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OECD pesticide residue zoning scheme

Over the last two years, a small group of residue experts from OECD countries have been developing a global zoning scheme to define areas in the world where pesticide residue behaviour could be considered comparable, and therefore where residue trials data could be used within each zone for MRL-setting purposes, irrespective of national boundaries.

Dave Lunn, who was involved in the initial residue harmonisation workshop in York (1999) where this zoning scheme was first proposed, was invited to join this Steering Group. His participation is supported by MAF Food’s ACVM Group and by the NZ Vegetable & Produce Growers and the NZ FruitGrowers Federations.

At the first meeting, the Steering Group confirmed that it should be possible to define geographical zones for the purposes of extrapolating residue behaviour but that further work would be needed to validate this concept and to define the appropriate zones.

The second meeting of the Steering Group, held in Paris (29-30 March 2001), refined the JMPR residue data sets intended for use in validating the proposed zones and supported the use of a statistician to analyse the data to estimate residue variability within and between the proposed four zones.

Initial indications from the statistical analysis suggested that the proposed zones, based on average climate, were not appropriate because they were too general. After consulting with several of the European members of the Working Group, it was agreed to assess the variability associated with estimated climatic conditions close to harvest for each residue data set. This approach was suggested to investigate the option of proposing various temperature, rainfall and sunshine ‘bands’ within which residue trials could be considered equivalent.

Recognising that this was a significant departure from the initial concept, and because the statistical analysis had identified a number of anomalies, a special review meeting of the Zoning Steering Group was arranged in Geneva on 28 September 2001. After spending considerable time discussing the statistical analysis and attempting to explain the anomalies, the meeting concluded that the available data was not sufficient to separate out the various factors that could contribute to residue variability, although there was a strong indication that climate may not have such a major influence.

The meeting agreed to collect additional information (residues at ‘day 0’) for the residue data sets available, and to test the hypothesis that compared to other factors, climate has little influence on residue variability (thus supporting the suggestion that residue data based on the same good agricultural practice should be globally ‘transportable’).

It was agreed that this ‘refined’ analysis would be considered at the next meeting of the Working Group (April 2002) where, hopefully, a series of recommendations could be developed for consideration by OECD and FAO.

Comments on amendments to the ACVM Regulations

In the October issue of AgVetLink the ACVM Group proposed some amendments to the ACVM Regulations 2001 to:

• include some additional groups for exemption from registration;
• amend some definitions; and
• add substances to the GRAS lists in Schedule 7 parts A and B.

Only two written submissions were received. The first concerned the proposed exemption from registration of unregistered trade name products used by veterinarians. The respondent pointed out that further limitations must be imposed to ensure that unregistered products are used by veterinarians only when there is no equivalent product registered in New Zealand and only prescribed in individual cases in which it is essential for the immediate welfare of the animal. The ACVM Group supports this view and will modify the exemption accordingly.

The second submission concerned the definition of raw and composted biological wastes. The respondent was concerned about the implications of defining biological wastes and considered it necessary for interested and affected parties to discuss the definition before it is incorporated into the Regulations. The ACVM Group accepts this view and will not recommend any definition until the  interested and  affected parties can be consulted.

Apart from the concern over the definition of raw and composted biological wastes, the amendment of the Regulations must be progressed. The ACVM Group will prepare policy papers for Cabinet to consider before the end of the year. The new Regulations are not likely to commence before April 2002.