There is insufficient data available to evaluate residues of plant protection products found in genetically modified plants that are tolerant to certain herbicides, as compared to those found in conventionally grown varieties. Food safety is ensured in the EU through regulation for pesticide residues, which is identical for genetically modified and conventional crops.
This is the main finding in a report from the Norwegian Scientific Committee for Food and Environment (VKM).
VKM’s report was to identify whether differences between the ways of cultivating and using pesticides for genetically modified herbicide-tolerant (GMHT) plants and conventional plants pose a risk to consumers. The project has focused on the use of glyphosate, the most widely used herbicide in the world, in cultivation of both glyphosate-tolerant and conventional varieties of maize, soybean and oilseed rape (Canola).
Results
Insufficient data was available in order to make meaningful comparisons of residue levels of plant protection products in conventional and glyphosate-tolerant varieties of maize, soybean and oilseed rape.
There was insufficient data to conclude whether specific genetic modifications used to break down glyphosate could also react with and influence other plant protection products, e.g. insecticides.
Due to the lack of data, it is not possible to assess whether differences in residues of plant protection products in glyphosate-tolerant and conventional plants are of significance to consumers.
The report also describes practices for cultivating and using plant protection products, for both conventional plants and GMHT plants. Examples are from the USA, South America, and Australia.
In addition to differences in how plant protection products are applied, the shift to cultivating GMHT plants also facilitates new tilling options of the cropland that are important for soil quality.
After the commercialisation of glyphosate-tolerant crops in the mid 1990’s, the use of glyphosate has increased substantially. Annual usage of glyphosate increased almost 15 fold during a 20-year period, reaching approximately 826,000 tons worldwide in 2014.
Initially, after glyphosate tolerant plants were introduced, the use of other herbicides declined, e.g. in the cultivation of maize and soybean. This trend seems to have reversed during the last decade. Several studies have shown increased use of non-glyphosate herbicides in glyphosate-tolerant crops in recent years. This trend, linked to the development of glyphosate-resistant weeds, has resulted in farmers using other herbicides than glyphosate.
Glyphosate:
Most widely used herbicide in the world. Glyphosate works on most plants and is used to kill annual broadleaf weeds and grasses that compete with crops. Glyphosate inhibits an enzyme found in plants, essential to the biosynthesis of amino acids.
Plant protection product:
A chemical or other substance used to protect plants and plant products in agriculture, forestry and horticulture from attacks by fungi, insect pests and competing plants.
GMHT (Genetically Modified Herbicide-Tolerant):
Plants genetically modified to withstand high levels of one, or several, herbicide(s).
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