Agriculture Reference
In-Depth Information
biodiversity losses. The primary concern centres on the adoption of
herbicide-tolerant crops that result in the increased use of broad-spectrum
herbicides. Such products offer the option of a 'complete weed kill', which
is good for the crops, but particularly bad for farmland plants, mammals
and birds. The trend towards clean fields with no weeds, and thus no
herbivorous insects or seed production (which, in turn, comprise food for
birds and mammals), has been a major factor in the decline of farmland
birds. 16 Once again, however, much depends upon the detailed agronomy
and goals of farmers. Some genetically modified organisms could lead to
greater biodiversity. Recent research shows that glyphosate-tolerant sugar
beet can reduce annual input costs from UKĀ£230 per hectare (not
counting the company's technology fee), with farmers able to leave weed
control until at least the four-leaf stage, thus making beet plants harder
for aphids to find and encouraging beneficial predators. This precise
control of weeds during the time when they pose a real threat to yields
could also give the option of greater tolerance of weeds at other times,
thereby leading to biodiversity benefits. At the same time, however,
glufosinate ammonium-tolerant sugar beet has been shown to allow
virtually complete removal of all weeds using less herbicide than a
conventional crop would require. In the US, detailed studies have shown
that some farmers with herbicide-tolerant soyabeans are surprisingly using
two to five times more herbicide than conventional growers. 17
Allergenic and immune system reactions to new
substances
Since transgenes result in the manufacture of new products in crops,
usually proteins, a risk to humans arises if these products provoke an
additional allergenic or immune response. Conventional non-genetically
modified foods already contain a large number of toxic and potentially
toxic products. As a result, the key question is whether a specific genetically
modified organism could result in a new hazard. As 90 per cent of food
allergens occur in response to proteins found in eight foods, namely
peanuts, tree nuts, milk, egg, soyabean, shellfish, fish and wheat, it could
be argued that as genetic modification involves transfer of a single or a
few genes, so it is easier to test for allergenicity. One product, genetically
modified soya with a brazil nut gene, was withdrawn from development
because of potential allergenic effects. 18 The greatest controversy has
surrounded the case of genetically modified potatoes containing lectin and
their effect on rats. Immune response effects have been claimed, but the
research has been widely criticized. If the research had, indeed, shown an
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