WASHINGTON, May 2, 2016 - Glyphosate, the world’s most heavily used herbicide, is unlikely to cause cancer in humans, the Environmental Protection Agency has concluded.

Or has it?

The literature review by the agency’s Cancer Assessment Review Committee was dated Oct. 1, 2015, and labeled as a “final report” but was not posted in the glyphosate registration review docket until April 29. EPA has been evaluating glyphosate for the purposes of re-registration – or approving its continued use –  since 2009. 

In an odd twist, however, EPA removed the carcinogenicity review and 13 other documents from the docket Monday afternoon. An agency official initially said they had been posted online “inadvertently” without being properly vetted for confidential business information.

But in a statement issued late Monday afternoon, EPA said that the documents were “preliminary” and had been removed “because our assessment is not final.” 

“EPA has not completed our cancer review,” the statement said. We will look at the work of other governments as well as work by (the Department of Health and Human Services’) Agricultural Health Study as we move to make a decision on glyphosate. Our assessment will be peer reviewed and completed by the end of 2016.”

EPA continued: “Currently, we are working through some important science issues on glyphosate, including residues of the chemical in human breast milk, an in-depth human incidents and epidemiology evaluation, the International Agency for Research on Cancer (IARC) cancer re-evaluation . . ., and a preliminary analysis of glyphosate toxicity to milkweed, a critical resource for the monarch butterfly. We hope to issue the draft cancer risk assessment for public comment later in 2016.”

It may be hard for EPA to put the genie back in the bottle, however, as the cancer review was online long enough for people to download it and react. The Center for Biological Diversity, for example, put out a press release saying EPA’s “analysis relied heavily on industry-funded studies that have not undergone public scrutiny.”

EPA’s review was prompted by the IARC review in March 2015 that concluded glyphosate “probably” causes cancer in humans. IARC, an arm of the World Health Organization, “concluded that there is limited evidence in humans for the carcinogenicity of glyphosate based on a positive association for non-Hodgkin lymphoma (NHL),” EPA’s review said. “The IARC also concluded that there is sufficient evidence in experimental animals based on significant positive trends for kidney tumors in one study and for hemangiosarcomas in another study in male mice.”

Monsanto, the Missouri-based seed giant that markets glyphosate under the tradename Roundup and also produces seed that is tolerant of the herbicide, has strongly disagreed with the IARC review.

EPA’s public dissemination of its review was quickly touted by the company, which issued its own press release.

“The EPA is the third regulator to publish its conclusion that glyphosate is not a carcinogen as part of a registration review since IARC announced an inconsistent classification in March 2015,” the company said. “The European Food Safety Authority (EFSA) determined in November 2015 that glyphosate is ‘unlikely to pose a carcinogenic hazard to humans.’ Also in 2015, the Canadian Pest Management Regulatory Authority concluded ‘that glyphosate is unlikely to pose a human cancer risk.’ These conclusions by the EPA and the European and Canadian regulatory authorities are based on standard scientific principles and the overwhelming weight of evidence.”

“No pesticide regulator in the world considers glyphosate to be a carcinogen, and this conclusion by the U.S. EPA once again reinforces this important fact,” Hugh Grant, Monsanto’s chairman and CEO, said in the release.

The Center for Biological Diversity, however, said that IARC “used publicly available research for its analysis. Furthermore, the WHO took into account studies on actual products that are available on store shelves, while the EPA ignored those studies to focus solely on studies that tested glyphosate as a single ingredient. Most products containing glyphosate have other ingredients that can make the pesticide more dangerous.”

EPA’s review, posted in the docket, said “the epidemiological evidence at this time does not support a causal relationship between glyphosate exposure and solid tumors. It went on, “There is also no evidence to support a causal relationship between glyphosate exposure and the following non-solid tumors: leukemia multiple myeloma, or Hodgkin lymphoma. The epidemiological evidence at this time is inconclusive for a causal or clear associative relationship between glyphosate and NHL.”

The review also said that “in experimental animals, there is no evidence for carcinogenicity.”

IARC concluded that “there is strong evidence that exposure to glyphosate or glyphosate-based formulations is genotoxic,” EPA noted.

EPA, however, said IARC’s analysis “included studies that tested glyphosate-formulated products as well as studies where the test material was not well-characterized (i.e., no purity information was provided).” EPA said it “did not include such studies in (its) evaluation.”

“The IARC analysis also focused on DNA damage as an endpoint,” EPA said. But “DNA damage is often reversible and can result from events that are secondary to toxicity (cytotoxicity), as opposed to permanent DNA changes which are detected in tests for mutations and chromosomal damage, (such as) chromosomal aberrations or micronuclei induction.

“The studies that IARC cited, where positive findings were reported for chromosomal damage, had study limitations confounding the interpretation of the results. In addition, these positive findings were not reproduced in other guideline or guideline-like studies evaluating the same endpoints. This includes many negative studies cited by Kier and Kirkland (2013) that were considered by CARC (EPA’s Cancer Assessment Review Committee) but were not included in the IARC decision.”


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