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  • In 2002 and 2003, research conducted by Lincoln University's Agribusiness and Economics Research Unit (AERU) with focus groups found out what New Zealanders think about using a genetically modified bacterium to break down toxic DDT residues in the soil.

    DDT is a pesticide that was used on New Zealand farms in the 1950s and 1960s to kill insects, particularly grass grub. DDT residues stay in the soil for many years – they are still in our soil 50 years on. What do New Zealanders think about the use of bioremediation to help clean up DDT in our soils?

    The DDT problem

    DDT was initially used to control grass grub. Grass grubs are a native insect that eat the roots of many grasses, especially ryegrass. Ryegrass is one of the most common grasses on farms. Read more about DDT and other organochlorines.

    In 1970, DDT was banned from use on farmland, but unfortunately DDT residues stay in the soil for many years. When animals accidentally eat DDT-contaminated soil while eating grass or feed crops, the DDT residues build up in their fat tissue. This causes the contamination of the animal's meat and milk. Fonterra will not collect milk if the DDT residues are 1 mg/kg milk fat or more. Land with high levels of DDT residues is therefore not good as farmland.

    A possible solution

    A genetically modified bacterium has been created that breaks down DDT residues in the soil. This would help remove the DDT residues from New Zealand soil, decreasing the risk they pose to our exports of milk and meat.

    What do New Zealanders think?

    The research found that public opinion is divided over whether this application of biotechnology is acceptable or unacceptable. There were a total of 117 people surveyed in these focus groups.

    People were concerned that putting these bacteria in the ground would be an irreversible step. As one person commented, "There is no way you can say, 'That doesn't work, take it out of the ground'." This would be especially problematic if there were unforeseen circumstances, such as the genetically modified bacteria "gobbling up" other beneficial bacteria in the soil or becoming pathogenic to humans, other mammals or organisms living in the soil.

    Soil was recognised as one of New Zealand's most important resources, for a variety of reasons. People were supportive of taking measures to look after it. Cleaning up DDT residues was seen to have economic benefits for New Zealand. Opinion was divided about whether using the genetically modified bacteria is the best way to do it.

    Survey respondents felt the need to right a wrong, but this was balanced by a concern not to create another problem.

    Useful link

    The AERU report, Public Understandings of Biotechnology in New Zealand: Factors Affecting Acceptability Rankings of five Selected Biotechnologies (#266) can be downloaded from the AERU publications list on the Lincoln University website, here.

      Published 16 November 2007 Referencing Hub articles
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