GM Crops: The First Ten Years - International Service for the ...

GM Crops: The First Ten Years
c) Building on this theme of the impact of the technology to lower real soybean prices, some
(limited) economic analysis has been undertaken to estimate the impact of GM technology
on global prices of soybeans. Moschini et al (2000) estimated that by 2000 the influence of
GM soybean technology on world prices of soybeans had been between -0.5% and -1%,
and that as adoption levels increased this could increase up to -6% (if all global production
was GM). Quam & Traxler (2002) estimated the impact of RR soybean technology adoption
on global soybean prices to have been -1.9% by 2001.
4 The environmental impact of GM crops
This section examines the environmental impact of using GM crops over the last ten years. The
two key aspects of environmental impact explored are:
a) Impact on insecticide and herbicide use.
b) Impact on carbon emissions.
These are presented in the sub-sections below.
4.1 Use of insecticides and herbicides
The most common way in which changes in pesticide use on GM crops has been presented is in
terms of the volumes (quantities) of pesticides applied. Whilst comparisons of total volumes of
pesticide use in a crop production system can be a useful indicator of environmental impacts, it is
an imperfect measure because:
• different active ingredients and amounts may be applied in GM or conventional systems;
• the environmental behaviour and toxicity profile of individual pesticides varies.
To provide a more robust measurement of the environmental impact of GM crops, the analysis
presented in the sub-sections below includes both an assessment of pesticide active ingredient
use, as well as the assessment of the specific pesticides used via an indicator known as the
Environmental Impact Quotient (EIQ). This universal indicator, developed by Kovach et al (1992 &
updated annually), effectively integrates the various environmental impacts of individual pesticides
into a single 'field value per hectare'. This provides a more balanced assessment of the impact of
GM crops on the environment as it draws on all of the key toxicity and environmental exposure
data related to individual products (as applicable to impacts on farm workers, consumers and
ecology) and hence provides not only a consistent but a fairly comprehensive measure of
environmental impact. Readers should however note that the EIQ is an indicator only and therefore
does not take into account all environmental issues/impacts.
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