Abstract
Glyphosate-tolerant (GT) soybeans dominate the world soybean market. These plants have triggered increased use of, as well as increased residues of, glyphosate in soybean products. We present data that show farmers have doubled their glyphosate applications per season (from two to four) and that residues of late season spraying of glyphosate (at full bloom of the plant) result in much higher residues in the harvested plants and products. GT soybeans produced on commercial farms in the USA, Brazil and Argentina accumulate in total an estimated 2500–10,000 metric tonnes of glyphosate per year, which enter global food chains. We also review studies that have compared the quality of GT soybeans with conventional and organic soybeans. Feeding studies in Daphnia magna have shown dose-related adverse effects (mortality, reduced fecundity and delayed reproduction) of glyphosate residues in soybeans, even at glyphosate concentrations below allowed residue levels. We argue that GT soybeans need to be tested in fully representative and realistic contexts. However, the current risk assessment system has only required and received data from field trials with beans that were sprayed with much lower doses of glyphosate as compared to contemporary commercial farms. This has left knowledge gaps and a potentially serious underestimation of health risks to consumers.
Highlights
Glyphosate-tolerant (GT) soybeans dominate the world soybean market
Early safety studies funded by industry in 1995–1998 concluded that GT soybeans and other herbicide tolerant genetically modified (GM) crops were ‘substantially equivalent’ to ordinary varieties, those studies had major flaws, e.g., the plant material was cultivated in artificial conditions in test-fields without spraying with the herbicides that farmers used in commercial production [10,17]
Showed that identically sprayed GT soybean grown in fields with a history of glyphosate/glyphosate-based herbicides (GBHs) use had residues twice as high as plants grown in soil without a history of glyphosate use, indicating that glyphosate accumulates in the soil and can be absorbed into subsequent crops
Summary
Glyphosate tolerant (GT) soy deserves sustained attention from researchers and regulatory authorities because several safety issues have not yet been resolved It is the dominant genetically modified (GM) plant and trait combination on the global market. About 77% of the global soybean production comes from GT soybean and the dominant soy producing countries of Brazil, USA and Argentina have a 94%–100% adoption rate of ‘biotech crops’, mostly glyphosate tolerant varieties [1]. This development in agro-industrial technology has been reported to have contributed to increased gross farm incomes mainly by reducing production costs [2]. 1995, in which herbicides are sprayed directly on the plants during the growing season, makes the issue of glyphosate residues in the food chain increasingly relevant
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