PROVIDENCE -- Lawyers for former lead paint manufacturers spent yesterday trying to get a state's witness to contradict his earlier testimony on the origins, effects and permanency of lead paint poisoning.

Donald E. Scott, lawyer for NL Industries, struck at the heart of the case, in which the state accuses paint companies of creating a public nuisance by making and selling lead-based paints that poison children in Rhode Island.

He asked the witness, Dr. Philip J. Landrigan, professor and chairman of the Department of Community and Preventative Medicine at Mount Sinai School of Medicine in New York, about a study that measured levels of lead in people in areas of the world where there was no exposure to lead paint.

In this study, "the researchers went off by foot," Scott told the jury, "and by trail into a very remote area into the Himalayas in Tibet. . . to find out what the blood lead levels were for adults and children who were not exposed to paint" or other industrial lead sources.

"Do you recall the average blood lead level they found?" Scott asked.

Landrigan said it was "close to" 2 micrograms per deciliter, about the same as average lead levels found in Rhode Island.

Scott also probed Landrigan on a government study of the relationship between lead exposure and IQ; several times he asked the doctor to acknowledge that the study concluded that a child's blood lead level was only a statistically significant indication of cognitive ability at 2 years old and that at ages between 12 months and 10 years, there was no causal relationship.

However, Landrigan said that as lead levels rose, test scores dropped.

"The trend was still in the wrong direction," but just because the sample was too small to be significant "does not mean that there is no correlation, sir," he said.

Michael Nilan, lawyer for Millennium Holdings, another defendant in the trial, questioned Landrigan's testimony about the origins of environmental lead.

Gasoline's contribution to lead poisoning is "absolutely minimal," Landrigan testified Thursday. "It's been 15 years since any major amounts of lead have been used in gasoline in this country. It's washed off the surface. The lead has gone down into the sewers and rivers and gone, I suppose out to sea."

Nilan presented an article coauthored by Landrigan that referred to lead in gasoline as "a catastrophe for public health," and another article where he described lead in soil as "very persistent and relatively immobile. . .under normal conditions of acidity."

In response to the apparent contradictions, Landrigan said the first article was not restricted to the United States, and that it referred to a study done in the 1980s; lead was banned from use in gasoline in 1978.

And Rhode Island, he said, receives acid rain, not normal conditions of acidity.

Jack McConnell, lawyer for the attorney general's office, reexamined Landrigan, allowing him to restate much of what he said on Thursdayin Superior Court before Judge Michael A. Silverstein.

"Is there any doubt in your mind at all that lead exposure lowers a child's IQ?" McConnell asked.

"No doubt in my mind whatsoever," Landrigan replied.

"Is there a consensus in the medical community that exposure to lead lowers an IQ?"

"Yes."

"What is it?"

"Exposure of a child to even low levels of lead lowers a child's IQ."

Landrigan, a Harvard Medical School graduate, is a pediatrician and epidemiologist. His research focuses on preventative and environmental medicine.

Brandie Jefferson has a fellowship with the Metcalf Institute for Marine and Environmental Reporting. She can be reached at bjeffers [at] projo.com.