PORTLAND -- After eight days of testimony, U.S. District Court Judge Dennis Hubel still has questions in the federal trial in which 49 construction workers allege they were exposed to sarin five years ago at the Umatilla Chemical Depot.

The plaintiffs' experts, using Army air monitoring records to support claims, have argued sarin was detected in small doses in the incinerator building at the depot Sept. 15, 1999.

Four dozen construction workers simultaneously became ill that day while building the incinerator plant that will be used to destroy the 3,717 tons of the nerve agents sarin and VX and the blister agent mustard.

But the Army's experts say those detections were either below levels the monitors can accurately read, or that they were false positive readings caused by other industrial chemicals in the air.

Throughout the trial, medical and toxicology experts have agreed sarin's effects are dose dependent, meaning the severity of the symptoms is related to the amount of sarin workers may have been exposed to.

Hubel said he would like to find out what symptoms workers would have been expected to display if sarin actually was present in the building in the amounts plaintiffs' experts say was detected.

That could be a key in determining why none of the workers experienced miosis, or pinpoint pupils, a symptom prevalent among those exposed to sarin. Although many of the workers experienced eye pain and redness, none were diagnosed that day with miosis.

Hubel had hoped to draw some of those answers Thursday from environmental toxicologist Dr. Robert Golden, but James Brennan, a Department of Justice attorney representing the Army, objected.

Hubel, who has sporadically quizzed witnesses throughout the trial, said he knew the questioning might be a sensitive subject and had Golden leave the courtroom before asking attorneys if he could question the witness.

"I'm not sure if our witness is qualified to answer those questions," Brennan said.

Brennan said he also wasn't sure how Golden would answer the judge and, he added, it was up to the plaintiffs' attorney, James McCandlish, to prove his case with his own witnesses.

"That's fine, but these are questions I would like to have answered," Hubel said.

Attorneys were hoping to wrap up with closing arguments today, but that likely won't happen until Monday or Tuesday.