Contents - Faperta

Biosafety of Food from Genetically Modifi ed Crops 451
products have a long history of safe use, and a hierarchical approach has been proposed
based on comparing the chemical fi ngerprints of the transgenic crop plant to those of isogenic
parental or closely related lines bred at identical and multiple sites, extended range of commercial
varieties, and downstream processing effects (Noteborn et al., 2000). It is also important
to know the likelihood that some of the statistical differences in a transgenic crop plant
may be false positives due to chance alone or genetic, environmental, and physiological
effects. The levels of antinutrients such as gossypol, cyclopropenoid fatty acids, and afl atoxins
in the seed from the Bt cotton have been found to be similar to or lower than the levels
present in the parent and other commercial varieties. The levels of MDA (malonaldehyde),
proline, chlorophyll, and endogenous ABA (abscisic acid) in the main leaves of the transgenic
and control lines have been found to be similar (Li, 2003). However, there was a fl uctuation
in levels over the years because of climatic conditions. The level of endogenous IAA (indole-
3-acetic acid) in transgenic plants was low during the seedling stages, but increased with
plant age. The activity of SOD (superoxide dismutase) was consistent over the years, being
lowest during the seedling stage. Transgenic Kangchong 931 tobacco had the same 22 fl avor
constituents in its leaves as the nontransgenic NC 89 tobacco (Ding et al., 2001). The differences
in aroma contents and the main chemical components (Cl, total sugar, nitrogen, and
nicotine content) in the leaves were not signifi cant between the two varieties. Transgenic
Kangchong 931 had lower total residues of BHC in the leaves as compared to the conventional
variety, NC 89. Potato tubers of insect- and virus-protected varieties are substantially
equivalent to tubers of conventional potato varieties in terms of total solids, vitamin C,
dextrose, sucrose, soluble protein, glycoalkaloids, fat, ash, calories, total protein, crude fi ber,
vitamin B6, niacin, copper, magnesium, potassium, and amino acids (Rogan et al., 2000). The
information available so far has indicated that there are no substantial differences in chemical
fi ngerprints, secondary metabolites, and nutritional quality of food from transgenic crops
as compared to that of the nontransgenic parental lines.
Biosafety of Transgenic Feed/Forage for Animals
Nearly 75% to 80% of genetically modifi ed crops are used as animal feed. The equivalence in
digestible energy and crude protein between isogenic and transformed plants expressing a
wide range of modifi cations (insect resistance, herbicide tolerance, or barnase/barstar system
of sterility/fertility restoration genes) has been clearly demonstrated in different species.
In none of these experiments was animal performance affected by feeding transformed
plants compared to animals fed control or isogenic plants, whether measured in terms of
growth rate, feed effi ciency, and carcass merit in beef cattle; egg mass in laying hens; milk
production, composition, and quality in dairy cows; or digestibility in rabbits. Laboratory
animals have been used in toxicological studies of the products of introduced genes, but they
are rarely fed the entire transformed plants, or their by-products (Aumaitre et al., 2002).
Despite not being required to or recommended by existing legislation, many new products
have been tested intensively with farm animals to measure effects on performance and animal
health, digestibility of key nutrients, wholesomeness, and feeding value. Detection of
chloroplasts-specifi c gene fragments by polymerase chain reaction has shown the presence
of plant DNA fragments (199 base pairs) in lymphocytes and duodenal juice of the dairy cow,
and in muscle, liver, kidney and spleen of broilers. However, tDNA expressing Bt genes
usually found as a single copy has not been detected in milk, tissues, or eggs in livestock
fed Bt maize.
Transgenic soybean, rapeseed, cottonseed, maize, and whole plant maize are used as
cattle feed/forage (Kosieradzka, 2002). Several studies have confi rmed that their nutritive
value is similar to the isogenic varieties, and no adverse effects on growth and production