SPOKANE — A federal judge has been asked to apply new rules for compensating sick nuclear workers to people who claim they were harmed by releases from the Hanford nuclear reservation.

Lawyers for the so-called "Hanford Downwinders" asked U.S. District Judge William F. Nielsen to determine which standard of proof to use at a trial scheduled to start April 11.

Nielsen did not say Wednesday when he would rule on the standard in the lawsuit filed in 1991 by thousands of people who claim they developed thyroid cancer and other diseases after being exposed to radiation from Hanford's plutonium factories.

The Energy Department formerly barred sick workers from qualifying for a $150,000 compensation payment unless they could prove that they wouldn't have gotten cancer except for their on-the-job exposure.

The Labor Department, which is taking over the workers' compensation program, will use a less stringent compensation standard: that radiation the workers were exposed to was a "significant factor" in increasing their cancer risk.

Downwinders lawyers argued Wednesday that Nielsen should use the new standard of proof at trial.

Lawyers representing the contractors argued that a strict burden of proof should still be used to determine who is eligible to sue in the case.

"Downwinders are entitled to the same standard. How can you have one standard for workers and a stricter one for the general public?" lead plaintiff attorney Dick Eymann asked.

"This whole field has evolved," attorney Tom Foulds of Seattle told Nielsen. "Any radiation will create some risk to human cells."

The burden of proof should focus on epidemiological studies and statistics to determine which plaintiffs "more likely than not" were harmed by Hanford emissions, said Kevin Van Wart of Kirkland & Ellis of Chicago, lead attorney for the Hanford contractors.