OMAHA (DTN) -- The consensus is the herbicide glyphosate is unlikely to be carcinogenic to humans, based on the scientific data collected by the U.S. Environmental Protection Agency and presented to a scientific advisory panel, or SAP, studying cancer links to glyphosate this week in Arlington, Virginia.
During the first two days of meetings, EPA officials laid out the scientific basis for the agency's decision to the panel of doctors and other scientists. On Wednesday, the panel began receiving public comments.
Though glyphosate was developed by Monsanto, it is off-patent and sold by many agriculture companies as one of the most widely used herbicides in the world.
Glyphosate came to market in 1974, sold under Monsanto's Roundup label for control of perennial and annual weeds in non-crop and industrial areas. Agricultural crops genetically engineered to withstand glyphosate have greatly expanded the use of the chemistry since 1996. Glyphosate is also used in forestry, urban and lawn and garden applications.
One of the most significant developments with the SAP came on Wednesday, as witnesses called into question the research by scientist Christopher Portier, a name that has been central to the debate as to whether glyphosate is carcinogenic.
In July 2015, Portier, one of the co-authors of the International Agency for Research on Cancer report on glyphosate, said in a scientific briefing in London he was convinced glyphosate causes genetic damage that leads to cancer in humans. Many scientists and glyphosate supporters quickly called into question Portier's cancer research for that IARC report.
Witnesses testified this week that Portier admitted some of his research on a glyphosate connection to tumor development was done incorrectly. Witnesses said the methods Portier used tend to exaggerate the significance of rare tumors by as many as 10 times.
Portier has said there were issues with his own conclusions, in a written response to a critique of his work by Dr. Robert E. Tarone, biostatistics director at the International Epidemiology Institute.
Also in 2016, the U.S. House Science Committee questioned the relationship between EPA and Portier, who is a retired official from the Centers of Disease Control. He has worked as a consultant for the Environmental Defense Fund and was listed as an IARC adviser on the glyphosate report. Portier exchanged emails with top EPA officials about EPA's Cancer Assessment Review Committee report that declared glyphosate likely was not carcinogenic. EPA posted that report briefly, then pulled it off its website.
The House Science Committee also stated Portier had written a letter to the European Food Safety Authority regarding its assessment critical of the IARC finding.
Further complicating Portier's ties, his brother Kenneth Portier, a vice president for the American Cancer Society, is on the SAP studying glyphosate.
Kenneth Portier and Eric S. Johnson, professor in the Department of Epidemiology at the University of Arkansas for Medical Sciences in Little Rock, both raised concerns during the SAP Wednesday that the chemical industry is not doing enough to share data and the effects of glyphosate in occupational exposure.
Portier asked a Dow AgroSciences representative if there was information available as to how many people in the United States are involved in manufacturing glyphosate. In addition, Portier said exposure data for agricultural workers may be too low because those workers are covering more acreage than in previous years.
In 2015, the IARC, a World Health Organization agency, concluded glyphosate was "probably carcinogenic."
IARC came under fire as a result of its broad declarations about what is carcinogenic in summary reports the IARC calls "monographs." The agency, for instance, drew scorn in 2015 for a monograph classifying processed red meats such as bacon as carcinogenic.
The IARC's glyphosate finding last year set off a series of reactions. The EPA earlier this year released and retracted a report refuting the IARC's conclusion.
Monsanto has been sued in dozens of cases by people claiming various cancers can be linked back to glyphosate. Nearly every one of those cases filed cite the IARC findings.
Later in the day Wednesday, a number of farmers and agriculture industry witnesses testified. Chemical company representatives reiterated to the SAP that numerous scientific bodies around the world, including The Canadian Pest Management Regulatory Agency, European Food Safety Authority, Japan Food Safety Commission, European Chemicals Agency, New Zealand Environmental Protection Authority and the Australian Pesticides and Veterinary Medicines Authority, have agreed with EPA's findings that glyphosate was unlikely to be carcinogenic.
West Salem, Wisconsin, soybean farmer Kevin Hoyer told the SAP glyphosate has made it possible for him to improve the sustainability of his operation.
"This panel has the potential to make significant changes to every farm in the United States," he said.
"No regulatory agency in the world considers glyphosate to be a carcinogen. Glyphosate allows me to use conservation practices." Before glyphosate hit the market, Hoyer said his farm depended "heavily" on cultivation practices such as tilling.
"When glyphosate became available, it was the fastest-adopted technology of my career," he said. "Organic matter began to improve and yields increased. We need viable tools to sustain our operation."
Hoyer noted that more than 90% of soybeans planted in the U.S. are Roundup Ready, and 70% of U.S. soybean farmers use conservation tillage as a result of better weed control.
Southern Illinois farmer Martin Barbre, a member of the board of directors for the National Corn Growers Association, said glyphosate has allowed him to reduce nutrient runoff by switching more of his operation to no-till.
"I watch use of inputs for environmental reasons and it makes financial sense," he said. "I run a business and glyphosate helps me run the business better. I have no incentive to overuse glyphosate."
The panel is scheduled to continue hearing public comment Thursday and Friday, as well as to address a number of questions they are charged with answering as they relate to the science on glyphosate.
Read the agenda here: http://bit.ly/…
Todd Neeley can be reached at firstname.lastname@example.org
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