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36. Who is responsible for ensuring GM crops do not cause harm to the environment?
The Office of the Gene Technology Regulator is responsible for overseeing genetically modified research and products in Australia.
Before any new GM crops are brought to market they are thoroughly evaluated for environmental and human health and safety impacts on a case-by-case basis by the Regulator, often over a period of eight years. Public comment is sought before GM plants are released into the environment.
The safety aspects of all GM crop trials are rigorously assessed by the Gene Technology Technical Advisory Committee (GTTAC) — an independent panel of scientific experts. Risk management plans are also devised to manage any possible risks to human health and the environment.
Ongoing assessment and evaluation of the crops is also part of the safety assessment process. A GM commodity will not be allowed to be released into the environment in Australia if it is deemed to pose unmanageable risks.
37. How much do we know about the environmental impact of GM crops on insects and other plant species?
Research in this area is continuing. Some GM crops have the potential to improve biodiversity by allowing more environmentally friendly farming practices. For example, GM insect-resistant cotton grown in Australia has allowed growers to halve their pesticide use. Fewer chemical applications mean less residues in the environment, and less harm to beneficial insects. Beneficial insects are those insects which ‘assist’ a crop (for example, by eating predators).
Concerns have been expressed about the development of GM crop monocultures. A monoculture is defined as the cultivation of a single crop on a farm or in a region, or a single culture without diversity. Problems associated with monoculture crops include the loss of agricultural biodiversity, and vulnerability to disease outbreaks. Agriculture, independent of GM crops, can already be described as a monoculture in some cases.
These issues are investigated before approval is given to commercialise a GM crop. The GM cotton varieties approved in Australia pose no greater risk to existing monoculture issues than the current conventional varieties.
CSIRO undertook a multi-million dollar research project to generate more information on the environmental impacts of GM crops. The project investigated how a broad range of GMOs might impact on the environment at the landscape or ecosystem level.
Part of the research project has involved insect resistant GM cotton. Scientists have found that the insecticide (Bt) toxin is produced in small amounts through both the leaves and the roots of the cotton. The majority of the toxin degrades within two to four weeks of being incorporated into the soil. The conclusion of the research is that, in general, Bt toxins from GM cotton will not have an adverse effect on the environment.
38. Are GM crops compatible with sustainable agriculture?
Genetically modified crops provide additional tools for farmers developing integrated pest and weed management systems, so they can add to ecologically sustainable development.
Genetically modified crops have the potential to:
- reduce chemical usage;
- allow more environmentally friendly herbicides to be used;
- reduce the level of tillage required; and therefore,
- reduce the potential of erosion, and loss of organic matter from the soil.
Insect resistant cotton, known as Bollgard® II, represents 85 per cent of Australia’s cotton crop and has reduced pesticide use by 85 per cent over conventional varieties. The experience with GM herbicide tolerant soybeans in the USA has seen an increase in the number of farmers practicing no-till farming. Also known as conservation tillage, this practice reduces soil cultivation and minimises the loss of topsoil. In the USA conservation tillage has led to reductions in soil erosion caused by wind and water by almost one billion tons per year. This is translated into benefits not only for the environment in relation to erosion, water quality, and wildlife, but also for farmers in relation to moisture available to plants, reductions in fuel use, and healthier soils.
39. Will insects become resistant to GM crops over time?
Insect pests could become resistant to insect-resistant GM crops such as Bt cotton, just as they do to insecticides. For this reason, where GM insect-resistant crops are grown there are strict management practices implemented. For example, with GM insect-resistant cotton, non-GM ‘refuge areas’ are established within the crops for insects to feed on.
Non-GM refuge areas encourage insects from within the GM crop to interbreed with insects from the refuge area, and this slows the development of resistance.
Bollgard® II cotton contains two genes from a soil bacterium, because of this the potential of the targeted pests developing resistance to the toxins produced is minimal.
40. What about the effects of GM corn on the Monarch butterfly?
The possible effects of GM plants on animals and the environment were raised in 1999 after a Cornell University study indicated that Monarch butterflies died after eating pollen from GM corn. The research based on laboratory studies showed that Bt corn pollen eaten in high concentrations killed Monarch caterpillars.
In an effort to confirm the laboratory findings, the United States Department of Agriculture commissioned comprehensive field studies at several major universities.
The field study results did not support the laboratory findings. In fact, they suggested that Monarch butterflies fared better at the edges of GM crops than they did in nearby woodlands.
A study published in the US National Academy of Sciences in June 2000 has also shown that black swallowtail butterflies, which also feed on plants growing in and around cornfields, are not harmed by the pollen from GM corn. The authors commented that “gene technology…may potentially contribute to preserving agroecosystem biodiversity relative to other pest management options."
The potential risks of harm to non-target organisms of GM crops is continually being investigated. Bt cotton grown in Australia has been shown to pose no harm to beneficial insects in cotton fields.
41. Can GM crops transfer modified genes to conventional crops?
Cross-fertilisation or gene transfer can occur between conventional crops and GM crops. Pollen, carrying the modified gene from a GM crop, could spread to a related, conventional crop by the wind or insects.
Factors which may limit cross-pollination of GM and non-GM crops include:
- Cross-fertilisation cannot occur between GM and conventional crops if they flower at different times.
- Under field trial conditions, GM crops may be required to be kept separate if they do flower at the same time, and buffer zones are often used for this purpose.
- Pollen from within the non-GM crop further reduces the risk of cross-pollination. If pollen from a GM crop drifts into a conventional crop that is also flowering, it must compete against the pollen from the conventional crop.
Studies have been undertaken worldwide on GM crops such as canola, corn, sugarbeet, cotton and potato to investigate the pollen movement from these crops. The results of these studies form the basis of regulatory management.
42. What is a buffer zone?
A buffer zone is an area of non-GM crops planted around GM crops to prevent pollen drifting into nearby fields and pollinating other crops and weeds. It acts as a trap for pollen carried from the GM plants by insects such as bees. If a bee has been collecting pollen from a GM crop, it is then more likely to visit the flowers on the buffer plants than to fly over to visit plants further away.
The width of buffer zones varies for each crop. For example, canola pollen can be spread by the wind and bees so the OGTR has required GM canola trials in Australia to have a 15 metre buffer zone or pollen trap of non-GM canola, surrounded by a 400 metre isolation zone which is free of canola or its relatives. If a buffer zone is not used, a one kilometre isolation zone is required by the Regulator. A monitoring zone of 50 metres immediately surrounding the buffer zone is also required within the 400 metre isolation zone. This zone must be kept free of any plants related to canola during the field trial period, and free of volunteer plants (not weeds or other plants) for three years after the trial. A volunteer plant is the offspring of the GM plants or the plants in the pollen trap.
The Regulator requires buffer plants to be destroyed after field trials to help contain pollen at the trial site.
43. Could GM plants escape farms and become weeds?
Results of a study investigating the possibility of GM plants escaping into natural habitats have been published in Nature magazine. The study involved planting four GM and non-GM crops (canola, potato, corn and sugar beet) alongside each other in 12 different habitats and monitoring them over a 10-year period. The GM crops were either herbicide tolerant or insect resistant.
The UK-based study was established to investigate the validity of concerns that GM crops would become weeds and invade natural habitats, or that the introduced genes would be transferred by pollen to wild relatives whose hybrid offspring would then become weedy or invasive.
The plants did not become weedy, invasive or self-sustaining. The GM plants fared the same as the non-GM plants – within four years all the corn, beet and canola plots had died out. Only one plot of potatoes lasted the full decade, and all of the survivors were non-GM.
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