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.

The Texas fertilizer plant that blew up on April 17, killing at least 15 people, appears to have been claiming an arcane exemption that allowed it to avoid targeted workplace inspections and safety requirements and enter a “streamlined prevention program” with environmental regulators, a government spokesman confirmed.

The owner of the facility near Waco, West Chemical and Fertilizer, apparently determined that the exemption — a few words advocated by industry groups, including The Fertilizer Institute, as part of a 20-year-old regulation — applied. In the wake of the deadly blast in West, Texas, last month, the Occupational Safety and Health Administration is investigating whether this claim was justified, an OSHA spokesman said.

By claiming the exemption, the company became subject to other, less stringent requirements and avoided certain OSHA and Environmental Protection Agency rules.

West Chemical and Fertilizer did not respond to requests for comment.

The interlocking web of company-claimed exceptions has implications beyond a small town in Central Texas. Sites across a host of industries housing large amounts of dangerous chemicals could claim they sell primarily to end users and avoid stricter regulation, though the number of facilities invoking this exemption is unclear. A representative for a company storing toxic chlorine gas, for example, wrote to OSHA in 2005 to clarify that the exemption applied to the site.

“It’s a major flaw,” said Bryan Haywood, an Ohio consultant who advises companies on the safe use of dangerous substances. “This incident’s going to get a lot of people’s interest into how people are squirming out of [stricter requirements].”

Federal regulators today announced new measures to protect 2.5 million temporary workers in America amid evidence such laborers are hurt more often than regular employees.

In December, the Center for Public Integrity and WBEZ/Chicago Public Media highlighted the case of temporary worker Carlos Centeno, who was badly burned in a Chicago-area factory in November 2011 and died three weeks later. Occupational Safety and Health Administration records obtained by the Center concluded that Centeno’s bosses refused to call 911 as his skin peeled and he screamed for help.

OSHA said today it had sent a memo to regional administrators “directing field inspectors to assess whether employers who use temporary workers are complying with their responsibilities” under the law.

“Inspectors will use a newly created code in their information system to denote when temporary workers are exposed to safety and health violations,” the agency said in a press release. “Additionally, they will assess whether temporary workers received required training in a language and vocabulary they could understand.”

As the Center/WBEZ story noted, recent research indicates temporary workers are more prone to injury than permanent ones due to often-subpar safety training and the feeling among some employers that temps are expendable. Last year, for example, researchers who studied nearly 4,000 amputations among workers in Illinois found that five of the 10 employers with the highest number of incidents were temporary staffing agencies.

As investigators unravel what caused a Texas fertilizer plant explosion last week that killed 14, the U.S. Bureau of Labor Statistics reported today that 4,693 workers died on the job in 2011, three more than in 2010.

The fatal injury rate for 2011, the most recent year with complete data, was 3.5 deaths per 100,000 full-time equivalent workers. That is down slightly from 2010.

According to the BLS, 1,937 workers died in transportation incidents; 710 through “contact with objects and equipment”; 681 from “falls, slips [and] trips”; and 419 from “exposure to harmful substances or environments.”

“The Texas plant explosion is the kind of catastrophe that really grabs the public’s attention,” said Tom O’Connor, executive director of the National Council for Occupational Safety and Health, an umbrella organization for a network of nonprofit groups around the country. “But that’s about the same number of people who die every day in the U.S., in ways that are much quieter and hidden from public view.”

On average, 13 workers a day are killed on the job in the United States and many more are injured. On April 17, the same day the fertilizer plant blew up in West, Texas, a dozen contract workers  were injured when a fire broke out at the ExxonMobil refinery in Beaumont, about 300 miles to the southeast; seven suffered severe burns.

This year, for the first time, the BLS fatality report has a separate category for contract workers, who may not be afforded the same protections as regular employees. Five hundred forty-two died in 2011, the bureau found, accounting for 12 percent of all fatal injuries. Texas had the highest number of contractor deaths – 56 – followed by Florida (51) and California (42).

Today marks the 43^rd anniversary of Earth Day, an invention of Gaylord Nelson — then a senator from Wisconsin — that triggered the environmental movement.

Back in 1970, as the Earth Day Network notes, “Americans were slurping leaded gas through massive V8 sedans. Industry belched out smoke and sludge with little fear of legal consequences or bad press. Air pollution was commonly accepted as the smell of prosperity.”

Today, as officials with the Environmental Protection Agency are quick to point out, things are better. An EPA study predicts, for instance, that 1990 amendments to the Clean Air Act will prevent some 230,000 premature deaths by 2020. In a speech last year, then-EPA Administrator Lisa Jackson said the Clean Water Act “has kept tens of billions of pounds of sewage, chemicals and trash out of our waterways.”

Like many, the Fertilizer Institute, a trade group, has extended its condolences to the people of West, Texas, where a blast at a fertilizer plant Wednesday evening killed at least a dozen and injured about 200.

The Washington-based institute, however, has lobbied against legislation that would require high-risk chemical facilities – including some of its members – to consider using safer substances and processes to lower the risk of catastrophic accidents and make such facilities less inviting to terrorists.

Senate records show that the institute has spent $7.4 million on lobbying since 2006, some of it in opposition to legislation like a 2009 bill that passed the House but never became law.

A spokeswoman for the institute did not respond to requests for comment Friday from the Center for Public Integrity. The organization says on its website that it supports existing rules enforced by the Department of Homeland Security and opposes any expansion of the rules “to mandate inherently safer technologies.”

In a 2011 letter to the chairman and ranking member of the House Homeland Security Committee, the institute and nine other groups maintained that “America’s agricultural industry has limited resources available to address all security related matters and it is very important that those resources are spent wisely to coincide with the appropriate level of risk for each particular facility…”

Editor’s note, April 18: An explosion Wednesday at a fertilizer plant north of Waco, Texas, killed between five and 15 people, authorities say, and injured more than 160. The U.S. Chemical Safety Board, an independent agency that investigates chemical accidents and issues safety recommendations, says it expects a “large investigative team” to arrive at the scene this afternoon. As the Center for Public Integrity reported Wednesday, the board has been criticized for failing to complete investigations in a timely manner.

On April 2, 2010, an explosion at the Tesoro Corp. oil refinery in Anacortes, Wash., killed five workers instantly and severely burned two others, who succumbed to their wounds.

Eighteen days later, the Deepwater Horizon drilling rig blew up in the Gulf of Mexico, killing 11 workers and unleashing a massive oil spill.

In both cases, the U.S. Chemical Safety Board — an independent agency modeled after the National Transportation Safety Board — launched investigations. Like the NTSB, the Chemical Safety Board is supposed to follow such probes with recommendations aimed at preventing similar tragedies.

Yet three years after Tesoro and Deepwater Horizon, both inquiries remain open — exemplars of a chemical board under attack for what critics call its sluggish investigative pace and short attention span. A former board member calls the agency “grossly mismanaged.”

The number of board accident reports, case studies and safety bulletins has fallen precipitously since 2006, an analysis by the Center for Public Integrity found. Thirteen board investigations — one more than five years old — are incomplete.

As members of Congress raise questions, the Environmental Protection Agency’s inspector general is auditing the board’s investigative process.