How Do GMOs Affect Our Environment?
By Ligia Monzoni
They are toxic to harmless non-target species. Long-term exposure to pollen from GMO (genetically modified organism) insect-resistant maize causes adverse effects on the behavior and survival of the monarch butterfly, America’s most famous butterfly. Few studies on European butterflies have been conducted, but those that have suggest they would suffer from pesticide-producing GMO crops.
Toxic to beneficial insects:
GMO crops adversely affect beneficial insects important to controlling maize pests, such as green lacewings.
The environmental risk assessment under which current GMO crops have been assessed (in the European Union (EU) and elsewhere) considers direct acute toxicity alone, and not effects on organisms higher up the food chain. But these effects can be important. The toxic effects to beneficial lacewings came through the prey they ate. The single-tier risk assessment has been widely criticized by scientists who call for a more holistic assessment.
A threat to soil ecosystems:
Many GMO crops secrete their toxin from their roots into the soil. Residues left in the field contain the active GMO toxin. The long-term, cumulative effects of growing GMO maize are of concern. EU risk assessments so far fail to foresee at least two other impacts of GMO maize:
Risk for aquatic life:
Leaves or grain from GMO maize can enter water courses where the toxin can accumulate in organisms and possibly exert a toxic effect
This demonstrates the complexity of interactions in the natural environment and underlines the shortcomings of the current risk assessment.
Swapping one pest for another:
Several scientific studies show that new pests are filling the void left by the absence of rivals initially controlled by GMO crops. Plant-insect interactions are complex, are hard to predict and are not adequately risk assessed.
GMO herbicide tolerant (HT) crops are generally associated with one of two herbicides: glyphosate (the active ingredient of Monsanto’s herbicide Roundup used with Roundup Ready GM crops, also sold by Monsanto), or glufosinate, used with Bayer’s Liberty Link GMO crops. Both herbicides raise concerns, but many recent environmental studies have focused on glyphosate, which is associated with:
Toxic effects of herbicides on ecosystems:
Several new studies suggest that Roundup is far less benign than previously thought. For example, it is toxic to aquatic organisms such as frog larvae and there are concerns that it could affect plants essential for farmland birds.
Wider impacts may exist. Glyphosate is associated with nutrient (nitrogen and manganese) deficiencies in GMO Roundup Ready soya, thought to be induced by its effects on soil microorganisms
Increased weed tolerance to herbicide:
Weed resistance to Roundup is now a serious problem in the US and South America where Roundup Ready crops are grown on a large scale. Increasing amounts of glyphosate or additional herbicides are needed to control these ‘super-weeds’, adding to the toxicity of food and the environment.
Doull, J., Gaylor, D., Greim, H.A., Lovell, D.P., Lynch, B. & Munro I.C. 2007. Report of an Expert Panel on the reanalysis by Seralini et al. (2007) of a 90-day study conducted by Monsanto in support of the safety of a genetically modified corn variety (MON 863). Food and Chemical Toxicology 45: 2073–2085
Greenpeace European Unit. www.greenpeace.eu