Agriculture Reference
In-Depth Information
assessment (EFSA, 2008). It seems to be
nearly impossible from the nutritional point
of view to adapt toxicity studies for testing
whole feed. h e OECD (1998b) guideline has
been developed to assess the safety of
additives and not to test whole feed/food.
h e EFSA (2011b) states that the purpose for
a repeated-dose, 90-day oral toxicity study
on whole food/feed is to reassure the public
that the GM food/feed is just as safe and
nutritious as its traditional comparator. In
such cases, high portions of the whole feed/
food should be supplemented to a basal diet,
knowing that the energy and nutrient
requirements of laboratory animals (NRC,
1995) are not met and imbalances in some
nutrients, especially amino acids, could be
expected (EFSA, 2011b). h is statement
seems to be important from the view of
many GM feeds rich in protein (e.g. soybean,
cotton, rapeseed). It is nearly impossible to
make scientii c conclusions under im balanced
conditions (NRC, 1995). Adjusted diets - if
possible - should be fed under those
conditions.
Another point of criticism of the 90-day
feeding study with rodents is the duration
of the experiments for safety assessment.
Some authors (e.g. Seralini
et al
., 2011,
2012) consider 90 days to be too short for
various parameters such as fertility and
reproduction, histopathology of some
organs (e.g. liver, kidney), hormone status,
etc. h e authors propose 2-year studies
with mature rats or other animals (at least
three species; de Vendomois
et al
., 2009),
which should include sexual hormone
assessment and reproductive, develop-
mental and trans-generational studies.
Details about the expenses of such studies
and the potential scientii c yield, as well the
higher levels of safety, are not given (see
Chapter 8 for long-time and multi-
generation studies). Recently, such a 2-year
study (Seralini
et al
., 2012) with rats was
carried out, with confusing results because
of many weaknesses (e.g. no char-
acterization of the composition of feed-
stuf s and mixed feed, low number of
animals) in experimental design. More
details about the necessity of studies with
laboratory animals and useful end points
have been described by the EFSA (2006,
2008, 2011b) and OECD (1998b).
As already mentioned, the scientii c
output to contribute to the nutritional and
safety assessment of feed for the nutrition
of target species with such studies in
laboratory animals would be very small or
negligible. In some cases, appropriately
designed animal toxicology studies can
provide an additional measure of safety
assurance. In general, however, such studies
in laboratory animals are unlikely to reveal
unintended minor compositional changes
that have gone undetected by targeted
analysis because they lack adequate
sensitivity. Specii c studies with target
animals may contribute more substantially
to the nutritional assessment of feed and
could be useful for safety assessment. h is
conclusion also seems to be very important
from the view of GM feed used in animal
nutrition (see Table 5.2).
Model animals (mice, rats, rabbits) or
small target animals (chicks, quails, piglets)
are also used to measure the digestibility/
bioavailability of nutrients in GM crops (see
Section 5.5.1) because of the high costs and
the limited feed amounts available in some
cases, especially in early plant-breeding
stages (see Chapters 6 and 7 for more
details).
Studies with target animals (food-producing
animals) are focused mainly on nutritional
concerns. Up to now, such studies have paid
less attention to safety aspects (EFSA, 2008,
2011a). Future feeding studies with target
animals should also be used for the safety
assessment of GM plants because of the
high proportion of these plants used for
animal nutrition (see Chapter 1) and the
cultivation of second-generation GM plants
(see Chapters 7 and 12). h e type of studies
depends on the type of genetic modii cation
in the plants or animals and the availability
of GM feed or GM animals.
Animal feeding studies should be con-
ducted in target animal species to
demonstrate the nutritional properties that
