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.

Oil companies should phase out the use of a highly toxic acid that places millions at risk, a new report from the union representing many refinery workers says.

The report from the United Steelworkers cites data gathered and analyzed by the Center for Public Integrity for a 2011 story that found more than 16 million Americans live in the potential pathway of hydrofluoric acid (HF) if it were released in an accident or a terrorist attack.

The union’s report, drawing on the results of a survey of its local officials at 23 refineries that use the acid, says both regulators and oil companies have failed to ensure that it is handled safely and recommends steps that could protect workers and the public as refineries transition away from HF.

Officials at 18 of the 23 refineries reported a total of 131 accidents or near-misses involving HF during the previous three years.

“There must be a fundamental change in the oil industry’s use of HF,” the report concludes. “[Use of the acid] as it is currently performed in U.S. refineries is a risk too great, but that risk can be reduced and ultimately eliminated.”

The American Fuel and Petrochemical Manufacturers, a trade group, said Monday it had not yet seen the report. However, it said that "refiners have used HF safely for more than 70 years," and "switching from HF may either not be feasible or could simply serve to just shift risk to other parts of the supply chain."

Oil refiners use HF to boost the octane rating of gasoline.  The acid is an efficient catalyst, but it also has the potential to form a cloud that can travel long distances, sickening or killing those in its path.

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.