Industry Evidence on Glyphosate Residues in Crops Inadequate for Regulatory Purposes


Dear Friends and Colleagues

Industry Evidence on Glyphosate Residues in Crops Inadequate for Regulatory Purposes

Glyphosate is the world’s best-selling herbicide and is used in farming, parks, gardening, forestry and wetland management. Genetically modified glyphosate-tolerant crops, of which Roundup Ready varieties are the most common, have been a commercial success.

Independent research has found that glyphosate-tolerant plants accumulate glyphosate residues at unexpectedly high levels. Such findings fundamentally challenge the assumption of substantial equivalence between glyphosate-tolerant varieties and their unmodified comparators. Glyphosate residues have potential to affect plant material composition. Such residues are also passed on to consumers.

Safety assessment is mostly based on testing performed by companies or by researchers working for such companies. A new study has reviewed 15 reports on the compositional analysis of glyphosate-tolerant cultivars, 15 reports from animal feeding studies, and recent data on glyphosate residues in Roundup Ready soybean. Only half of the reviewed industry studies used plant material produced with the application of glyphosate and only one analyzed the material for glyphosate residues. Application of representative dosage of herbicides as well as subsequent analysis of herbicide residues were missing in industry testing of glyphosate-tolerant GM crops.

This implies that central data from compositional analyses, animal feeding studies and overall risk assessment performed by industry and submitted to regulatory bodies as evidence of safety, are not representative of the materials actually produced by farmers and available on the commercial market. In other words, such evidence produced by industry is of insufficient standard for regulatory purposes.

The study calls for new evidence to be brought forward and evidence produced by biotech industry companies to be supplemented with data from independent research. Alternatively, the risk assessments and analyses performed by industry should be competently supervised to ensure both transparency and an overall satisfactory standard of testing.

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Marek Cuhra

Environmental Sciences Europe, 27(1), 1-14


Background: Genetically modified glyphosate-tolerant cultivar varieties have been a commercial success widely known as Roundup Ready plants. As new glyphosate-tolerant varieties are introduced to satisfy agriculture demand, it is relevant to review the scientific evidence that documents the quality and safety of such biotechnology. Assessments of genetically modified glyphosate-tolerant plants are partly based on the reports from laboratory comparisons with non-modified plants (near-isogenic relatives). Such comparative testing is typically performed as analysis of plant material composition and in animal feeding studies. The material for testing is typically produced in test-fields set up as model environments. Most of this research is planned, performed and reported by researchers employed by biotech industry companies.

Perspective: The present paper aims to: (1) review 15 reports on compositional analyses of glyphosate-tolerant cultivars and 15 reports from animal feeding studies, (2) discuss recent data indicating glyphosate residue in Roundup Ready soybean, (3) outline recent developments of cultivars with increased tolerance to glyphosate.

Findings: The reviewed industry studies show methodological flaws: glyphosate-tolerant GM crops are designed for use with glyphosate herbicide. However, glyphosate herbicides are often not applied in test-study cultivation. In the studies where glyphosate herbicides were applied to growing plants, the produced plant material was not analyzed for glyphosate residues. This review has failed to identify industry studies that mention glyphosate residues in glyphosate-tolerant plants. This indicates that questions and evidence of importance for regulatory assessment have been systematically ignored. Independent research has investigated this issue and found that glyphosate-tolerant plants accumulate glyphosate residues at unexpected high levels. Glyphosate residues are found to have potential to affect plant material composition. Furthermore, these residues are passed on to consumers.

Conclusions: Industry studies are not sufficient for regulation. Despite decades of risk assessments and research in this field, specific unanswered questions relating to safety and quality aspects of food and feed from GM crops need to be addressed by regulators. Independent research gives important supplementary insight.

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