YAKIMA, Wash. (AP) - A federal institute has agreed to review workers' compensation benefits available to former weapons workers at the Hanford nuclear reservation.

U.S. Sen. Maria Cantwell, D-Wash., requested the review last month, citing a recent audit at the south-central Washington site that found insufficient data about workers' radiation exposure between 1944 and 1968.

The lack of data could lead federal officials to underestimate workers' exposure, thereby making them ineligible for workers' compensation benefits, Cantwell said.

In a letter to Cantwell dated Nov. 4, the National Institute of Occupational Safety and Health said its advisory board is expected to discuss the audit's findings and evaluate benefits available to former Hanford workers at its January meeting.

"This is the right decision," Cantwell said in a statement Thursday. "Right now, we don't know the full extent of workers' exposure to toxins. We need to review the situation to make sure all former Hanford employees get the help they need."

The occupational-safety institute has been struggling for months to gather data on the amount of radiation that Cold War-era workers in nuclear weapons plants may have been exposed to at Energy Department sites nationwide.

Under a 2000 law, the agency must determine possible radiation-exposure levels for each worker's compensation claim. Thousands of claims have been filed nationally, but worker records are missing at some sites and incomplete at others.

In 2004, the institute credited the Hanford site for providing information needed to begin estimating worker exposure.

However, the audit released June 10 noted several problems in data collection at the site, including use of inappropriate, incomplete or insufficient data that undercut claims.

Cantwell said the findings raise the possibility that former workers could be automatically eligible for workers' compensation, as has been the case at nuclear sites in Ohio, Kentucky, Tennessee and Alaska.

In many of those cases, workers contracted certain kinds of cancer, worked at specific sites, weren't carefully monitored or their records were lost.

According to the NIOSH Web site, a previous petition for automatic eligibility at Hanford was denied.

To date, the U.S. Department of Labor has received 2,171 applications from former Hanford workers who contend they experienced radiation exposure and are seeking workers' compensation benefits, according to Cantwell's office.

The 586-square-mile Hanford site was created in the 1940s as part of the top-secret Manhattan Project to build the atomic bomb. Today, it is the nation's most contaminated nuclear site, with cleanup costs expected to total $50 billion to $60 billion.