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Key Documents
The
issues in relation to food safety and human health have been examined in
detail by several international agencies (e.g. FAO/WHO 2000, 2001a, 2001b; IUNS/IUTOX
2002; OECD 2000a,b; OECD 2001a). Similarly, there are
several recent studies by national agencies (e.g. Belgium,
VIB 2001; Canada, Royal Society 2001, CBAC 2002;
New Zealand 2001; UK Royal
Society 2001; US Society of Toxicology 2002).
The science underpinning
these issues is also discussed in reviews by Kuiper
et al 2001 and Lehrer,
in CGIAR 2000a.
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Overview
Issue
1: Safety of genetically modified foods for human consumption
Presently
available genetically modified foods are safe to eat.
GM foods presently on the market have been assessed for any risks of
increased allergenicity, toxicity, or other risks to human health, using
internationally agreed food safety standards. Food safety assessments in
several countries have deemed these foods to be as safe as their
conventional counterparts. This is the consensus view of several reports by
national and international agencies (eg FAO/WHO 2000, 2001a,
b; IUNS/IUTOX 2002; UK Royal Society
2001; US Society of Toxicology 2002).
Further,
there is no evidence of any ill effects from the consumption of foods
containing genetically modified ingredients so far. The dietary consumption
of additional DNA from plants, viruses or bacteria poses no additional risks
to humans, as the human diet already contains much DNA of plant, microbial
and animal origin. Since GM crops have first been cultivated commercially in
1995, many millions of meals have included GM ingredients (mainly coming
from maize, soybean and oilseed rape, grown in North America and Argentina),
without any reported adverse effects (OECD 2000a).
The
lack of demonstrated ill effects to date does not mean that risks do not
exist as new foods are developed with novel characteristics. Food safety
assessment strategies need to be determined on a case-by-case basis,
using scientifically robust techniques, to ensure that foods that are
brought to market are safe for consumers. The extent of risk assessment
should be proportionate to the likely risks (Kuiper et al
2001).
Regulatory
processes need to be sufficiently flexible so as to be able to detect early
warning of changing circumstances. Recent instances of food safety
problems in several countries (eg with BSE, E.coli contamination, and
toxic chemicals in food) highlight the need for continuing vigilance in
ensuring that foods brought to market are safe to eat, irrespective of their
source and production methods. These foods may come from intensive or
subsistence agriculture, organic agriculture and/or the cultivation of GM
crops.
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Issue
2. Food Safety Assessment Methods
Areas
of scientific convergence
Present
methods:
The United Nations Food and Agricultural Organization (FAO) and the
World Health organization (WHO) maintain an overview of the methods used to
assess the safety of GM foods (through Codex Alimentarius, an
inter-governmental commission with 162 member countries).
The FAO/WHO
2000 consultation
concluded that: “The Consultation was satisfied
with the approach used to assess the safety of the genetically modified
foods that have been approved for commercial use.”
Improving methodologies for assessing future product
safety: New scientific developments are being
used to develop improved methods of risk assessment, so that the risks and
benefits of possible future GM foods can be adequately assessed.
For example, new profiling methods are being developed to assess the
full content of whole foods, as distinct from measuring the levels of
targeted single compounds in foods. Such new methods may be useful to detect
any unintended compositional changes in foods as a result of genetic
modification (Kuiper
et al 2001). Such unintended
changes may occur during conventional plant breeding as well as through gene
technology.
Possible
new risks in novel foods: New approaches to
food safety testing are of particular interest for assessing the safety and
nutritional significance of future GM foods and crops that are being
developed for potential improvements in their nutritional qualities, such as
increased vitamin or mineral content or modified oil or starch content
(IUNS/IUTOX
2002).
Areas
of scientific divergence
Substantial
equivalence
“The
concept of substantial equivalence is a starting point for safety evaluation
and contributes to an adequate food safety assessment strategy” (OECD
2000b).
Safety
assessments of GM foods compare
the properties of the new food with those of its traditional counterpart.
This comparative approach, applying the principle of substantial equivalence,
is based on the assumption that conventional foods are generally considered
as safe for consumption, based on a history of safe use (Figure 3.2).
Any
identified differences between the GM food and its conventional counterpart
are assessed with respect to their safety and nutritional implications for
the consumer. Thus, substantial
equivalence is a conclusion that may be reached after comparative
analysis of a genetically modified food and its traditional counterpart. If
no significant differences are detected by comparison of a selected number
of compounds (a targetted approach), a conclusion of substantial equivalence is reached. If
significant differences are identified, they are used to highlight areas for
further examination to see if there are any food safety concerns that need
to be addressed (eg potential allergenicity) (Kuiper et al
2001).
Opponents
of this comparative approach consider that
non-targetted approaches are
required, which compare the content of whole foods, to better assess both
intended and unintended effects.
Precautionary
approaches
There
are differing views as to whether
a precautionary approach is a useful concept in risk assessment. One of the
limitations of the precautionary approach is that it is not possible to
deliver certainty in biological systems. (See Chapter 5 on regulatory
approaches).
Gaps
in knowledge
Food
safety assessment methods
New methods for safety assessment of whole foods: Comparative
safety assessments may be followed for the next generation of GM foods in
order to establish the degree of equivalence with presently available foods.
The unmodified host organism may function as the relevant comparison for
testing the degree of equivalence. In some instances a safety assessment of
the new (whole) food itself will be necessary.
For example, detailed risk assessments may be required for GM crops
with extensive modification of existing metabolic pathways or addition of
new ones, or for GM plants with decreased levels of naturally occurring
toxins, which previously could not be used as food sources (Kuiper et al
2001).
Safety
testing of whole foods is difficult. Present approaches for detecting
expected and unexpected changes in the composition of GM food crops are
primarily based on measurements of a limited selection of single compounds (targetted approach). In
order to increase the possibility of detecting any unintended effects, new
profiling methods (using gene expression technologies, proteomics and
metabolomics) should be further developed and validated, for a non-targetted
approach. Such new profiling techniques should enable increasingly
comprehensive assessments of compositional changes in food. The principal
problems associated with advanced technologies for the determination of
compositional changes in food lie not in the compositional analyses
themselves, but in assessing the significance of the results of those
analyses (Kuiper et al. 2001; IUNS/IUTOX
2002).
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Issue 3: Benefits
Human
health benefits of genetically modified foods
and crops may result from either direct
effects of genetic improvements on
the content of food, or indirect effects,
through changing agricultural practices and/or beneficial environmental
effects.
For
example, direct health benefits lies
in the potential for introducing traits for:
·
Improving nutritional quality of specific
foods (eg improving vitamin content);
·
Reducing toxic compounds in food (eg
cassava with lower levels of cyanide);
·
Removing
allergens from certain foods (eg peanuts).
Indirect
health benefits may
come from the effects of modern genetics on agricultural practices, through:
·
Pest
tolerant crops able to be grown with lower levels of chemical pesticides,
resulting in reduced residues in food and less pesticide exposure for farm
workers;
·
Disease
resistant crops with lower levels of potentially carcinogenic mycotoxins;
·
Increased
availability of food through higher productivity, with more food being able
to be produced per unit of land and per unit of water;
·
Plants
and microbes able to remove toxic compounds from soil (eg Brassicas
able to remove arsenic compounds from soil).
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Issue
4: Identification of GM Foods in the Market place
Areas
of scientific convergence
“Pre-market
safety assessment of GM foods will need to provide sufficient safety
assurance for consumers” (Kuiper et al. 2001).
Post
market surveillance of the effects of consumption of GM foods is likely to
be difficult, expensive and may not yield useful data, due to the complex
composition of diets and genetic variability in populations. The safety of
particular foods needs to be determined before
they are approved for commercial use, using scientifically robust techniques
that are continually reviewed and improved in the light of advancing
knowledge.
Areas
of scientific divergence
Food labelling
Labelling: A
key issue in food safety for consumers is being able to identify those foods
that may contain allergens and other potentially harmful substances, so that
people who have allergic or food intolerant reactions to particular foods
can avoid them. Others may wish to avoid certain foods on health, ethical or
religious grounds.
Labelling
of foods as GM or non-GM may
enable consumer choice, as to the process
by which food is produced. It conveys no information as to the content
of foods, and whether there are any risks and/or benefits associated with
particular foods. More
informative labelling of foods would disclose the nutrient content of the
food, in relation to similar foods produced by conventional agricultural
practices, as well as any additional protein (or other) content resulting
from the specific genetic modification.
Informative food labelling could enable consumers to make choices
about particular foods, after assessing their risks and benefits.
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New Genetics, Food &
Agriculture: Scientific Discoveries - Societal Dilemmas