Roundup is the most widely used herbicide worldwide. The majority of GM crops have been modified to tolerate Roundup, the main chemical ingredient of which is glyphosate. GM glyphosate-tolerant plants are engineered to absorb the Roundup herbicide without dying, meaning that GM glyphosate-tolerant crops may contain glyphosate residues.
Roundup is not only used on GM crops. It is also used for:
- Desiccating (drying down) crops to make them easier to harvest and to enable storage without rotting
- Weed control for a variety of crops
- Weed control by municipal authorities in public spaces, such as on roadsides, pavements, railway lines, parks, and school grounds
- Weed control in home gardens.
Thus, irrespective of GM crops, the impacts of Roundup on its own warrant evaluation.
Commercially available Roundup herbicide contains both glyphosate – the so-called active ingredient – and added ingredients (adjuvants) to make the herbicide more effective. These include surfactants or wetting agents, which help the glyphosate penetrate the plant.
These adjuvants are called “inerts” by the industry and regulators. However, biologically, they are not all inert. Studies show that adjuvants can be more toxic than glyphosate alone and they can increase the toxicity of glyphosate. As a result, complete herbicide formulations like Roundup are far more toxic than glyphosate alone.
However, the safety tests conducted by industry to support regulatory authorizations of glyphosate herbicides are on glyphosate alone. The complete formulation of Roundup as it is sold and used has never been tested over the long term for regulatory purposes. Séralini’s study contributes valuable data to this information vacuum.
 Bøhn T et al (2013). Compositional differences in soybeans on the market: glyphosate accumulates in Roundup Ready GM soybeans. Food Chemistry. 18 Dec. http://www.sciencedirect.com/science/article/pii/...
 Mesnage R et al. (2012). Ethoxylated adjuvants of glyphosate-based herbicides are active principles of human cell toxicity. Toxicology 313(2–3):122–128.