- Potential benefits of GM animals might be realized in the near-to-medium
term, such as improved animal production and product quality and novel animal
products. Other applications that might be realized over the longer term include
use of GM animals as bioindicators, for biological control, and for xenotransplantation.
- There may be a variety of genetic and immunological hazards owing to transgene
integration, expression or instability. Anticipated results of ongoing research
and development work on vector design (including use of insulating or boundary
elements and elimination of antibiotic resistance genes) provide the opportunity
to prevent or reduce some safety concerns and thereby proactively design and
produce GM animals that are safer from the outset.
- Xenotransplantation poses benefits for human recipients of cells, tissues
and organs, but also poses hazards to those recipients and to the human population.
These hazards stem from the possibility that pigs and humans might more easily
transmit diseases to one another, and that pigs might serve as hosts for the
evolution of new human pathogens. There is also the possibility that products
from animals developed for xenotransplantation could enter the human food
supply, posing food safety hazards.
- The likelihood of GM animals entering and persisting in the environment
will vary among taxa, production systems, modified traits, and receiving environments.
The spread and persistence of GM fish and shellfish - or their transgenes
- in the environment could be an indirect route of entry of GM animal products
into the human food supply. This is because escaped individuals or their descendants
could subsequently be captured in fisheries for those species. Similar mechanisms
might apply for poultry such as ducks and quail that are subject to sport
or subsistence harvest. Live transport and sale of GM fish and poultry poses
another route for escape of GM animals and their entry into the environment.
- When there is a food safety hazard and a high likelihood of entering the
food supply through the environment, confinement of the GM animals is necessary.
However, current confinement standards for research with GM animals do not
address the commercial production of GM animals.
- Sterility eliminates the potential for the spread of transgenes in the
environment, but does not eliminate all potential for ecological harm. Monosex
triploidy is the best existing method for sterilizing fish and shellfish,
although robust triploidy verification procedures are essential.
- Methodologies exist for post-release detection of GM animals in the environment,
but protocols for applying them need to be developed and validated. A diversity
of ecological methods could be applied for post-release determination of whether
or not GM animals cause environmental harm, but are very challenging to apply.
- The food safety assessment of GM animals and derived products can largely
be performed along the lines that have already been established for the evaluation
of GM plants and derived products for the consumer. This means that the initial
step of the food safety assessment will be a comparative safety assessment
(CSA) of the GM animal with its appropriate comparator, including a food intake
assessment, followed by a full risk characterization.
- As every GM (founder) animal will have a different genetic constitution
with respect to the integration of the genetic construct, the safety evaluation
should be carried out on a case-by-case basis, even if the same genetic construct
was used for the genetic modification. If improved genetic technologies (e.g.
homologous recombination and insulated insertions) should reduce the possibility
of insertional effects in the future, it may become more feasible to come
to more generic approaches for the safety assessment of GM animals and products
thereof.
- A few major differences can be seen when comparing the GM animal to the
GM plant situation. First, the numbers of GM animals derived from a single
GM founder animal will in general be much lower, aquatic species being the
exception, compared with GM plant genetic modification events and numbers
available in subsequent plant generations. This could result in fewer animals
being available for the comparative safety assessment and therefore more background
data will be required for the safety assessment of animals in comparison with
plants where more background data already exist. Data on the natural background
variation in animal tissue constituents will therefore have to be generated.
Second, an additional difference is the omnipresence of natural toxins in
plant products and the very few cases of animal products that have proved
to contain antinutritional substances for the consumer. On the other hand
zoonotic diseases and human pathogens of animal origin are a concern in the
case of GM animals and need to be taken into account.
- A rigorous pre-market safety assessment of foods derived from GM animals
should provide sufficient safety assurance. The use of post-market surveillance
as an instrument to gain information on the potential long-term or unexpected
adverse and beneficial effects of food either GM animal-derived or traditional
should be further explored. Post-market surveillance could be useful in certain
instances where clear-cut questions require, for instance, a better estimate
of food intake, and the nutritional consequences of foods derived from GM
animals or a better estimate of the environmental fate of GM animals and their
transgenes are required.
