Jurors have ruled in favour of poultry companies that were sued over litter produced by chickens that were fed Roxarsone, an arsenic-containing feed additive, reports Northwest Arkansas Times.

They found for the defendants – poultry companies George's Farms, Tyson Foods and Simmons Foods – in the suit in which Michael 'Blu' Green and his parents alleged that exposure to the litter caused his leukemia in the 1990s.

It was 9-3 in favour of the defendants in the civil trial.

"This was a case that had Blu's name attached to it but it wasn't just about him," his mother, Beth Green, said last week.

"This was a case about 17 children in a seven-year period in Prairie Grove that were diagnosed with cancer," she said. "Our fear because of this verdict is that it opens the door for companies like Tyson to use this product again, or other companies to continue using the product."

She also said "We've been under a gag order for many years so the story could not be told in full".

Gary Mickelson, spokesman for Tyson, said, "We're grateful for the jury's decision, which confirms poultry litter was not the cause of Mr. Green's unfortunate illness. We appreciate the jurors' time and attention during the trial and feel vindicated by their verdict."

The Greens made the same claim about chicken litter in 2006 against the companies, which were eliminated as defendants prior to trial by 4th Circuit Judge Kim Smith, leaving Alpharma Inc., the maker of Roxarsone, the lone defendant.

After three weeks of hearing testimony and evidence, a Washington County jury in 2006 found for Alpharma. It took them 21 minutes to reach the verdict.

The Arkansas Supreme Court later ruled that the poultry companies should have been tried, too, which is why this latest trial was conducted.

This time, it took jurors about two hours to reach a verdict.

The plaintiffs claimed, as they did in 2006, that the chicken litter turns into a dangerous form of arsenic that made Mr Green and other children ill as it was spread on Prairie Grove area fields in the 1990s.

The last trial took three weeks, and this one was considerably shorter, lasting only about two weeks. The defence rested on 13 May, and the jury was excused for the day. Both sides gave closing arguments on 14 May, and jurors began deliberating at 14:25. They had reached a verdict within two hours.

Jason Hatfield, an attorney for the plaintiffs, in his closing argument that if jurors found for the plaintiffs on the defective product or negligence claim, the Greens would win the case.

He said there were four elements to consider for the defective product claim that included the poultry companies made feed with Roxarsone, which contained arsenic, and that Mr Green sustained damage from exposure to the arsenic.

Attorney Hatfield talked about dust from the litter spread in the area "over and over and over again" and its effects on children in Prairie Grove area homes and schools. "We know these kids were breathing it," he said.

Woody Bassett, attorney for George's, said that it was not fair that Mr Green got leukaemia, but "that doesn't mean anyone is to blame for it".

"There's not a person in this courtroom who doesn't wish [Blu Green] the best in all the years to come."

He gave credit to the Greens for persevering through the illness with their son.

But, he said, "This lawsuit never should have been filed," he said, "because we have not done anything wrong."

Mr Bassett said the plaintiffs' experts were willing to say anything for pay "to create a case out of nothing". He said they did not bring the jury any reliable science to consider. He contrasted that with "first-class scientists" and other experts the defence brought out that provided "honest, reliable and objective" opinions based on reliable science.

The key point he brought out from expert testimony for the defence, he said, is that the form of leukaemia Mr Green had is not caused by exposure to arsenic.

"That is the evidence you can rely on," he said.

He said the product in the chicken feed at issue has been repeatedly tested and is approved by the US Food and Drug Administration.

Mr Hatfield said the inorganic arsenic created from the litter is a Class I carcinogen.

On the negligence claim, Mr Hatfield said jurors had to prove that the companies failed to warn and instruct the people in the Prairie Grove area about the use of the feed additive in the chicken feed, and this was a "proximate cause" of Mr Green's damages.

Mr Bassett said, "There's no danger to warn about."

Mr Hatfield said as the spreading of litter has dwindled throughout the years, the cases of cancer in children have ebbed.

He said there were two reported cases of leukaemia in adults from the Arkansas Department of Health and four cases of leukaemia in children over a five-year period in a town of about 2,500 people.

"That's evidence that supports our claim," he told Northwest Arkansas Times.