ALBUQUERQUE, N.M. (AP) — About a quarter of Navajo women and some infants who were part of a federally funded study on uranium exposure had high levels of the radioactive metal in their systems, decades after mining for Cold War weaponry ended on their reservation, a U.S. health official Monday.

The early findings from the University of New Mexico study were shared during a congressional field hearing in Albuquerque. Dr. Loretta Christensen — the chief medical officer on the Navajo Nation for Indian Health Service, a partner in the research — said 781 women were screened during an initial phase of the study that ended last year.

Among them, 26% had concentrations of uranium that exceeded levels found in the highest 5% of the U.S. population, and newborns with equally high concentrations continued to be exposed to uranium during their first year, she said.

The research is continuing as authorities work to clear uranium mining sites across the Navajo Nation.

"It forces us to own up to the known detriments associated with a nuclear-forward society," said U.S. Rep. Deb Haaland, who is an enrolled member of Laguna Pueblo, a tribe whose jurisdiction lies west of Albuquerque.

The hearing held in Albuquerque by U.S. Sen. Tom Udall, Haaland and U.S. Rep. Ben Ray Lujan, all Democrats from New Mexico, sought to underscore the atomic age's impact on Native American communities.

The three are pushing for legislation that would expand radiation compensation to residents in their state, including post-1971 uranium workers and residents who lived downwind from the Trinity Test site in southern New Mexico.

The state's history has long been intertwined with the development of the nation's nuclear arsenal, from uranium mining and the first atomic blast to the Manhattan project conducted through work in the once-secret city of Los Alamos. The federal Radiation Exposure Compensation Act, however, only covers parts of Nevada, Arizona and Utah that are downwind from a different nuclear test site.

During the hearing, Haaland said one of her own family members had lost his hearing because of radiation exposure. At Laguna Pueblo, home to her tribe, the Jackpile-Paguate Mine was once among the world's largest open-pit uranium mines. It closed several decades ago, but cleanup has yet to be completed.

"They need funds," Haaland said. "They job was not completed."

David Gray, a deputy regional administrator for the U.S. Environmental Protection Agency, said the mine illustrates uranium mining and milling's lingering effects on Indian Country.

On the Navajo Nation, he said, the EPA has identified more than 200 abandoned uranium mines where it wants to complete investigation and clean up under an upcoming five-year plan, using settlements and other agreements to pay for the work that has taken decades.

Udall, who chaired the hearing, acknowledged federal officials had shown progress but that the pace of cleanup has proven frustrating for some community members.

"They feel an urgency," Udall said. "They feel that things need to happen today."

In her testimony, Christensen described how Navajo residents in the past had used milling waste in home construction, resulting in contaminated walls and floors.

From the end of World War II to the mid-1980s, millions of tons of uranium ore were extracted from the Navajo Nation, leaving gray streaks across the desert landscape, as well as a legacy of disease and death.

While no large-scale studies have connected cancer to radiation exposure from uranium waste, many have been blamed it for cancer and other illnesses.

By the late 1970s, when the mines began closing around the reservation, miners were dying of lung cancer, emphysema or other radiation-related ailments.

"The government is so unjust with us," said Leslie Begay, a former uranium miner who lives in Window Rock, an Arizona town that sits near the New Mexico border and serves as the Navajo Nation capital. "The government doesn't recognize that we built their freedom."

Begay, who said he has lung problems, attended the hearing with an oxygen tank in tow. The hearing held in the Southwest was especially meaningful for him after traveling in the past to Washington to advocate for himself and others, he said.