As federal regulators review a controversial program exempting government designated “model workplaces” from regular safety checks, newly released U.S. Occupational Safety and Health Administration records detail significant safety risks, injuries and even deaths at the sites across Massachusetts.

OSHA, the federal overseer of workplace safety, has also allowed some Massachusetts employers to retain their “Voluntary Protection Program” (VPP) status even after serious safety problems have been exposed or workers have been killed, according to more than 1,000 documents obtained by the New England Center for Investigative Reporting under a federal Freedom of Information Act request.

The VPP designation frees employers from regular health and safety inspections, and they are largely left to police themselves, a flaw that has contributed to the death of at least two Massachusetts workers, some critics said.

“If you're a VPP program, that should never happen,” said James Lee, a trustee with the American Postal Workers Union Local 497 and a member of the OSHA investigating team that reviewed a horrific 2006 fatal accident at a U.S. Postal facility in Springfield, Mass.  

“This would never have occurred if (OSHA) came in more frequently,” Lee said.

OSHA rarely strips VPP sites of their special status, even after violations are found or fatal tragedies occur, like the death of postal worker Robert J. Scanlon in Springfield and the 2004 death of a 34-year-old mother of three who was accidentally sucked into an adhesive coating machine at a Spencer, Mass., manufacturing firm, the OSHA documents show.

The Department of Labor reported today that 4,690 U.S. workers suffered fatal injuries in 2010, a 3 percent increase from 2009.

The higher number in part reflects a string of high-profile disasters in 2010: An explosion at the Upper Big Branch coal mine in West Virginia that killed 29; BP’s Deepwater Horizon blowout in the Gulf of Mexico, which killed 11; and a blast at the Tesoro Corp.’s oil refinery in Washington State that killed seven.

Even discounting the 47 deaths from those three events, the toll rose in 2010. In 2009, 4,551 workers died, according to the Bureau of Labor Statistics.

The fatality rate rose slightly as well, from 3.5 fatal injuries per 100,000 full-time equivalent workers to 3.6.

The number of workers killed in fires or explosions jumped from 113 in 2009 to 191 in 2010. Work-related transportation deaths increased from 1,795 to 1,857, suicides from 263 to 270.

The number of construction-related deaths fell from 834 to 774 — a probable reflection of a weak housing market and a generally rotten economy in 2010.

“It’s disturbing that there hasn’t been any improvement in workplace fatalities in several years,” said Peg Seminario, director of health and safety for the AFL-CIO. “It seems like progress has stalled.”

Small doses can have big health effects.

That is a main finding of a report, three years in the making, published Wednesday by a team of 12 scientists who study hormone-altering chemicals.

Dozens of substances that can mimic or block estrogen, testosterone and other hormones are found in the environment, the food supply and consumer products, including plastics, pesticides and cosmetics. One of the biggest, longest-lasting controversies about these chemicals is whether the tiny doses that most people are exposed to are harmful.

In the new report, researchers led by Tufts University’s Laura Vandenberg concluded after examining hundreds of studies that health effects “are remarkably common” when people or animals are exposed to low doses of endocrine-disrupting compounds. As examples, they provide evidence for several controversial chemicals, including bisphenol A, found in polycarbonate plastic, canned foods and paper receipts, and the pesticide atrazine, used in large volumes mainly on corn.

The scientists concluded that scientific evidence “clearly indicates that low doses cannot be ignored.” They cited evidence of a wide range of health effects in people — from fetuses to aging adults — including links to infertility, cardiovascular disease, obesity, cancer and other disorders.

“Whether low doses of endocrine-disrupting compounds influence human disorders is no longer conjecture, as epidemiological studies show that environmental exposures are associated with human diseases and disabilities,” they wrote.

In addition, the scientists took on the issue of whether a decades-old strategy for testing most chemicals — exposing lab rodents to high doses then extrapolating down for real-life human exposures — is adequate to protect people.

In the space of a minute, federal prison worker Jason Unwin was twice attacked by a furious, muscle-bound inmate on Dec. 21, 2010.

Agitated after a disciplinary hearing, the inmate first punched one of Unwin’s colleagues in the face, knocking him unconscious. He then turned to Unwin, a correctional counselor at the United States Penitentiary in Florence, Colo. “I was hit square in the face,” said Unwin, 51.

With a bloodied Unwin in pursuit, the inmate walked off. Seconds later, with Unwin briefly distracted, the inmate “blindsided me. He hit me with a closed fist, very hard, on the left side of the head. I was knocked unconscious.”

Unwin, a Federal Bureau of Prisons employee for 16 years, hasn’t worked since. He doesn’t have a full range of motion in his right shoulder, he said, and has been diagnosed with post-traumatic stress disorder. He has short-term memory problems, sleeps irregularly and faces seizure risks.

The saving grace: He is covered by a 96-year-old compensation program for injured federal workers. Under the Federal Employees Compensation Act of 1916 (FECA), he receives 75 percent of his former salary, tax-free; his monthly income is within a few hundred dollars of his previous salary.

Legislation pending in the U.S. Senate, however, ultimately would cut Unwin’s benefits and could affect many other government workers — especially those with modest incomes — in the future.

The measure, championed by Sen. Susan Collins, R-Maine, is included in a postal reform bill that may come up for a vote this month. Collins said it would stamp out abuses while saving money.

Yet officials with federal employees’ unions say the legislation would unfairly punish victims of workplace violence and other traumatic injuries — and their families.

Again drawn by a leak of toxic hydrofluoric acid, federal investigators are back at a Texas oil refinery they examined three years ago.

Some nearby residents were told to shelter in place after the release, said Daniel Horowitz, managing director of the U.S. Chemical Safety Board, which has sent a team of investigators to the Citgo refinery in Corpus Christi. It’s not yet clear how much of the acid, known as HF, got out.

“Any incident involving the release of HF is something we take very seriously,” Horowitz said.

A Center for Public Integrity investigation last year found that 50 refineries use the acid despite the availability of safer alternatives. At least 16 million Americans live in the path of a toxic cloud in the event of an accident.

A close call at the Citgo refinery was one of three major accidents involving HF in 2009. The CSB investigated that accident and issued urgent recommendations to Citgo. The board doesn’t have authority to issue citations or impose penalties.

A Citgo spokesman said the company had followed all of the board’s recommendations and that the accident on Monday “is not related to the 2009 incident.”

At about 7:15 p.m. on Monday, a leaking flange released materials including HF from a pipe, triggering water cannons meant to control the release, the Citgo spokesman said. The company’s monitoring data indicated that no chemicals escaped the unit where the leak occurred, he said.

After the 2009 accident, Citgo reported that about 30 pounds of the acid had gotten past its control systems, but the CSB later determined the real amount was likely about 4,000 pounds.

When Deidre Ramos moved with her infant son to the Parker Street section of New Bedford, Mass., little did she know that her new neighborhood was toxic.

Today, a decade later, Ramos is worried about the health of her two sons growing up in a community contaminated by an old burn dump containing polychlorinated biphenyls (PCBs).

“What will be the long-term effects on my children?” asked Ramos.

Now new research conducted in New Bedford suggests that these industrial chemicals, which were first linked to learning problems in children more than two decades ago, may play a role in attention-deficit hyperactivity disorder (ADHD), too.

Boys who were exposed to higher levels of PCBs in the womb scored lower on focus and concentration tests, which indicates that they are more likely to have attention problems often related to ADHD, according to a newly published study of New Bedford area children.

All of the children studied were born to mothers who lived near the contaminated harbor and dumpsites in these low-income communities, where twice as many people live below the poverty line than the Massachusetts average. But experts say that their exposure levels were fairly low, comparable to people's levels throughout much of the United States, which means that a connection between PCBs and attention problems in boys could exist in other communities, too.

Banned in the United States more than 30 years ago, PCBs are long-lived industrial chemicals that accumulate in food chains. Nearly every U.S. resident still has detectable levels in his or her blood. PCBs have the ability to disrupt hormones, which can alter how the brain develops.

A much-anticipated government study of more than 12,000 miners — whose publication was delayed by litigation from a group of mining companies — has found that exposure to diesel engine exhaust significantly increases the risk of lung cancer.

For the most heavily exposed miners, the risk of dying from lung cancer was three times higher than it was for those exposed to low doses. For non-smokers, the risk was seven times higher.

“[T]he findings suggest that the risks may extend to other workers exposed to diesel exhaust in the United States and abroad, and to people living in urban areas where diesel exhaust levels are elevated,” Joseph Fraumeni Jr., director of the National Cancer Institute’s Division of Cancer Epidemiology and Genetics, said in a press release Friday morning.

Two papers detailing the study’s results were published in the Journal of the National Cancer Institute. One of them concluded that diesel-induced lung cancer “may represent a potential public health burden.”

In an editorial in the journal, Lesley Rushton, an epidemiologist at Imperial College in London, wrote, “These results indicate that stringent occupational and particu­larly environmental standards for [diesel exhaust] should be set and compli­ance ensured to have an impact on health outcomes.” The setting of stricter standards could have broad implications given the ubiquity of diesel engines in trucks, buses, ships, trains and construction equipment.

The Department of Labor’s Office of Inspector General will examine a federal program that recognizes “model workplaces” and exempts them from regular inspections, the office’s audit plan for the coming fiscal year shows.

The assessment comes as an Occupational Safety and Health Administration task force is conducting its own review of the agency’s Voluntary Protection Programs — the subject of a recent Center for Public Integrity investigation.

The Center found that, since 2000, more than 80 workers have died at sites OSHA deemed the nation’s safest. But even when investigators found serious safety violations related to the fatal accidents, OSHA rarely used its authority to remove sites from the program.