By Todd Neeley
DTN Staff Reporter
OMAHA (DTN) -- Despite disagreements among members of a scientific panel reviewing the herbicide glyphosate for cancer connections, the final report of a U.S. Environmental Protection Agency panel concludes there is "no reliable evidence of an association between glyphosate exposure and any solid tumor, or between glyphosate exposure and leukemia or Hodgkin's lymphoma."
The report, generated from a December scientific advisory panel meeting in Arlington, Virginia, was posted on the agency's website Thursday.
It shows disagreement between members of the panel on a number of issues related to the agency's review.
One of the questions the panel was asked to address was: "Whether or not there is the potential of glyphosate-associated NHL (nonHodgkin's lymphoma) risk in exposed humans?"
The report said some panel members believed there is limited, "but suggestive," evidence of a "positive association between glyphosate exposure and risk of NHL from epidemiological studies."
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.
The disagreement comes from differing perspectives panel members had about some medical studies. Those studies, which showed the potential of a correlation between glyphosate and some tumors, didn't satisfy all panelists in that the studies did not adequately separate out other potential cancer-causing agents on the farm. Farm work has long had an unexplained correlation with lymphoma and leukemia that predate high use of glyphosate.
Some of those dissenting panelists recommend EPA revise its conclusion to include the following statement: "Based on the weight-of-evidence from all available data that were abstracted from all qualified human studies, the agency cannot exclude the possibility of observed positive associations between glyphosate exposure and risk of NHL suggesting human carcinogenic potential of glyphosate even though study limitations and concerns about potential biases remain."
Other panelists strongly disagreed, instead backing up EPA's findings that any positive connections between glyphosate and cancers were weak and "confounded by other aspects of living or working on a farm." They also noted that a study involving pesticide applicators, who should have even higher exposure to glyphosate than farmers and therefore more cancers if a correlation exists, also lacked higher incidence of cancers.
The panel's report said that, based on EPA's own guidelines for cancer risk assessment, the conclusion of "suggestive" evidence of carcinogenic potential is considered by "some panel members to be the most appropriate because of the descriptors listed to justify this conclusion."
EPA currently is reviewing the panel's work and is slated to make a decision on glyphosate this year.
The agency currently is scheduled to publish the draft glyphosate human health and ecological risk assessments for public comment in 2017.
According to the report, some panel members recommended a number of ways to improve an EPA issue paper on the glyphosate analysis.
Those panelists recommend the agency re-analyze data from all NHL studies using certain types of analysis.
In addition, some panel members recommend the agency further examine the "suggestive" association of Hodgkin's lymphoma risk and human exposure to glyphosate by using supporting evidence from mouse studies.
"EPA reviewed and analyzed the results of 15 rodent bioassays and concluded that the results as a whole do not indicate carcinogenicity of glyphosate," the report said.
"Some panel members agreed with this conclusion, noting that the issue paper correctly finds the tumor-response data to be too inconsistent to be considered compound-related. Other panel members interpreted the totality of the tumor data as supporting the hypothesis that glyphosate may cause the promotion or progression of common spontaneous lesions. These panel members argued that there is sufficient evidence to conclude that glyphosate is a weak rodent carcinogen and/or tumor promoter.
"Panel members agreed that based on the evidence presented in the issue paper, there is essentially no statistical evidence of an association between glyphosate exposure and any solid tumor, or between glyphosate exposure and leukemia or Hodgkin's lymphoma, even if the possibility that some of the studies reviewed were subject to potential biases is ignored."
When it comes to lung, colorectal and breast cancers, the panel concluded the "availability of epidemiologic data is still extremely limited and prevents more in-depth discussion of those associations."
Oklahoma Republican Sen. Jim Inhofe said in a statement Thursday it was time to renew approval of glyphosate.
"I applaud EPA for posting the science advisory panel report and am not surprised it did not find glyphosate to be carcinogenic," he said.
"I now encourage EPA to quickly reauthorize the use of glyphosate as an herbicide. This product is essential to Oklahoma's farmers, who use it to ensure American-produced food remains both abundant and affordable."
Also this week, the European Chemicals Agency, or ECHA, concluded that glyphosate is not carcinogenic, http://bit.ly/….
In addition, the U.S. District Court for the Northern District of California unsealed a number of documents in a lawsuit filed against Monsanto Co. That lawsuit alleges company employees served as ghost writers on two studies EPA relied on for reaching its conclusion.
In September 2016, the EPA posted to its website the issue paper titled, "Glyphosate Issue Paper: Evaluation of Carcinogenic Potential," a 227-page document outlining the voluminous studies examined by EPA.
In May 2016, EPA posted and then removed from its website a final report from the agency's Cancer Assessment Review Committee, or CARC, that essentially cleared glyphosate. The agency said the report was posted inadvertently, but it caused further political and public-relations problems for the agency.
Read the scientific advisory panel's report: http://bit.ly/…
Todd Neeley can be reached at todd.neeley@dtn.com
Follow him on Twitter @toddneeleyDTN
(GH/AG)
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