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Issues
Key Documents
Overview
Issue 1: Direct effects on biodiversity
and the environment
Issue
2: Indirect effects on biodiversity and the environment
Issue 3: Adequacy of methods for assessing
environmental effects
Issue 4: Characterization and utilization
of biodiversity
Note: For all references cited within this chapter,
direct links are provided to the appropriate section of the Annotated
Bibliography
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Issues
Four
issues are important in assessing the effects of modern genetics on biodiversity
and the environment. These are:
·
Direct
effects on the environment, that
may result from
the release of genetically/ living modified organisms into the environment;
·
Indirect
effects that
may result from
changes in agricultural practices, as a result of the applications of modern
genetics in agriculture and the environment;
· Adequacy
of the methods used to assess the impact of modern
genetics on the environment;
· Usefulness
of molecular methods in the characterization,
conservation and use of biodiversity.
The
areas of scientific convergence, divergence and gaps in knowledge are summarised
in Table 4.1. Their
implications are discussed below.
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Key
Documents
The
environmental issues have been examined in detail in several specialised studies
published by international agencies (e.g. European Commission, EC
2001a;
European Environment Agency, Eastham and Sweet, 2002; OECD
2001b;) and
national agencies (e.g. US NRC 2000; US NAS 2002; CAST 2002; US NCFAP
2002).
Environmental issues also form an important component of several broader studies
by national agencies (e.g. Belgium, VIB 2001; Canada Royal Society 2001; CBAC
2001, 2002; France, Academies des Sciences 2002; New Zealand
2001).
The
environmental risks associated with the release of genetically modified crops in
the environment have also been reviewed by Cook, and by Johnson, in CGIAR
2000a; Dale et al 2002; Nap et al
2003; and Conner et al 2003.
The risks and benefits of specific cases have been reviewed for Bt
cotton (ISAAA 2002 and Pray et al
2002) and other Bt crops (Shelton et
al 2002). The possible effects of genetically engineered corn on the
Monarch butterfly are discussed in several publications by the US National
Academy of Sciences (e.g. Zangerl et al
2001), and also by Shelton
and Sears 2001; and the Pew Initiative 2002). The specific
issues associated with the possible release of transgenic fish into the
environment have been reviewed by the Pew Initiative
(Pew 2003).
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Overview
Agriculture
affects the environment.
New genetic technologies that are used in agriculture will affect the
environment. Their environmental
effects may be either positive or negative. They may either accelerate the
environmentally damaging effects of agriculture, or they may contribute towards
more sustainable agricultural practices and the conservation of natural
resources. It is a matter of
application and choice.
The
environmental effects will depend on the specific genetic application, the
agricultural system and the environment (agro-ecosystem) in which it is used.
Environmental impact needs to be assessed on a case-by-case basis, taking
account of specific risk factors. The
environmental effects of specific technologies may be either direct
effects of a specific trait/species combination on biodiversity, habitats,
landscape, and/or other components of the environment; or they may be indirect
effects,
resulting from changing agricultural practices leading to more, less or
different use of pesticides or herbicides, and/or changing land uses.
In
assessing direct and indirect environmental effects, new biotechnology-based
technologies need to be compared with present agricultural practices, and other
technology options. Comparison with base line ecological data is also desirable,
but is difficult to obtain in many instances. Also, both the risks and the
benefits of new technologies need to be considered, so as to develop a picture
of the options available and the choices implied.
The
potential environmental impacts of modern genetics may be thought of in a
hierarchical manner, from consequences for the crop (or other genetically
modified species) and its relatives, through to interactions at the community
level, and at the ecosystem level.
Small
or large genetic modifications may perturb the environment. It is difficult to
extrapolate from the environmental impact assessments of the first generation of
genetically modified crops (that are mainly the result of single gene
modifications for pest or disease resistance) to emerging products that may be
the result of genetic modifications to regulate more complex traits. For
example, future traits in plants may be changes in tolerance to abiotic and
biotic stresses, altered nutritional content (eg vitamins, oil, starch) and/or
modified biochemical pathways to produce compounds for medical or industrial
uses (US NAS 2000).
Environmentally
friendly product design
The
greater understanding of the environmental risks and benefits posed by modern
genetics may lead to the better design of future crops. For example, where gene
flow is a risk in out-crossing crops growing in their centre of diversity, close
to wild relatives with which they may cross, it may be possible to include
genetic mechanisms of pollen incompatibility to limit the risk of gene flow.
Also the increased availability of tissue specific promoters enables genes to be
expressed only in the part of the plant where required (e.g. leaves) and not in
the pollen or other pars of the plant, thus reducing the risk of inadvertent
gene transfer.
Where
crops are to be used for industrial purposes to produce products such as
vaccines, or industrial polymers, the crop of choice should be one with which
there is no risk of gene flow to related edible crops or wild species in the
area of cultivation (Johnson in CGIAR 2000a).
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Issue
1: Direct effects on biodiversity and the environment
Modern
genetics is being used in the improvement of crops, trees, livestock, fish and
microbial species used in agriculture. Each may have direct effects on the
environment.
Plants:
Several
issues need to be considered in relation to the cultivation of plants in the
environment. These are the potential for:
·
Gene
transfer, the movement of genes from a cultivated
crop through pollen out-crossing to form hybrids with local landraces and/or
related wild species.
·
Weediness,
the tendency of plants (or their derived hybrids/backcrosses formed with related
or wild species) to spread beyond the field where first planted and become
established as a weed amongst crops or invasive species in other habitats.
·
Trait
effects, the
effects of specific traits that may be potentially harmful to non-target
organisms and damage their role in ecosystem function.
·
Expression
of genetic material from pathogens, such
as virus vectors.
·
Unexpected
effects, due to genetic and phenotypic variability, and
the tendency of the plant to exhibit unexpected
characteristics after genetic recombination.
·
Worker
safety upon
exposure to new products.
These
risk issues for the release of plants into the environment are similar in kind,
whether the plants are the result of traditional crop improvement or modern
genetics, or they result from the introduction or escape of ornamental crops.
Trees: There are
potentially direct environmental effects from the release of genetically
modified trees into the environment that are similar to those affecting plants.
There are also added concerns, given the long life cycle of trees.
Microorganisms: The use
of microorganisms in food production is usually in contained situations, such as
fermentation processes. There is also potential for their use in the
environment. For example, specifically designed, genetically improved
microorganisms may be released into the environment as biological control agents
against diseases, pests and weeds.
Fish:
The possible release of genetically modified fish into aquatic environments pose
another distinct set of issues, which also need to be assessed on a case by case
basis (Pew 2003). A key issue is the potential ability of transgenic fish
to cross with, and out compete wild populations.
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Issue
2: Indirect effects on biodiversity and the environment
Changing
agricultural and environmental practices
Indirect
environmental effects may result from changing agricultural and/or environmental
practices that result from specific applications of modern genetics, including
the use of living modified organisms with particular traits. For example:
Pesticide use:
The use of GM crops with insect resistance (Bt
crops) is reducing the volume and frequency of pesticide use on cotton, corn and
soybean (Carpenter et al, CAST 2002). Bt
cotton crops are also having demonstrable beneficial effects on human health and
the environment in China, Australia and South Africa (Pray et al
2002; ISAAA 2002a) by reducing exposure to chemical pesticides.
Herbicide use: The
expanding use of pesticides (including herbicides) has been a major cause of the
decline in farmland birds, arable wild plants and insects in the UK as suitable
habitats disappeared. The more widespread use of broad-spectrum herbicides in
the UK as a result of the cultivation of herbicide tolerant crops (such as
oilseed rape and sugar beet) may accelerate this trend (Johnson in CGIAR
2000a).
Land use: The
future development of new crops with improved tolerance to abiotic factors (such
as drought, salinity and frost) and the advent of crops that may be used to
produce vaccines and/or industrial products may also change crop management and
land use practices. These trends may be either environmentally beneficial or
damaging, depending on the particular crop/trait/environmental situation.
Crops
with tolerance to abiotic stresses may increase pressure on natural biodiversity
when crop cultivation extends into marginal lands, or into areas not presently
used for agriculture. For example, salt tolerant rice may be able to be
cultivated in coastal areas where mangroves presently grow, with resulting
ecological changes in land and water use and associated plant and marine life.
Gene technology may also be used in environmental remediation, for
example in the removal of toxic compounds from soil.
Environmental
benefits of genetically modified crops
Biotechnology-derived
crops provide options and potential solutions for a number of challenges in
modern agriculture. The extent to which they may be the preferred option depends
on many economic, social, and regional factors. Several general conclusions
about the environmental benefits of biotechnology-derived soybean, corn, and
cotton have been documented by studies in the USA and elsewhere (CAST
2002). These
studies concluded:
·
Biotechnology-derived soybean, corn, and cotton provide
insect, weed, and disease management options that are consistent with improved
environmental stewardship.
·
Biotechnology-derived
crops can provide solutions to environmental and economic problems associated
with conventional crops including production security (consistent yields),
safety (worker, public, and wildlife), and environmental benefits (soil, water, and
ecosystems).
·
Although not the only solution for
all farming situations, the first commercially available biotechnology-derived
crops provide benefits through enhanced conservation of soil and water,
increased beneficial insect populations and improved water and air quality.
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Issue 3: Adequacy of
methods for assessing environmental effects
Areas
of convergence
There
is broad agreement that there needs to be science-based environmental impact
assessments of the risks posed by the release of genetically modified crops and
other living modified organisms into the environment.
The
types of risks posed by the release of LMOs into the environment are similar in
kind to those posed by the release of other biological products for agricultural
purposes (e.g. improved crop varieties, biological control agents). This
experience provides a basis for developing risk assessment methodologies for
assessing the risks posed by LMOs, in comparison with their conventional
counterparts.
Areas
of divergence
Interpretation
of data: The types of data sought by regulators for environmental impact
assessments are similar. The differences lie in the interpretation of the data
and identifying what constitutes an environmental risk, and/or an
environmentally damaging effect.
There
is also divergence as to the appropriate basis for comparison for LMOs.
Should this be comparison with present agricultural systems, and/or with
base line ecological data? Ecological data is not widely available as a basis
for risk assessment.
Laboratory
and field scale ecological studies:
There is a lack of agreement as to the value of (small-scale) laboratory
experiments, and their extrapolation from small-scale to large-scale effects.
For example, Monarch butterfly larvae were reportedly damaged when exposed to
pollen from Bt corn plants in laboratory experiments but subsequent field
studies showed their populations were unlikely to be affected by Bt
corn in the
field (Shelton and Sears, 2001; Zangerl et al
2001).
Monitoring
of products post-release is important for environmental stewardships of new
products, and to delay the development of resistance in the target pest
population.
International
harmonization of methodologies and standards:
In contrast to food safety and human health, where the FAO/WHO Codex
Alimentarius commission provides an international forum for developing food
safety guidelines for GMOs for human consumption, there are no internationally
agreed guidelines and standards for assessing the environmental impacts of
LMOs.
Gaps
in knowledge
Gene
flow: Much
debate continues to focus on gene flow between genetically modified crops and
other species in the environment and on the extent to which this may lead to
environmentally damaging effects, such as new weeds. To assess gene flow, when
plants with which genes might be exchanged in the environment are present, more
knowledge is often required on the biology and spatial location both of the LMOs
and such plants. To assess the potential impacts of gene flow, the
characteristics of the introduced genes and related altered traits have to be
taken into account. Uncertainty about the implications of gene flow is more of a
concern when there are wild relatives in the environment and most particularly
when such wild relatives are within centres of diversity (OECD
2001b).
It
is possible to construct databases of the biology and location of wild
relatives, landraces and LMOs. Such databases can be used to identify areas
where there is a high or a low probability of introgression following the
release of LMOs, though the predictive ability of such systems for environments
that have not been rigorously mapped needs to be further tested.
Many
experts consider that gene flow per se is not harmful. However,
relatively few empirical data are available on the long-term consequences of
gene flow. Uncertainty about possible consequences of gene flow may be higher
for these potential long term effects than for short term effects. Assessment of
whether flow of particular genes affects fitness, for example, could be done
step-wise, including prospective assessment of wild populations to determine
likely selection pressures and head-to-head fitness comparisons of transgenic
with non-transgenic populations. Assessment might also address whether
mitigation measures could be appropriate and available (OECD
2001b).
Modelling,
including the incorporation of data from geographical information systems may be
useful to predict the likely behaviour of LMOs in different environments (e.g.
to predict possible effects of gene flow and transmission of novel traits to
local land races and wild relatives in centres of crop diversity).
International
and/or regional harmonization
of guidelines for assessing ecological impacts in different ecosystems is
required. Soil ecosystems are the most complex in which to assess changes, and
their significance.
Comparative
analysis is
required of new technologies in comparison with present agricultural practices
and other technology options (e.g. Bt crops compared to pesticide use or organic
agriculture).
Post-release
monitoring of LMOs in the environment: Much data
has been collected on the release of the first generation of GM crops in the
environment (although mainly for a few crops and a limited number of traits in
North America). Such data would be
valuable if synthesised and made available to guide future regulation of GM
crops.
Ecological
research may require additional support by
national governments and international agencies in their efforts to develop
methodologies and undertake field studies on the environmental impact of GM
crops. These assessments should be undertaken using participatory approaches so
as to involve local communities in the evaluation of the risks and benefits of
new technologies. Additional data
could then feed back into risk assessments, so as to inform future decisions on
the decisions on the appropriate technology choices in addressing specific
problems, including the development and management of genetically modified crops
for agricultural purposes.
The
International Organization for Biological Control (IOBC) is developing a series
of guidelines for ecological research on GM crops and other LMOs in the
environment. The draft guidelines are presently being evaluated in different
regions, for their applicability in different environments.
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Issue 4:
Characterization and utilization of biodiversity
Biotechnology
can contribute to the characterization
of biodiversity, through the use of molecular markers.
The better characterization of biodiversity may lead to its improved conservation
and utilization of biodiversity
through greater understanding of the range and location of diversity within a
species.
Gaps
in knowledge
Functional
genomics for gene discovery: New
discoveries in functional genomics are being used to identify useful genes within species, and understanding how better to regulate theses
genes to control useful traits. This approach will place more emphasis on the
control of genes already existing within
species rather than on inter-specific gene transfers, especially those that
require gene movement amongst distantly related species.
Molecular
finger-printing of genetic resources collections
is a tool that could be used to characterize all the accessions in the
international gene banks, such as those held in trust by the CGIAR centres. This
additional genetic data would provide a molecular passport for each accession,
to accompany its taxonomic description, and the geographical location where it
was originally collected.
Also,
molecular fingerprinting of collections would enable them to be monitored for
any inadvertent introduction of novel genes.
For example, Bt genes from commercial corn have been detected in land
races of corn in Mexico, its centre of diversity.
There has been much debate as to whether these genes may also be found in
the maize genetic resources collection held at the International Center for
Maize and Wheat Improvement (CIMMYT) in Mexico.
The availability of molecular fingerprints for all accessions would
facilitate the resolution of these issues.
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New Genetics, Food &
Agriculture: Scientific Discoveries - Societal Dilemmas