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Disputes over the impartiality of an international cancer research agency are flaring again, as documents suggest that a major study’s preliminary data was hidden by a U.S. scientist when reviewing the cancer-causing potential of Monsanto Co.'s Roundup.
News reports June 14 said that Aaron Blair, a retired epidemiologist at the National Institutes of Health’s National Cancer Institute (NCI), told Monsanto attorneys in a high-profile lawsuit that he did not disclose findings of a long-term study of farmers and cancer that could have influenced a 2015 International Agency for Research on Cancer (IARC) finding. IARC found that Roundup is a “probable carcinogen.”
The revelations in Blair’s deposition—first reported by Reuters—are ammunition in the battle the chemical industry is waging to discredit IARC’s cancer evaluations for chemicals. They have also raised questions on the role unpublished information should play in weighing evidence on carcinogenicity.
The dismissal of the Agricultural Health Study’s (AHS) preliminary findings is “tantamount to scientific vandalism,” Scott Partridge, vice president of strategy for Monsanto, told Bloomberg BNA. But another scientist involved in the review disagreed with Monsanto’s assertions and said the unpublished human data may not have swayed IARC’s call.
Since 1993, the AHS has tracked incidences of cancer in more than 57,000 farmers and family members in Iowa and North Carolina. Although the study has produced several peer-reviewed papers on other pesticides and cancer, AHS data on glyphosate—a widely-used herbicide whose safety record is being tried in court—has not been re-evaluated in the scientific literature since 2005. Glyphosate is the main ingredient in Roundup.
Unpublished data from 2013 in the AHS study showed no association with cancer, but Blair did not alert members of the IARC working group about it, he said in a March 20 deposition conducted by Monsanto lawyer Eric Lasker of Hollingsworth LLP in Washington, D.C. Nearly 200 people afflicted with non-Hodgkin’s lymphona allege in a federal lawsuit that Roundup caused their cancer.
NCI spokeswoman Shannon Hatch told Bloomberg BNA that Blair was unable to discuss glyphosate in a larger study on pesticides due to space constraints in the paper. Hatch said NCI has a draft paper on glyphosate that it plans to submit for peer review and could not comment on an estimated publication date.
Journal peer review practices can take months, and sometimes years, to go from submission to publication. But IARC’s requirements to use only publicly available, peer-reviewed data to guide their determinations would have prevented the agency from considering the study, said one of the chairs of the group that evaluated glyphosate.
The additional information from the unpublished studies would not have been usable for IARC’s decision, Ivan Rusyn, a member of one of the member groups that evaluated glyphosate at IARC and a professor at Texas A&M University, told Bloomberg BNA.
Rusyn chaired the group evaluating “mechanistic” data—the biochemical cascade of events that would examine how certain substances might cause cancer. He said the overall strength of the epidemiological data for the link between glyphosate and human cancers was considered limited by IARC. The 2005 published AHS data did not show either a positive or negative association between glyphosate and cancer, while several other population studies conducted in different parts of the world were positive.
The possibility that knowledge of the unpublished AHS data could have played a role in the final determination “is a hypothetical argument” at this point, Rusyn said. The IARC decision “is not based solely on human evidence.”
The NCI findings on glyphosate and cancer were last published in the journal Environmental Health Perspectives. Researchers found no association between glyphosate exposure and cancer incidence overall but found a suggested association with the incidence of multiple myelomas.
IARC should have prodded Blair for information on the AHS study, which is considered one of the most robust population surveys of cancer in agricultural communities, Partridge said.
“They could have encouraged Dr. Blair. They specifically chose not to,” he said.
The American Chemistry Council, which is leading the campaign to change IARC’s cancer evaluation program by pressuring U.S. lawmakers to stem funding to the institution, called for an investigation.
“Today’s revelations lend even greater urgency to the need for fundamental reform of IARC’s Monographs program, and because IARC’s glyphosate monograph is fatally flawed and no longer credible, it should be immediately withdrawn,” ACC President Cal Dooley said in a statement.
IARC responded to the report June 15.
“The IARC Monographs does not base its evaluations on opinions presented in media reports,” the agency said in a statement. “Instead, the IARC Monographs conducts evaluations of the carcinogenicity based on the systematic assembly and review of all publicly available and pertinent scientific studies, by independent experts, free from vested interests.”
To contact the reporter on this story: Tiffany Stecker in Washington at firstname.lastname@example.org
To contact the editor responsible for this story: Rachael Daigle at email@example.com
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