In the 1950s, Jane Wagner worked in the lab at the former Vitro Manufacturing Co. in Canonsburg.

Each day, wearing only a lab coat over her clothes, she would analyze samples brought in from the plant for various metals -- including uranium. At least some of the material was radioactive, but she was unaware of that.

"We knew we were dealing with uranium, but nobody ever mentioned radiation. The bosses probably knew, but we didn't know," she said last week.

Seven years ago, the Washington, Pa. woman found out she had breast cancer and underwent a mastectomy. Even though she is cancer-free today, that experience may qualify her for at least $150,000 in compensation payments from the federal government.

The U.S. Department of Labor ruled recently that former Vitro employees would be treated as a "special exposure" group under the eight-year-old law that compensates employees at former nuclear weapons plants.

The designation entitles the Vitro workers or their surviving family members to the $150,000 lump sum payment and coverage of certain medical costs if they were employed at the plant for more than 250 days between 1942 and 1957 and if they later were diagnosed with one of 22 specified cancers.

The government has been adding these exposure groups rapidly in recent years. But many of the workers they are designed to compensate have died, and only family members are left to get benefits.

The law, known as the Energy Employees Occupational Illness Compensation Program, was drafted during the Clinton administration.

David Michaels, a George Washington University epidemiology professor who helped write the law, said it was designed to redress decades of inadequate protection for nuclear weapons workers.

It also was intended to reverse past policies of the Department of Energy, he said, which for decades had denied responsibility for health problems, made it difficult for workers to obtain their medical records and blocked requests for compensation.

The Vitro plant, which operated on 17 acres on Strabane Avenue in Canonsburg, was part of a vast complex of sites around the nation where employees worked on the Manhattan Project atomic bomb program and then helped produce nuclear weapons after World War II.

Many people are familiar with names such as Los Alamos, N.M., and Oak Ridge, Tenn., but don't know about scores of other processing plants, laboratories and steel mills where workers participated in the weapons program.

The Vitro site had a long history in Canonsburg. Before Vitro began operations there in the 1930s, the plant had been known as Standard Chemical Co., and produced the highly radioactive element radium, some of which was given to Nobel Prize winner Marie Curie, who visited the plant in the 1920s.

In the 1980s, more than 20 years after the plant ceased operations, the federal government spent more than $40 million -- $107 million in today's money -- to bury radioactive waste under a clay mound at the site and decontaminate houses nearby. The grassy area is still surrounded by a chain-link fence posted with yellow radiation warning signs.

In interviews, former workers and their relatives said Vitro employees were proud to be part of the secretive national defense program, but said they were told little about the dangers they faced.

Jennie Senkinc's husband, Max, worked at the plant for seven years before and after World War II and died of bladder cancer in 1995.

"I didn't think there was anything wrong, because he was being monitored," said Mrs. Senkinc, of Canonsburg.

But when government employees showed up 40 years later to inspect the site and they were "dressed head to toe in coveralls, that's when I thought, 'uh-oh.' "

In a 1982 interview in the Washington Observer-Reporter newspaper, Max Senkinc recalled standing in railroad cars with nothing but work clothes and work gloves on, shoveling "yellowcake" uranium ore.

"We thought it was better than gold," he recalled. "Jobs had been hard to come by for so long, and then came the war years. The place was so busy we worked six-day weeks sometimes. Oh, my aching back -- I half thanked God when I was drafted.

"They brought the ore to us in cobblestones and we'd pulverize it to powder," Mr. Senkinc said. "We all breathed the stuff, wore it, ate it."

Another former worker, Ambrose Amolini, said in the same article that when his wife laundered his dust-caked work clothes, they would clog the washing machine. She also noticed small burn holes in his clothes.

"If it eats your clothes, can't it eat you?" he wondered years later.

Sam Amorose of Canonsburg, whose brother, Anthony, worked at the plant before World War II, has similar memories.

"Whenever he used to come home," Mr. Amorose said last week, "his wife would say, 'What are these, cigarette burns on your clothes?' and my brother didn't smoke, and here it was that stuff he was working with."

Under the federal compensation law, the first job of the National Institute for Occupational Safety and Health is to determine if it can calculate the dosage of radiation a nuclear plant worker was exposed to, using remaining records of air monitoring, radiation badges worn by employees, urinalysis and other reports.

Dr. Michaels, the George Washington University professor, said the dosage calculations are based primarily on experience from the atomic bomb explosions on Hiroshima and Nagasaki.

If it lacks adequate records to do the calculations, but has evidence workers were exposed to damaging radiation, the institute can create a "special exposure" group that presumes anyone who later got certain kinds of cancer was harmed on the job.

Larry Elliott, director of the institute's Office of Compensation Analysis and Support in Cincinnati, said the agency has added 39 groups covering about 2,270 workers or their families since 2005.

In all, the federal government has now distributed more than $4.5 billion to about 48,000 people under the compensation program.

Dr. Michaels acknowledged there are two ways to look at that.

One is that the compensation is too little, too late for many families. The other is that the program, starting from scratch in 2001, has been one of the more generous and successful compensation programs ever launched by the federal government.

Both are true, he said.

For many years, the Department of Energy -- formerly known as the Atomic Energy Commission -- stuck to a "deny and defend" policy when confronting nuclear weapons workers who said their jobs had made them sick, he said.

In President Bill Clinton's second term, though, as unions and disaffected workers demanded action, the administration changed the government's stance, Dr. Michaels said.

In a book he wrote last year, "Doubt Is Their Product: How Industry's Assault on Science Threatens Your Health," he recalled how he was assigned to meet with nuclear workers in Oak Ridge.

After hearing them out, he said, "crystal clear were two facts: These civilian workers had put themselves in harm's way while producing the nuclear weapons on which this nation had relied for its defense for half a century, and they had not been informed of the dangers, for the most part, much less provided with adequate protection."

The same could be said of the former Vitro workers, Dr. Michaels said last week.

The occupational safety institute got its first batch of claims in July 2001, Mr. Elliott said, and since then has processed more than 23,000 dosage calculation requests from around the country. It still has 5,000 claims pending, about 1,000 of which are more than two years old.

"We here at NIOSH are doing the best we can to process the claims as quickly as we can," he said.

It's a process that has come years too late for many former weapons workers. But even some of their relatives understand why it took so long to recognize the dangers.

Richard Chesnik, the son of former Vitro worker Albert Chesnik, remembers visiting his dad at the plant as a child and walking around the grounds. He wasn't the only child permitted to do so.

"Obviously if they had thought it was dangerous no one would have invited their children there."

And radiation wasn't the only danger that was underestimated in those days, Mr. Chesnik said.

"I remember having a jar of mercury at home and playing with it on the floor. Or using asbestos to insulate our house. Things you didn't know in those days you know now. We tend to look at the past through today's lenses."