The federal government confirms some people in the St. Louis area may have a higher risk of getting cancer. A recent health report found some residents who grew up in areas contaminated by radioactive waste decades ago may have increased risk for bone and lung cancers, among other types of the disease. The assessment was conducted by the Agency for Toxic Substances and Disease Registry, a branch of the U.S. Centers for Disease Control and Prevention.

As CBS News correspondent Anna Werner reports, the situation is not unique to St. Louis because it's connected to America's development of its nuclear weapons program decades ago. Radioactive wastes persist in soils, and many believe that's why they or a loved one developed cancer. Now for the first time, federal health officials agree, on the record, that's a real possibility.

"You'll never forget the moment they tell you, 'We found lesions on your lung and your liver,'" Mary Oscko told CBS News three years ago.

Mary Oscko. CBS News

She had been diagnosed with stage 4 lung cancer in 2013, despite never touching a cigarette. She's now on the last drug her doctors can offer, to hold her cancer at bay.

"I'm not ready to die yet," she said. "I have things to contribute to society."

Oscko and her husband Gerard are just two of many who believe their families' cancers were caused by decades-old radioactive contamination. In the 1940's and 1950's, St. Louis was key to America's nuclear weapons program. The government hired the Mallinckrodt Chemical Company to process uranium used to make the atomic bombs dropped in Japan in World War II.

The radioactive wastes from that processing were then stored at sites in North County. Tens of thousands of barrels, many stacked and left open to the elements, contaminated the soil and nearby Coldwater Creek. It's the creek that sometimes flooded the park next to the Oscko's house.

The Army Corps of Engineers has cleaned up two major sites and has spent years testing hundreds of properties along Coldwater Creek.

"The testing and sampling itself is extremely complicated," said Bruce Munholand, the project manager.

He says trucking activities caused some of the contamination.

"They did not practice very good techniques as far as hauling, the trucks were uncovered and things were just allowed to proceed sloppily so all along the whole route debris would just fall off the trucks," Munholand said.

That means figuring out precise health risks was a challenge for federal scientists, like Jill Dyken.

"Trying to get a good estimate of what the contamination may have been in the past was one of the tougher questions that we had to deal with," she said.

Despite that, Dyken and her colleagues did find distinct potential risks. For children who grew up near Coldwater Creek, or lived in its flood plain for many years in the 1960s to the 1990s, the risk of some cancers may be higher, in particular for bone and lung cancers.

Federal scientists looked for potential cancer risks near Coldwater Creek. CBS News

The agency gave its results at community meetings in June. Still, many residents were left with unanswered questions. But activist Kim Visintine says the report marks progress.

"We would like to see additional areas testing and that study gave us that opportunity," Visintine said.

Her Facebook group began tracking suspicious cancers in 2012, and has pushed for health studies. But for Visintine, whose 6-year-old son died from a brain tumor 12 years ago, the report gives much-needed confirmation.

"For them to acknowledge that it is a possibility is a huge deal," Visintine said.

Three years ago, the Army Corps of Engineers found low-level radiation in the park next to the Oscko's home. It's cleaned up now, but they live with the knowledge that their children grew up playing there.

"We didn't know that or we wouldn't have bought this house," Oscko said.

"If I would've known, I could've done something and left," she said.

Some residents, including the Osckos, are suing Mallinckrodt and other companies that handled uranium and radioactive waste.

In a statement, Mallinckrodt said in part: "At all times, the company worked under the direction of the U.S. Government, as did other contractors, and at no time did Mallinckrodt own any uranium or its byproducts. The U.S. Government owned all the uranium raw materials, in-process product, byproducts and residues and determined site locations where work was performed. Further, for decades, the U.S. Department of Energy and the U.S. Army Corps of Engineers have been responsible for and are handling all clean-up efforts on these sites."