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).

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.

Congress, the Occupational Safety and Health Administration and the Justice Department are beginning to respond to the NPR-Center for Public Integrity Series on hundreds of persistent and preventable deaths in grain storage bins and weak enforcement by federal agencies.

Two federal officials familiar with the case say that the Justice Department is again considering criminal charges in the incident in Mt. Carroll, Ill.,in 2010, in which 14-year-old Wyatt Whitebread and 19-year-old Alex Pacas suffocated in thousands of bushels of corn. Will Piper, 20, survived but was unable to save his friends and co-workers. The owner of the grain bin, Haasbach LLC, was initially fined $555,000 but OSHA cut the fine by more than 60 percent.

NPR/CPI obtained Labor Department documents that showed the Justice Department initially declined to file criminal charges in the case, despite multiple willful violations and what one former OSHA official called "the worst of the worst" cases.

The officials now tell NPR that the Justice Department asked the Labor Department to again provide the Mt. Carroll case files. The request was made in January when NPR and CPI were pressing the agency to respond to questions about the case.

"They're taking another look" at the Mt. Carroll incident, one source said.

"They should reconsider," says Annette Pacas, Alex's mother. "It was a crime. They killed two kids. It should be prosecuted as a crime."

Wyatt Whitebread's mother Carla is hoping criminal charges will follow.

Targeting a law critics chide as dated and weak, Sen. Patty Murray has introduced legislation that would strengthen the 1970 law governing workplace safety.

The bill, called the Protecting America’s Workers Act, addresses regulatory gaps that The Center for Public Integrity has highlighted as part of the ongoing series Hard Labor.

“This legislation is a long-overdue update to the [Occupational Safety and Health] Act, and a good step towards making workplaces safer and healthier across America,” Murray, a Democrat from Washington state, said in a statement. Ten other Democratic senators have signed on as co-sponsors.

Similar legislation has died in previous years amid opposition from industry groups. The Chamber of Commerce and the National Association of Manufacturers did not respond to interview requests Thursday.

The bill would give the Occupational Safety and Health Administration more powerful enforcement tools.

Currently, an employer whose willful violation of the law leads to a worker’s death faces a misdemeanor and a maximum six-month prison sentence. A person could face twice the prison time for harassing a wild burro on public lands. Murray’s bill would make knowing violations that lead to a worker death a felony, punishable by up to 10 years in prison.

The legislation also would increase civil penalties, which have not been changed since 1990. OSHA is one of few federal agencies excluded from a law that allows fines to rise over time with inflation.

MT. CARROLL, Ill. — Will Piper and Alex Pacas were being buried alive.

It was July 28, 2010, just before 10 a.m., and the young men strained to breathe as wet corn piled up around them in Bin No. 9 at the Haasbach LLC grain storage facility. A co-worker, Wyatt Whitebread, had already been pulled under.

The ordeal in Bin No. 9 played out over 13 hours as hundreds of townspeople maintained a vigil outside. In the end, Whitebread, 14, and Pacas, 19, were dead. Piper, 20, avoided suffocation by inches.

Whitebread, compact and athletic, was happy to have summer work. Pacas, slight and musical, was an aspiring electrical engineer just days away from returning to classes at Hamilton Technical College in Davenport, Iowa. He’d started at Haasbach the day before.

“He prayed for his life,” survivor Piper said of Pacas’s last moments. “He said all he wanted to do is see his brothers graduate high school. And then he spouted off the Lord’s Prayer very quickly, and shortly after that one last chunk of corn came flowing down and went around his face.”

The three had been hired to keep corn flowing in the bin, one of 13 in the Haasbach complex on Mill Road in Mt. Carroll, population 1,700. They’d been sent in with pick axes and shovels that morning to break up corn piled 10 to 24 feet high in the bin and knock clumps from the walls. No one had told them they needed to wear safety harnesses — stored in a red shed nearby — to keep from sinking.

“I had no idea that someone could get trapped and die in the corn,” Piper told investigators with the Department of Labor’s Occupational Safety and Health Administration.

Grain storage in the United States is surging, in part because of the boom in biofuels. Yet at worksites, farmers and commercial operators keep making the same mistakes. Workers, some of them young, keep drowning in grain or getting hurt.

Should farms be regulated?

Corn storage on farms and in commercial structures doubled between 1978 and 2010, climbing from 5.4 billion bushels to a record 10.93 billion bushels, according to the U.S. Department of Agriculture.

With growth has come tragedy: worker entrapment deaths in corn or other grains — wheat, barley, soybeans — hit a recent peak in 2010, a Center for Public Integrity-NPR investigation found. In at least 51 incidents that year, 26 bodies were recovered. More than two-thirds of the entrapments occurred on farms, as did four of six incidents involving workers under 16.

Commercial operations are overseen by the U.S. Occupational Safety and Health Administration. Most farms aren’t — but perhaps should be, some say.

“We’ve got farmers who are building more space and bigger space, and it’s going to cause more issues,” Jeff Adkisson, executive vice president of the Grain and Feed Association of Illinois, which represents commercial operators, said at a grain bin safety conference in Cedar Rapids, Iowa, last fall. “I think it’s time for industry, for government, for all of us to pause and have the conversation again about who is exempt and who is not exempt from some of the standards.”

Adkisson and others in the grain-storage industry have said for years that the bulk of entrapments occur on farms. This is based largely on the work of Purdue University professor William Field, who has put 70 percent of the incidents with reported locations on farms, 30 percent at commercial facilities.

But the Center and NPR found 60 fatal and five non-fatal cases in an OSHA enforcement database that were not included in Field’s studies. All occurred at commercial operations.

In response, Field redid his numbers. He found that 52 percent of the entrapments with known locations took place on farms, 48 percent at commercial facilities.

A group of House Democrats introduced legislation this week that aims to protect workers from combustible dust – a fire and explosion threat that has killed or injured hundreds in recent decades.

Last year, the Center for Public Integrity examined the toll triggered by recent preventable tragedies – and the political and bureaucratic forces that impeded greater protection from a hazard recognized for more than a century. Workers across a range of industries face dust dangers from materials as varied as sugar, coal, wood and plastic.

The federal Occupational Safety and Health Administration began the process of issuing a rule to address the hazard in 2009, but its progress has stalled.

The new bill, announced Thursday, would compel the agency to issue interim protections within a year and set deadlines for finalizing a permanent rule.

“While OSHA has taken some limited steps to protect workers and property from combustible dust explosions, the widely recommended protections necessary to prevent these explosions are caught up in red tape and special interest objections,” Rep. George Miller, the senior Democrat on the House Committee on Education and the Workforce, said in a statement announcing the bill’s introduction.

A new federal advisory panel report makes a forceful case for more research into environmental causes of breast cancer, which was diagnosed in 227,000 women, killed 40,000 and cost more than $17 billion to treat in the United States last year.

Compiled by the congressionally mandated Interagency Breast Cancer and Environmental Research Coordinating Committee, the report notes that most cases of breast cancer “occur in people with no family history,” suggesting that “environmental factors — broadly defined — must play a major role in the etiology of the disease.”

Yet only a fraction of federal research funding has gone toward examining links between breast cancer and ubiquitous chemicals such as the plastic hardening agent bisphenol A; the herbicide atrazine; and dioxin, a byproduct of plastics manufacturing and burning, says the report, prepared for Health and Human Services Secretary Kathleen Sebelius and released today.

“Prevention needs to be as important as other investments that are made in screening, treatment and access to care,” Jeanne Rizzo, co-chair of the committee and president of the San Francisco-based Breast Cancer Fund, said in an interview. “There really is a problem, and until we address it we’re going to continue to have a quarter of a million new cases every year.”

Workplace safety and health regulators should conduct an enforcement blitz and amend policies to give greater protection to the growing number of vulnerable temporary, or “contingent,” workers, a new report recommends.

The report from the Center for Progressive Reform, a nonprofit research and advocacy group, echoes many of the findings of a December Center for Public Integrity story detailing the increasing use of contingent workers to perform some of the most hazardous, undesirable jobs.

The number of contingent workers has more than doubled during the past two decades, with the current total estimated at more than 2.5 million, according to the U.S. Bureau of Labor Statistics. Recent studies have indicated that contingent workers suffer injuries at higher rates than other employees.

Use of such workers is particularly popular in industries such as farming, construction, warehousing and hotel services, the group’s report says. Unable to outsource these jobs, companies have turned to contingent workers to reduce labor costs, the report says. By using contingent workers, the employer can avoid paying for workers’ health insurance and workers’ compensation costs, eliminating incentives to provide safe workplaces, the CPR researchers say.

Steven Berchem, the chief operating officer of the American Staffing Association, said in a statement, "We have not had an opportunity to review the report, but worker safety is paramount to our members and the American Staffing Association is actively engaged in continual efforts to ensure safe working conditions for temporary and contract employees."

Yet these workers are often assigned to dangerous work and not given the proper training or safety equipment, the new report says.