Government changing regulation of inhibitors

An amendment is being made to the ACVM Act to define all products with an inhibitor claim as an agricultural compound.

Under these new rules, to register a product for commercial sale, a manufacturer needs to provide information and research in New Zealand conditions, covering:
•            the composition of the formulation
•            residues relating to use on food-producing crops or animals
•            animal and plant safety
•            efficacy of the product.

MPI will assess the risks related to food safety, trade, animal welfare, and truth in labelling. Registration is granted if all the requirements are met.

A year-long transition period will apply from when the bill is live. In the meantime, an interim measure is in place.

For inhibitors not included in the interim measure (in place until March 2024) applications can still be made.

MPI encourages those working on inhibitors to discuss options with ACVM (Warren Hughes) before making an application.

Other regulators (EPA, Food Safety, GHG, CODEX) may also be considered (depending on the compounds used and if approval is required to sell on overseas markets).

MPI encourages manufacturers to apply for registration as soon as they are ready. If a product is not registered by 18 July 2024, or one year after the amendment to the ACVM Act comes into force, whichever comes first, it cannot be imported, manufactured, sold, or used until it is registered. Manufacturers with questions can get case-by-case advice by emailing

MPI Brochure: Your guide to the new rules for inhibitors

Process for inhibitor applicants

Codex approval is required to sell inhibitor products overseas if residues apply. The default MRL is 1 ppm for authrorised or unauthorised compounds. It is also used where there is no label and is a ‘catch all’ for off-label use.

An inhibitor used on plants is considered by a pesticides committee.

For animals, an animal remedies committee will consider the implications of consuming pasture with inhibitors applied or if they are administered directly.

Efficacy Data

  • Discuss details needed with ACVM.
  • Core data for GHG inventory do not require residues, but ACVM does.

GHG Inventory reviews the research to test, for example:

  • demonstrated statistical significance for international scrutiny
  • longevity of response when treatments are withheld
  • trade-off or co-benefits on other GHG may need to be quantified

GHG Inventory is drafting guidance for this part of the process.

Contact for guidance

Making an application

Data Assessment

To prepare a registration application for the ACVM, independent data assessors are required to assess chemistry and manufacturing, efficacy, crop safety, target animal safety and residue data before submission.

Data assessment reports must be in the appropriate ACVM template.

ACVM will advise on whether:

  • the data sets are relevant;
  • the information provided complies with ACVM guidance documents;
  • the conclusions made are appropriate;
  • there are any deficiencies or gaps in the information provided.

The applicant is responsible for addressing any deficiencies by providing additional information:

  • to the data assessor who will update the report(s), or
  • (if minor) addresses deficiencies.

Check that the data assessor has the appropriate expertise and declare and manage any potential and perceived conflicts of interest.

The assessor should be:

  • independent from trial data generation and reward (financially or otherwise), relating to the product.
  • able to demonstrate expertise in the field.

Animal and Plant Health NZ member data assessors

NameCompany namePhoneLocationE-mailScope
Richard KeeneKeene Manufacturing Solutions Ltd021 meds
Dr Julia McNabIntuit Regulatory & Marketing Ltd.027 meds
Lidija PetreskaOn Regulatory Ltd.09 479 8864Aucklandlp@onregulatory.comAgrichemicals, Vet meds, VTAs


Full list of assessors

If you cannot source a suitable data assessor, ACVM can provide this service. The team is also seeking more data assessors, if you know someone who is suitable. Contact

ACVM considers a data assessor's suitability relating to the data package, including confidence in maintaining objectivity in the quality of the data and registration process.

A declaration of conflict of interest is required for every data assessment report, including how risks are being managed:

  • Have you been involved in trials or research and development sponsored by the registrant or applicant?
  • Have you been involved in trials or other research and development in relation to the product being assessed?
  • Do you hold a financial or personal interest in the registrant’s or applicant’s company, or have any other personal or financial involvement with the registrant or applicant?
  • Are you involved in trials or other research and development work with another registrant or applicant who has a product that is in direct competition with the product that will be assessed?
  • Are you aware of a conflict of interest, including the data being assessed and any other review or research work, which could adversely impact on an objective review of the material?

ACVM will consider real and perceived conflicts.

ACVM may accept data assessment reports if potential or perceived conflicts of interest can be satisfactorily managed. If concerns arise, an independent expert opinion may be requested to manage any conflict of interest.

Contact ACVM if you are unsure about the potential for a conflict of interest.

Funding initiative for inhibitors

A government and industry venture - Centre for Climate Action Joint Venture Ltdwhich kicked off in February 2023, provides funding to assist initiatives that reduce the impacts of climate change, including inhibitors. The investment organisation encourages anyone to discuss options with them before investing in inhibitors.