Nothing in the law allows for the invisible danger from “upset” emissions to persist, but legislation and reality often collide.

On the contrary, the federal Clean Air Act was meant to reduce harmful emissions by requiring continuous pollution limits for industrial facilities. But since its passage in 1970, state and federal regulators have created loopholes involving accidental releases — loopholes that have for years been challenged, re-written and bogged down in bureaucracy.

Nearly from the start, regulators began waiving pollution standards when equipment unexpectedly malfunctioned and had to be shut down, started up and maintained.

By 2004, 29 states had devised what University of Texas-Austin researcher Kelly Haragan calls “a flat-out exemption” for such emissions. The Environmental Protection Agency offered similar immunity for those involving hazardous air pollutants.

“There is a big caveat here,” acknowledges Adam Kushner, who headed the EPA’s air enforcement unit until last year. “They didn’t necessarily count against your compliance picture.”

This murkiness began fading after environmental groups sued the EPA in 2003, alleging its exemption violated clean-air laws. By December 2008, a federal court agreed, vacating the language. The agency has lagged at fully closing its loophole; earlier this year, it unveiled a proposed rule that would require facilities in any state to follow pollution limits during periods of start-up, shut down and maintenance.

For anyone anxious about toxic chemicals in the environment, Sunday marked a dubious milestone.

It has been three years since the “chemicals of concern” list landed at the White House Office of Management and Budget. The list, which the Environmental Protection Agency wants to put out for public comment, includes bisphenol A, a chemical used in polycarbonate plastic water bottles and other products; eight phthalates, which are used in flexible plastics; and certain flame-retardant compounds called polybrominated diphenyl ethers, or PBDEs.

The EPA wants to highlight these chemicals because “they may present an unreasonable risk to human health and/or the environment,” the agency says.

But any such listing must first be vetted by the OMB’s Office of Information and Regulatory Affairs, OIRA.

The EPA proposal arrived at OIRA on May 12, 2010. There it remains — a symbol, some say, of a broken regulatory system.

“It’s far past time for the OMB to conclude its review of the EPA’s proposal to list chemicals of concern,” Sen. Frank Lautenberg, D-N.J., said in a statement to the Center for Public Integrity. “Americans deserve access to information about the chemicals found in products throughout their homes that might pose a risk to their health.”

In a statement, OMB spokeswoman Ari Isaacman Astles wrote, “The Administration is committed to chemical safety and when it comes to complex safety rules, it is critical that we get them right.”

The Environmental Protection Agency announced new safeguards Friday to prevent conflicts of interest or bias from tainting its science, including efforts to assess the dangers of toxic chemicals.

The reforms, targeting scientific review panels selected for EPA by outside contractors, follow a Center for Public Integrity-PBS NewsHour examination revealing ties between scientists and industry on a panel reviewing hexavalent chromium, a compound commonly found in drinking water that may cause cancer.

In that case, three panelists who urged the EPA to delay potentially stricter drinking water standards had been expert witnesses for industry in hexavalent chromium litigation. The scientists denied any conflict and said their input was based on research, but the case study revealed how the EPA is unaware of potential conflicts on its own panels.

Under its own process, the Center reported, the agency turns over the job of selecting panelists to private companies, which handle conflict-of-interest reviews in secret. All information the vendors collect, including financial disclosure forms, is “considered private and non-disclosable to EPA or outside entities except as required by law,” the EPA policy says.

The changes announced Friday add more layers of review — and provide more public disclosure — to the process.

Environmental watchdogs, who had questioned EPA's existing process, say the steps are overdue.

“It brings transparency to a process that wasn’t there before,” said Francesca Grifo, a senior policy fellow and expert on scientific integrity at the Union of Concerned Scientists.

FALLS CHURCH, Va. — The woman who helped free an entire community from a toxic dump, literally rewriting environmental laws in the process, was so shy at the start of the struggle she tried to hide behind a tree when neighbors called on her.

Lois Gibbs took to the stage that day 35 years ago, in the seemingly idyllic community of Love Canal, N.Y., and began to find her voice. Transforming herself from homemaker to hell-raiser, she helped convince then-President Jimmy Carter to come to town in 1980 and remove 900 families from a 21,000-ton toxic dump. Earlier that year, Gibbs and her neighbors held two Environmental Protection Agency officials captive in a ploy to get the president’s attention. It worked.

Long before Erin Brockovich became a movie, Gibbs helped secure an environmental victory of greater heft. Love Canal’s war against the toxins under its feet prompted the federal government to create the Superfund cleanup program and earned Gibbs the Goldman Environmental Prize.

Today she is still in the fight as executive director of the Center for Health, Environment & Justice, a nonprofit squired in a third-floor corner office in a nondescript building in Fairfax County, Va., a few miles from Washington, D.C. A tiny gray sign hangs outside the door, betraying no sense of the history inside.

BELLE ROSE, La. — Tim Brown eases his john boat from his back yard dock into his daily therapy: The Bayou Corne that courses through this patch of southern Louisiana like a lifeline. Brown powers past the Tupelo Gum, Cypress Moss and Swamp Maple trees that drape the bayou in a frame, and steers to the spot where he reels catfish and collects thoughts.

“If I had to actually leave this place and go back to a house on dry land, I’d probably be dead in two years,” says Brown, 65 and retiring next year. “I guess you can say it’s a totally different life out here.”

But now that life, for Brown and 350 other residents in a neighborhood with “Crawfish Crossing” signs and roads named Gumbo, Jambalaya and Crawfish Stew Street, has been shattered by discovery of a 14-acre sinkhole that fractured the community’s calm and may bury its dreams.

The sinkhole, triggered by a collapsed cavern operated by salt mining operator Texas Brine Company LLC, swallowed trees and fouled the air when it appeared August 3. Its discovery sent the Bayou Corne community here in Belle Rose into a state of emergency: Assumption Parish and Louisiana officials ordered a still-in-effect evacuation as state officials scrambled to unearth what happened.

“Initially the concern was, that first day, you have a sinkhole … and you don’t know what caused it. All you know is a 400-by-400 section of marshland just got converted to a muddy pit. Trees were sinking into it and not coming back. It was like quicksand,” said Patrick Courreges, a spokesman for the Louisiana Department of Natural Resources.

HINKLEY, Calif. – Ten days before Christmas 1965, Pacific Gas & Electric Co. station chief Richard Jacobs walked a half-block on a dusty road lined with scraggly creosote shrubs to check out a neighbor’s toilet.

Jacobs carried with him a secret, something he referred to as the “chromate problem.”

Starting in 1952, the power company began mixing a toxic form of chromium with water to prevent rust at a new pipeline pumping station in Hinkley, a remote desert community united by a single school and a general store. PG&E dumped the chromium-laced water into a pond.

Lately there had been reports of problems with the neighbors’ wells. PG&E had just drawn greenish water from one well and discovered high levels of chromium. Now, retired farmer John Speth was complaining of greenish deposits in his toilet bowl.

Jacobs took a look in the bowl but assured Speth that PG&E had nothing to do with it. “When I left Mr. Speth,” Jacobs later wrote in longhand, “he was satisfied but still concerned about his water.” Speth died of stomach cancer in 1974.

It wasn’t until Dec. 7, 1987 — 22 years after that visit to Speth’s house — that PG&E finally told the local water board that it had contaminated the underground water. The company claimed it had discovered the problem just one week earlier.

From here, the story is familiar to anyone who saw the hit film Erin Brockovich. The corporate polluter was taken to court. The victims got millions of dollars. Problem solved.

In September 2010, scientists at the Environmental Protection Agency came to a startling conclusion: Even a small amount of a chemical compound commonly found in tap water may cause cancer.

The compound, hexavalent chromium, gained infamy in the Oscar-winning film Erin Brockovich, based on the David-vs.-Goliath legal duel between desert dwellers in Hinkley, Calif., and Pacific Gas & Electric Co. The film ends in Hollywood fashion, with the corporate polluter paying $333 million to people suffering from illnesses.

But in real life, the drama continues. More than 70 million Americans drink traces of chromium every day, according to the Environmental Working Group, a nonprofit research organization.

And now, more than a decade after the film, EPA scientists cite “clear evidence” that the chemical compound, also known as chromium (VI), can cause cancer. The federal agency was poised to announce its findings in 2011, a step almost certain to trigger stricter drinking-water standards to prevent new cancers and deaths.

The chemical industry’s trade association and chief lobbyist, the American Chemistry Council, urged the EPA to wait for more research, a common practice to delay action on toxic chemicals. However, Vincent Cogliano, the soft-spoken head of EPA’s chemical-assessment program, rebuffed the powerful group, writing in an April 2011 letter that “strong” new research was already available.