Feb. 24, 2011  -- Oil industry documents filed with the federal government reveal that an accidental release of a lethal chemical used in 50 aging refineries across the country could prove devastating, with 16 million Americans living within range of toxic plumes that could spread for miles.

Los Angeles, Philadelphia, Minneapolis, New Orleans, and the stretch of Texas coastline known as "Refinery Row" are among the at-risk areas cited in the documents. Citing homeland security concerns, the government keeps the industry filings under close guard in Washington, D.C. They were reviewed as part of a joint investigation by ABC News and the Center for Public Integrity that airs tonight on World News with Diane Sawyer and Nightline.

CLICK HERE to read the Center for Public Integrity's story on oil refineries.

There are safer alternatives for the chemical hydrofluoric acid, which is used to make high-grade gasoline, but the industry has resisted calls to stop using it. An industry spokesman told ABC News it would not be feasible to retrofit the refineries to use the safer approach. Federal officials tell ABC News, however, that the real impediment may be money-- estimating it would cost about $50 million for the companies to upgrade each plant.

According to the industry's worst-case scenario documents, a release of the chemical could endanger entire communities.

"Hydrofluoric acid is extremely toxic," said Sen. Patty Murray, D-Washington. "It can be deadly immediately to workers around them, it can affect an entire community."

Murray called the plants "a ticking time bomb."

CLICK HERE for a slideshow about aging oil refineries in America.

Even though one-third of the oil refineries in the United States are using the chemical, Murray told ABC News that the industry has long avoided demands from safety advocates and from the union that represents refinery workers that it explore safer options.

CLICK HERE to learn what you can do if toxic gas escapes from your local oil refinery.

"For three hours of revenue an oil company can change the use of hydrofluoric acid to make it safer for the workers and the community," Murray said. "Certainly that kind of investment assures people are safe when they go to work and the communities, the people who live around those refineries, are protected. It's worth it."

Accident at Philadelphia Sunoco Refinery

Industry officials downplayed the risk of a large-scale chemical release as remote. Charles Drevna, president of the National Petrochemical and Refiners Association, told ABC News that over the 70 years the chemical has been in use, "there hasn't been any [hydrofluoric acid] released that has impacted the communities. We've controlled them."

Drevna spoke at length with ABC News, and repeatedly emphasized the industry's commitment to safety. "I think our safety record could be improved," Drevna said. "But it's not a bad safety record."

Officials at the U.S. Chemical Safety Board, however, have warned that while the refinery industry has been painting a rosy picture of the conditions at their facilities, it has compiled a disconcerting track record. As the nation's 150 refineries have aged, there have been an increasing number of fatal, or near-fatal, incidents. In the last two years alone, there have been 29 fires and explosions at refineries that use the deadly chemical, including at least three potentially dangerous releases of hydrofluoric acid. And 32 refineries that use hydrofluoric acid have amassed more than 1,000 willful, serious or repeat safety violations in the last five years.

CLICK HERE to watch a giant hydrofluoric acid cloud form.

In 2009, an accident at the Sunoco refinery in Philadelphia caused a hydrofluoric acid release. James Jamison, an ironworker who was working on the acid unit at the time, described to ABC News how he became engulfed in a cloud of the noxious chemical. "It seemed like a rain cloud, and the smell was so intense I could feel it through my eyes, my nose, it was like a heat wave came over me."

CLICK HERE to watch an interview with James Jamison.

Sunoco disputes Jamison's claim that he suffered permanent lung and heart damage in the accident, and the two parties are now in court. Federal investigators found that the company had failed to address leaks in the acid storage unit that had been a recurring problem for decades. In a statement to ABC News, Sunoco said it has since invested $200 million in improving the safety and reliability of the equipment involved in the use and storage of hydrofluoric acid, "state-of-the-art technology" that it says will help avoid another accident.

Corpus Christi Citgo Oil Refinery Explosion

In most places where refineries are running, the surrounding communities are unaware of the risks associated with hydrofluoric acid. But in Corpus Christi, Texas, the fears are as palpable as the warning sirens that come at all times of the day and night.

Citgo says it tests alarms daily, and encourages employees to sound the alarm if they think something has gone awry. "While this approach can result in false alarms, CITGO would rather sound the alarm and not need it, than not sound it if we need to," the company said in a statement.

Few have forgotten what happened the last time, less than two years ago, when something significant did go awry. An explosion at the Citgo refinery released a cloud of hydrofluoric acid that just missed the neighborhood. Citgo said in a statement that the fire and gas leak were contained, and never reached the surrounding community. But a subsequent investigation by the U.S. Chemical Safety Board found that water systems meant to contain a leak didn't entirely succeed.

Residents of Corpus Christi have tried to learn to live with the risk – some packing bags of clothes by their beds so they can make a quick escape if the plant erupts.

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Janie Mumphord, who lives just a few blocks from the refinery, said she fears the worst. "You never know when you go to bed if you're gonna live through the night, or if you have to run through the night," she said.

The Center for Public Integrity is a nonprofit, investigative reporting outlet in Washington, D.C.

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