The Political Economy of Regulation of Biotechnology in Agriculture - The Oxford Topic of Food, Politics, and Society - page 694

Growing phase

Seedbed
preparation;
Start material

Storage;
Processing;
Transport

Sowing Growing Harvest Post-harvest Supply chain

(a) Potential avenues for on-farm mixing between genetically modied (GM) and non-GM crops

Volunteers from
GM pre-cultures;
dispersal of GM
seeds via straw
and/or manure

Seeds;
Mixing in
machinery
during sowing

Cross-
fertilization;
dispersal of GM
seeds via straw
and/or manure

Mixing in
machinery
during harvest

Volunteers Mixing during

on-farm storage
and processing;
Mixing during
transport to
collection point

(b) On-farm co-existence measures to ensure the purity of a crop

Control of
volunteers;
Specic tillage
operations;
Application of
herbicides
and/or
weeding

Cleaning of
storage and
processing
rooms;
Cleaning of
transport
vehicles

Seed purity Spatial isolation

(isolation
distances); Field
characteristics;
Pollen barriers;
Temporal
isolation (period
of owering,
rotation)

Cleaning of
machinary;
Removal of
bolters

Cleaning of
machinery;
Manoeuvre
space for
machinery

Figure 28.1 Potential avenues for on-farm adventitious mixing between genetically modi-
fied (GM) and non-GM seeds (a), and proposed on-farm co-existence measures aimed at
ensuring the purity of a crop during the production process (b) (Devos et al. 2009).

on of transgenes to viable offspring through cross-pollination. GM seeds cannot be dis-
tinguished readily from non-GM seeds visually; molecular tests are needed to detect
them. It is therefore not possible for producers to confirm the presence of GM crops
on their land or monitor/manage their spread, except through costly genetic testing.
Several issues arise from the reproductive properties of GM crops that present new
risks to organic producers not encountered with the use of synthetic agrichemicals. For
example, non-GM farmers are vulnerable to inadvertently committing a “patent viola-
tion” by having rogue transgenic offspring appearing in their fields. This can happen if
non-GM plants are cross-pollinated with their GM counterparts and the resulting seed
is saved and planted in the following year. This can also happen if seeds produced from a
GM crop fall to the ground and are left to germinate and grow as volunteers in field plots
planted with non-GM seed in the following seasons. Seeds produced by these volunteer
GM plants could then become commingled with non-GM seed during harvest, which
may result in a positive test for the presence of the GM seed in an ostensibly GM-free
seed shipment. A positive test for the presence of GM seed directly affects the ability of
organic (or non-GM) farmers to obtain a premium price for their seeds.
Fukuda-Parr (2007) suggested that three major areas of risk underlie the global
debate over the use of transgenic crops in agriculture: (1) ecological and human health
risks, (2) socio-economic risks and, (3) cultural risks of foreclosing consumer and public
choice. A substantial literature covering the ecological and human health risks strongly
supports the safety of the transgenic crops currently approved for commercial use (e.g.,
Thies and Devare 2007), with a few, highly publicized exceptions, such as Séralini et al.
(2012), a study whose validity is strongly disputed in mainstream science, and one in
which the findings were eventually retracted by the journal that had published it ( http://