Two retired sisters have filed a petition that might make it easier for Hanford workers to be approved for compensation for cancers potentially caused by exposure to radiation.

The petition has been qualified by the National Institute for Occupational Safety and Health, or NIOSH, which means the agency agrees that all required information has been provided. NIOSH now has 180 days to evaluate the petition.

The petition covers all Hanford employees from 1942 through 1990 - which includes the nuclear reservation's plutonium production years - who developed any of 22 cancers.

They or their survivors would be eligible for $150,000 in compensation from the federal government and coverage of medical expenses.

Sen. Maria Cantwell, D-Wash., urged the agency Thursday to give the petition a thorough and fair review.

"Too many of these workers have waited years for help," Cantwell said in a statement. "We need to get them the help they deserve without any further delays."

Now, Hanford workers and their survivors receive compensation for radiation-related cancers only if the federal government determines there is at least a 50 percent chance that radiation exposure at work caused the cancer.

However, certain workers at other sites, such as the Nevada Test Site, don't have to meet the 50 percent threshold. The federal government has determined that it's not feasible to determine whether radiation likely caused their illness, often because monitoring was inadequate or radiation records are not available.

Rosemary Hoyt, of Lyle, and her sister, Mary Ann Carrico, believe their father's death at the age of 47 likely was caused by working at Hanford.

He did construction and maintenance work at the nuclear reservation from 1942 until 1961, when he could no longer pass the physical because of colon cancer, Hoyt said.

She and her sister applied for compensation, but have twice been denied.When their father's estimated dose of radiation was compiled using availablehistorical records, the government decided the chance of the cancer being caused by Hanford radiation exposure was just41 percent.

The family does not have a history of cancer, Hoyt said.

Before the sisters filed their petition for Special Exposure Cohort status, Carrico traveled to Richland and contacted people they had known growing up in Richland and others they'd heard about through word of mouth.

"My sister interviewed people and came up with heartbreaking stories," Hoyt said.

The children of one deceased worker shared a memoir he'd written that described workers being coerced into falsifying records, Hoyt said. Workers kept their own monitoring records and if they met the radiation limit, they were sent home without pay, according to the memoir.

But the petition finally qualified for review not on descriptions from individual workers, but on grounds raised in an 2005 audit prepared by S. Cohen and Associates. It looked at a case history compiled for Hanford to help the government determine which individual cases of cancer might be linked to work at Hanford.

Cantwell is urging NIOSH to consider whether the findings of the audit suggest that insufficient data on worker radiation exposure between 1944 and 1968 may lead to ill workers unfairly being denied compensation.

The audit found potentially significant exposures of reactor workers to unmeasured neutrons and unplanned airborne releases of radionuclides, according to Cantwell's staff. The report noted inconsistencies over time in recording worker radiation exposure and insufficient measurements taken for internal exposure to recycled uranium, her staff said.

To date, 496 Hanford workers or their survivors have received the $150,000 payment because they developed cancer or berylliosis, a rare lung disease.