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1. Introduction

Food and food quality is crucial. Given its significance for human and animal health, we investigate whether plant products from a defined geographical region, produced under different agricultural practices are substantially equivalent or not, in terms of quality indicators like nutritional content, elemental characteristics and herbicide/pesticide residues.

By comparing herbicide tolerant (“Roundup Ready”) GM soybeans directly from farmers’ fields, with extended references to both conventional, i.e., non-GM soybeans cultivated under a conventional “chemical” cultivation regime (pre-plant herbicides and pesticides used), and organic, i.e., non-GM soybeans cultivated under a “no chemical” cultivation regime (no herbicides or pesticides used), a test of real-life samples ‘ready-to-market’ can be performed.

Globally, glyphosate-tolerant GM soy is the number one GM crop plant. The herbicide glyphosate is the most widely used herbicide globally, with a production of 620,000 tons in 2008. The world soybean production in 2011 was 251.5 million Metric tons, with the United States (33%), Brazil (29%), Argentina (19%), China (5%) and India (4%) as the main producing countries.

In 2011-2012, soybeans were planted on about 30 million hectares in the USA, with Roundup Ready GM soy contributing 93-94% of the production. Also in the other leading producing countries, this same GM soy dominates the market accounting for 83% and 100% of production, respectively in Brazil and Argentina. Globally, Roundup Ready GM soybeans contributed to 75% of the total soy production in 2011.

The first-generation glyphosate-tolerant GM-soy plant (event 40-3-2), produced and patented by Monsanto Company, has been genetically modified to tolerate exposure to glyphosate-based herbicides during the entire growth season. For herbicide-tolerant GM plants, herbicide co-technology is an integral part of the production system and will always be used by the farmer. However, in early studies of the composition of Roundup-Ready GM soy, the researchers did not spray the tested plants with the recommended herbicide (Millstone, Brunner, & Mayer, 1999). This shortcoming was quickly corrected, and also sprayed GM soybeans were claimed to be substantially equivalent to non-GM soybeans (Harrigan et al., 2007). Still, and surprisingly, even in these studies, the residues of herbicides were not measured.

The concept of ‘substantial equivalence’ (i.e., close nutritional and elemental similarity between a genetically modified (GM) crop and a non-GM traditional counterpart) has been used to claim that GM crops are substantially equivalent to, and therefore as safe and nutritious as, currently consumed plant-derived foods (Aumaitre, 2002). However, we argue that compositional studies that have overlooked (not measured) pesticide residues contain serious shortcomings. Chemical residues, if present, are important because (i) they are clearly a part of a plants composition, and (ii) they may add toxic properties to the final plant product either by itself or by affecting the plant metabolism. This is particularly relevant for herbicide-tolerant varieties.