In an opinion published on the eve of the European Commission’s possibly final discussion over whether to extend the registration of glyphosate for a further 15 years, the United Nations’ Food and Agriculture Organization (FAO) and the World Health Organization (WHO) in a joint statement said the pesticide ingredient is "unlikely to pose a carcinogenic risk to humans" exposed to it through food.

Glyphosate is the main ingredient in US agribusiness giant Monsanto’s Roundup Ready GMO seed program. After reviewing the scientific evidence, the 18-member Joint Meeting on Pesticide Residue that took place at WHO headquarters in Geneva, Switzerland, from May 9- 13 said it also had concluded that – like glyphosate –two other pesticide ingredients, diazinon and malathion , are unlikely to be genotoxic in humans.

All of the evaluations were focused solely on cancer. The volume of literature dealing with pesticide exposures and non-cancer outcomes (neurodevelopmental, neurodegenerative and reproductive outcomes, among other health outcomes) was not within the scope of the Meeting.

For glyphosate, the experts reaffirmed their previously recommended acceptable daily intake (ADI) of 0-1 mg per kg of body weight. At the same time, they said that, based on the tests reviewed, the “overall weight of evidence indicates that administration of glyphosate and its formulation products at doses as high as 2000 mg/kg body weight by the oral route is not associated with genotoxic effects.”

This was also said to be the case when considering the evidence from several available epidemiological studies on cancer outcomes following occupational exposure to glyphosate. The evaluation of these studies focused on the occurrence of Non-Hodgkins-Lymphoma (NHL). 

For glyphosate as well as malathion, the Meeting acknowledged some positive association with a risk of NHL from the case control studies and the overall meta-analysis but said “the only large cohort study of high quality found no evidence of an association at any exposure level.”

Malathion has been extensively tested for genotoxicity, including studies in exposed workers, the experts noted, adding that there are “numerous reports” that chemical can induce oxidative damage in cells. But based on the results of animal bioassays, genotoxicity assays and epidemiological data, they believe “malathion and its metabolites are unlikely to pose a carcinogenic risk to humans from exposure via the diet.” Here, the Meeting reaffirmed the ADI of 0-0.3 mg/kg body weight.

“No contradiction” of IARC findings

The FAO/WHO panel acknowledged that its conclusions may appear to contradict a finding by the WHO's International Agency for Research on Cancer (IARC) in March 2015, which said glyphosate is “probably" able to cause cancer in humans and classified the chemical as a 'Group 2A' carcinogen. At the same time, it said it saw no contradiction between the two opinions, which were "different, yet complementary.”

The assessment made seven months ago by IARC, which is based in Lyon, France, focused on the hazards of the product glyphosate while the more recent review other looked at exposure risk.

"IARC reviews published studies to identify potential cancer hazards," the WHO explained in a question-and-answer paper. "It does not estimate the level of risk to the population associated with exposure to the hazard.” The committee, it said, looked at both published and unpublished studies to assess the health risk to consumers from dietary exposure to pesticide residues in food.

The European Food Safety Authority (EFSA), as well as the US Environmental Protection Agency (EPA), have concurred in the past that glyphosate has low toxicity for humans.

Later this week, the European Commission’s pesticides committee is due to meet to decide whether to renew the registration of glyphosate for 15 more years or a shorter period, as some have advocated. The European Parliament has advocated a renewal for seven years.

Especially since the IARC’s conclusions were published, European consumer and environmental health advocacy groups have been pushing for a ban on herbicides that contain glyphosate and/or 2,4-D.

Ahead of the Commission committee’s meeting, the German Friends of the Earth affiliate, BUND, said it was not surprised by FAO/WHO’s latest conclusion, as its previous reports in 2004 and 2015 had said the same thing. Pointing to persisting difference of opinion between the WHO’s pesticides and cancer research arms, the environmental advocacy group said the latest announcement indeed does contradict the IARC evaluation.

Monsanto has demanded a retraction of IARC’s classification of glyphosate, while Dow Chemical is fighting an appeal by the EPA to the US Federal Trade Commission over the chemical producer’s genetically manipulated Enlist Duo corn and soybean herbicide containing both glyphosate and 2,4-D.

In November, 2015, EPA said it would ask a federal appeals court to vacate the agency’s own approval of Dow’s herbicide Enlist Duo to give it more time to evaluate new information regarding the product’s toxicity to neighboring crops.