The world wide area cultivated with GM crops has increased continuously
over the last ten years, amounting to 90 million hectares in 2005,
which, by comparison, equal the total areas of California, Nevada,
and Utah. Most of these crops are grown in the United States, Argentina,
Brazil, Canada, China, Australia, South Africa, and India.
These crops usually have been modified with either or both of two
traits, i.e. herbicide resistance and insect resistance.
While these traits are of agronomic and environmental importance,
some experimental crops also possess traits geared towards consumer
needs (e.g. high protein contents), which may in some cases
also be combined with other agronomic traits. Moreover, crops with
agronomic traits may find new applications, such as in the control
of parasitic weeds that are sensitive towards herbicides applied
to herbicide-resistant crops or insect-resistant crops with lowered
mycotoxin contaminations caused by less insect infestation and less
concomitant mould infection.
Herbicide and insect resistance traits are likely to influence
the agrochemicals that are used on the crops with respect to quantities
and nature of the chemicals, as well as the timing of applications.
Subsequently, such changes may influence the nature and levels of
residues present in the crops used for human and animal consumption.
In addition, a number of pesticides have recently become generic,
including broad-spectrum herbicides applied to GM crops, which may
be offered in different formulations than the originally approved
proprietary product. This may also have implications for the resultant
residues levels in crops to which these pesticides are applied.
Another issue is the parallel usage of the same herbicides as weed
control agents on GM crops and as crop desiccants (or defoliants)
on conventional crops, i.e. potentially increasing both environmental
and consumer exposure. Further as these herbicides can no longer
be used as desiccant on GM crops, the further use of alternative
chemicals as desiccants or defoliants is necessitated. In addition,
the GM crops themselves may contain newly introduced transgenic
products with pesticidal properties, such as "plant-incorporated
protectants," as regulated by the US EPA. These products may
substitute for other pesticides and may have food safety considerations
of their own.
In addition, the changed use patterns may affect the levels at
which MRLs for residues of the pertinent pesticides in the GM crop
commodities will be set. This raises the possibility of MRL disparities
acting as irritants to trans-national trade in these commodities.
The team is also involved in another IUPAC project on the environmental
impact of altered agrochemical use on GM crops
> see project # 2001-024-2-600
The project will provide a greater attention to these global trends
and especially on the MRLs to be set for residues of the pertinent
pesticides applied on GM crops and commodities destined for the
international trade. Accordingly, the project is to update the information
gathered during the previous project, and to expand on the levels
of residues of agrochemicals in GM crops, as well as the estimated
exposure of humans and animals to these residues, and the MRLs to
be set for the pertinent pesticides in these crops, touching on
the issues of socio-economic importance, including international
harmonization of regulatory thresholds and consumer concerns. In
a broader sense, these data will be considered with regard to potential
risks and benefits of GM crops compared to conventional crops.