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AgVetLink August 2003

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Purpose of withholding periods

Registrants are reminded that regulatory withholding periods (WHPs) are set by the ACVM Group purely to manage the risk of violative residues occurring in treated produce at the time of collection.

It is not a tool to manage any other concerns the registrant may hold for the product (e.g. product quality).

A critical consideration in setting the WHP for plant compounds is the time that harvesting of treated crops must occur. The same is not true for veterinary medicines where the WHP for milk, egg and meat harvested for human consumption can be set at any point after residues fall below the allowable limit.

Consideration of good veterinary practice (GVP), good agricultural practice (GAP) and the desirability for the least WHP possible has meant that the periods requested by registrants for veterinary medicines are at or close to the time at which edible products are first eligible for human consumption.

Some registrants have elected WHPs significantly longer than necessary to manage the risk of residues. This has been accepted as being the registrant’s prerogative in the past. However, the ACVM Act requires that conditions placed on product registrations (such as the withholding period) be sufficient to manage risks but also impose least cost to the public. In consequence, where a conservative WHP has been requested despite the availability of data supporting a reduced time and the approval of the prolonged WHP is considered likely to impose a cost on the public, the ACVM Group may not approve it.

Registrants with data that support a shorter WHP are encouraged to apply for a reduction in the approved WHP, particularly if the current WHP is significantly longer than is necessary and where the additional time may lead to restrictions in GVP or GAP.

 

Default withholding periods for veterinary medicines

Registrants are reminded that the default withholding periods applied to provisional registrations are now a recognised option for products fully registered under the ACVM Act. Although the preferred withholding periods remain those approved following assessment of a residue package, the ACVM Group recognises that it is not economically viable for registrants to produce a residue package for all potential food uses of a veterinary medicine, and that default withholding periods are useful in such circumstances.

Default withholding periods are necessarily conservative and have been agreed upon by the Animal Products and Dairy Groups of the NZFSA. Some historical registrations were approved with withholding periods that were not approved following assessment of residue data. Such periods are variable; however, most were set at 28 days.

Any historical products with a withholding period that was not approved as the result of data assessment or consideration of technical argument will be expected to change to the current default withholding period (e.g. 63 days horse meat). This change will be enforced when products are updated or an application is made to alter an already updated label.

Should registrants wish to supply data and/or technical argument to reduce the ‘default’ withholding period, they may be provided at the time of update. A separate application will not be required; however, the ACVM Group will charge the standard hourly rate ($108.00 plus GST) for the time taken to complete the assessment.

The current default withholding periods are included as Appendix A in ACVM Registration Information Requirements for Provisional Registration. They will be included in the veterinary medicine residue standard at the next update.

 

Australian workshops

Two workshops (to be hosted by Avcare and VMDA) will be held in Sydney and in Melbourne in late August/early September. They will be based on the programmes run in New Zealand in November last year, but will be updated with recent infor-mation.

There will be ‘breakout sessions’ for veterinary medi-cines and plant compounds in the afternoon. Keep a watch on the website if you are interested in attending.