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Pesticide Residues - Global Zoning Iniative

At a recent meeting the OECD Pesticides Forum set up an expert Steering Group to develop a global zoning scheme in order to define areas in the world where pesticide residue behaviour could be considered comparable. Therefore residue trials data from anywhere in each zone could be used for MRL-setting purposes in any country within that zone.

The initial proposal for this zoning scheme arose out of an earlier EU/ OECD workshop (York, 1999) where it was realised that the national practices in accepting data from other areas or countries differed significantly between Europe (2 zones) and North America (13 zones), and that there was room for harmonisation efforts in the area.

Dave Lunn, having been involved in the initial workshop in York, was invited to join the Steering Group, and his attendance at the first meeting of the group was supported jointly by the NZ Vegetable & Potato Growers Federation and the ACVM Group.

The Steering Group confirmed that it was technically feasible to define geographic zones for the purposes of extrapolating residue behaviour and confirmed that, once validated, the acceptance of this zoning scheme would:

• promote the mutual acceptance of residue trial data between countries, thus reducing the total number of global trials likely to be needed to support an MRL;

• reduce the need for multiple residue trials at the national level to support MRLs for minor crops;

• facilitate the acceptance of Codex MRLs by providing greater confidence in the validity of the supporting residue trials.

After taking into account the views of the OECD Working Group on Pesticides (that any such zoning scheme should be simple and practical), and recognising the resource implications associated with the development of a complex scheme that would cover all possible pesticides and their methods of use, the Group agreed:

• to focus on a zoning scheme that was appropriate for pesticides applied as foliar sprays and to construct a tentative map of 5-7 ‘residue zones’, based on Koppen’s climate classification (this task was allocated to Don Griffin, UK PSD);

• to collect as much residue data as possible from recent JMPR evaluations and compile this in such a way that it could be used to validate the tentative zones or adjust their boundaries (it was agreed this work would be shared between Dave Lunn and Dugald MacLachlan from the Australian NRA);

• to convene a further meeting of the Group in April 2001 (to coincide with the next meeting of the Codex Committee on Pesticide Residues), where the tentative zones and the collated residue data would be considered and the validation process confirmed.

It is expected that this work, once completed, will have the effect of reducing the number of New Zealand residue trials required. It will mean that New Zealand trials will be applicable for use in other countries (within zones) and vice versa. The ACVM standard will be revised as soon as the work is completed.