel spokesman Jim Kosowski.

State and federal regulators in the region have a tough job of enforcing pollution controls and often have to rely on companies to provide accurate information, Ohio EPA Director Joe Koncelik said.

Ohio has 70,000 sources of air pollutants and 1,200 EPA employees, he said.

‘‘It's impossible for us to get every single facility,'' Koncelik said.

Regulators also are slowed by overlapping oversight. The Ohio River spans three regions of U.S. EPA coverage and three state EPAs. State health departments and the federal Agency for Toxic Substances Disease Registry deal with health questions stemming from pollution, and the Ohio River Valley Water Sanitation Commission is responsible for water quality issues.

That commission has been dealing with how to handle runoff from old community sewer systems that spill untreated sewage when backed up with heavy rains. About 50 communities from Pennsylvania to Illinois have such systems.

The largest, Cincinnati, dumps about 6 billion gallons of untreated sewage each year. Two years ago, under pressure from a lawsuit filed by the Sierra Club, the city and Hamilton County agreed to fix the system by 2022 at a cost of at least $1 billion.