GADSDEN
Dr. Renate Kimbrough, a retired government scientist, testified Tuesday on behalf of Monsanto that PCBs do not cause significant health effects in humans. She told the Monsanto trial jury she believes PCBs are only "slightly toxic."
Kimbrough, a native German who moved to the United States in 1958, was first asked by Solutia, Monsanto's spin-off company, to review PCB health assessments in Anniston in 1995.
Twenty years prior to Solutia's request, Kimbrough concluded that PCBs cause liver cancer in rats. At the time, she was a laboratory scientist for the Centers for Disease Control in Atlanta.
However, in 1999, nine years after she retired from the federal government, Kimbrough concluded that PCBs do not cause cancer in humans. She published a decade-long General Electric-sponsored study of 7,000 of its employees in New York who were exposed to PCBs by skin contact or by breathing PCB-contaminated air. Although many of the GE workers were heavily exposed, the overall group did not have an elevated rate of cancer deaths, she testified.
PCBs are listed by the EPA as a probable carcinogen.
However, Kimbrough, a toxicologist, told the jury that PCBs do not cause cancer in people. Also, she said, the PCB exposures were more severe for GE plant workers than the plaintiffs in the PCB trial, who are suing Monsanto and Solutia for contaminating their blood and their properties with PCBs.
She explained that she first learned of possible human health effects from PCBs in the late 1960s after a poisoning outbreak in Japan.
Despite years of study, researchers have not successfully linked PCBs to clinical diseases, Kimbrough said. "There are problems with all of the studies."
Her research for government agencies began in 1972 after the Food & Drug Administration discovered that much of the U.S. fish supply was contaminated with PCBs. Kimbrough said she was part of a government team that was asked to find the "acute toxicity" of PCBs. Acute toxicity is the dosage of a chemical that will cause immediate illness or death. As a general rule, acute toxicity research can only be performed on animals.
Kimbrough said her rat studies also revealed that PCBs do not have a high acute toxicity, although large doses of PCBs did result in liver cancer.
In her career, Kimbrough has published 10 to 15 scientific papers on PCBs. Within the past decade, she has written several review papers critiquing other scientists' research on PCB links to neurodevelopmental, liver, thyroid and other damages. Her own study of the GE workers has also been criticized in the scientific literature, she said.
Kimbrough's cross-examination by plaintiffs' attorneys will begin this morning.
