Full Report - Food, Nutrition, and the Prevention of Cancer

Box 4.9.2 ‘Organic’ farming
So-called ‘organic’ farming is essentially a reversion to, or revival
of, methods of agriculture that were the standard until the introduction
of farming systems dependent on chemical fertilisers,
pesticides, and biocides, in the second half of the 20th century.
Organic farming avoids or largely excludes the use of synthetic
fertilisers and pesticides, plant growth regulators, and livestock
feed additives. Farmers tend to rely on crop rotation, crop
residues, animal manures, and mechanical cultivation to maintain
soil productivity, and to supply plant nutrients and control
weeds, insects, and other pests. Organic farming is intended to
be indefinitely sustainable.
This type of farming has become well established within
Europe and is expanding at a steady rate. More than 10 per cent
of farms in Austria, Switzerland, and several other countries use
organic methods.
The retail market for organic farming in high-income countries
has grown about 20 per cent each year since the early 1990s due
to increasing consumer demand. Production and distribution
have become correspondingly large scale. The variety and availability
of processed organic food has increased dramatically, and
the cost — which was initially high — is continuing to fall.
Claims that foods produced by organic methods are biologically
or nutritionally superior to food produced by intensive
methods are not supported by clinical or epidemiological evidence,
but some food compositional data indicates higher concentrations
of some constituents like vitamin C and dietary fibre.
There is evidence that organic products contain fewer residues
from chemicals employed in conventional agriculture. However,
the subject remains a matter of controversy.
estins (IARC group 2B, possible human carcinogens), and
also testosterone (IARC group 1, human carcinogens).
The toxicity of antimicrobial drugs is constantly reviewed
by international and national regulatory bodies. The Panel
notes the findings on hormonal anabolic agents and also the
lack of epidemiological evidence. Because there is no supporting
epidemiological or other evidence, the Panel made
no judgements.
4.9.1.3 Genetic modification
Plant breeding is a process of genetic exchange which is often
undertaken with the purpose of acquiring traits that are
either beneficial to humans or increase yield. More recently,
the use of new technologies of genetic modification, intrinsic
to agriculture and animal husbandry from their beginnings,
has raised great public interest and controversy. Many
crops are now genetically modified by means of gene transfer
within and between species. Potential uses of modern
genetic modification technology in food production include
changing nutritional composition (for example, betacarotene
in ‘golden rice’); increasing the hardiness of crops;
improving pest or disease resistance; and increasing herbicide
tolerance in crop plants (to allow the use of generic
herbicides).
Not all genetic modifications include transgenes, in which
a gene from one species is transferred across species, or even
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P ART 2 • EVIDENCE AND JUDGEMENTS
kingdoms — that is to say, from plants to animals. Some
genetic modifications involve only inactivating existing
genes. For example, tomatoes have been genetically modified
to render inactive the enzyme that softens the tomato
once ripe; thus, the tomato remains hard despite being ripe.
This is beneficial for transport and storage purposes.
The production and use of transgenic and genetically modified
foods for humans or animal consumption are regulated
in most but not all countries. The regulations require that
all genetically modified foods be of equivalent safety as
the food they are replacing, both nutritionally and
toxicologically.
Any effect of genetically modified foods on risk of human
disease might be a result of changes in the types of chemical
pesticides or herbicides used, rather than of genetic modification
itself. Genetically modified crops may require less
use of pesticides and herbicides.
Any effect of modern methods of genetic modification of
foods on the risk of cancer is unknown. Because there is no
supporting epidemiological or other evidence, the Panel
made no judgements.
There is too little evidence to draw any conclusion about
the association between methods of production and risk of
cancer.
4.9.2 Preservation
Methods of preserving foods have probably been in use since
before recorded history began. Gatherer–hunter and peasant–agricultural
food systems (see chapter 1.1) include
various techniques to preserve foods, which remain in use,
such as drying, underground storage, fermenting, smoking,
and salting. A range of other methods of preservation accompanies,
and is part of, industrialisation and urbanisation.
These include canning, bottling, refrigeration, heat treatment,
and irradiation.
Methods of food preservation, where epidemiological evidence
shows or suggests an effect on the risk of cancer, are
summarised and judged earlier in this chapter. These are
refrigeration (box 4.6.4); processing meat (‘processed meat’
refers to red meats preserved by smoking, curing, or salting,
or by the addition of chemicals, see box 4.3.1 in chapter 4.3);
preserving fish Cantonese-style (see box 4.3.5 in chapter
4.3); and salting (chapter 4.6).
4.9.2.1 Drying
Drying is an ancient method used to preserve cereals
(grains), pulses (legumes), fruits, and other plant foods. It
is also used to preserve meat and fish, often as part of another
preservation process such as salting (see box 4.3.5 in chapter
4.3). Freeze-drying, where the food is frozen and the
water extracted, has been in commercial use since the mid-
20th century, and is used to preserve fruits, herbs, meat, fish,
milk, eggs, coffee, and other foods.
4.9.2.2 Fermenting
Fermentation is an ancient method used to preserve many
foods and drinks. It may originally have been discovered by